• Popular Science: What is the difference between different extraction methods of CBD oil? _ CBD oil _ hemp.
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    Original title: Popular Science: What is the difference between different extraction methods of CBD oil? _cbdoil The potential health benefits of CBD (also known as DM CBD in China) for humans and even animals are a prominent topic of current research and discussion. It is important to understand the different types of extracts as we interpret the effects of CBD. Cannabidiol (CBD) is extracted from the cannabis plant in various forms. The different extraction methods used in different products directly determine the different effects and effects of CBD on the body. Before purchasing or using, we suggest that every consumer must understand the differences between them. Full Spectrum CBD, Broad Spectrum CBD, Isolate CBD and PCR CBD are four common forms of CBD extracts. They contain cannabinoids and types of synergistic plant extracts. To help you find and choose the right product for your needs, we compared and studied the four types of products, learned the differences between them, and learned how these differences affect CBD intake. Full spectrum Full-spectrum or whole-plant cannabis extracts maintain the integrity of the cannabis plant. In addition to CBD, this extract includes terpenes, cannabinoids, vitamins, minerals, fatty acids,winterization filtration, phytonutrients and any other substances derived from the cannabis plant. Cannabis plants naturally contain more than 100 cannabinoids, similar to CBD, which provide unique benefits. Full spectrum extracts contain all the available benefits in cannabinoids. The whole plant cannabis extract benefits from the synergistic properties between the individual cannabinoids by maintaining all plant components. Scientists have discovered that plant components interact to produce an enhanced effect (compared to the components alone). Expand the full text According to the theory known as the entourage effect, CBD and other components of marijuana work together to improve absorption and effectiveness in the body. These compounds affect each other's function,wiped film distillation, and the sum is greater than its parts. Whole plant cannabis extracts contain a small amount of THC due to the integrity of the natural cannabinoids. However, according to regulations for industrial hemp, whole plant cannabis extracts must have a THC of less than 0.3%. This is a hallucinogenic dose. Broad spectrum CBD Broad-spectrum CBDs are basically full-spectrum CBDs that contain a range of cannabinoids and terpenes, but not tetrahydrocannabinol (THC). This is a great option if you want to maximize the benefits of CBD, but without the risk of failing a drug test. Broad-spectrum CBD is manufactured by passing the product through an additional process to isolate and eliminate THC while still retaining other natural cannabinoids and terpenes. Because multiple cannabinoids and other compounds are protected in a broad spectrum of CBD, it can provide the enhanced benefits of the Accompanying Effect without the psychoactive effects of THC. An example of this is cannabis oil tincture, which is full spectrum but THC-free. Let's explain the manufacturing process of this product. Hemp oil tincture starts as a full spectrum oil. There are various methods of extracting full-spectrum cannabis oil from the cannabis plant. While CO2 extraction is considered the cleanest method, other methods, such as solvent extraction, hemp extraction centrifuge ,jacketed glass reactor, can be used. Regardless of the extraction, the final product will be an oil with varying amounts of THC not greater than 0.3%. At this point, most manufacturers will use the oil in combination with several other ingredients or as is. Using a technique called centrifugal partition chromatography (CPC), manufacturers of cannabis oil tinctures take an additional step. CPC is a tool for purifying cannabis extracts. The CPC technique separates each compound to remove unwanted compounds such as THC. During CPC, the crude oil is run through a centrifuge. Push the oil through a series of cells containing a mixture of liquids, such as water, methanol or heptane. Each compound diffuses into a fluid based on its affinity for each other; the compounds separate into different cells along the way 。
    The compact CPC unit uses more than one thousand extraction cells in a high-speed rotating disk stack to separate and purify the desired compounds. Each cell increases the purity of the desired compound until a highly pure product is produced. Additional CBD isolates are then added to the final product to increase potency. Separated CBD CBD isolate is cannabidiol in its purest form. To produce this extract, the CBD is isolated and then refined to remove any other cannabinoids, terpenes and plant components found in the cannabis plant. The final product is a fine white powder that is about 99% cannabidiol. Isolates contain only one cannabinoid: CBD. This means that CBD Isolate does not contain any THC, a psychoactive cannabinoid that has hallucinogenic properties, making CBD Isolate a perfect choice for people seeking THC-free products. The isolate has no taste or odor and can be used to formulate a variety of CBD products, such as foods and topical supplies. Because the purity of the CBD isolate is about 99%, you can precisely control the amount of product added (one milligram of CBD isolate is equivalent to about one milligram of CBD). When it comes to products such as vape juice or tinctures, it is easy to identify them as CBD isolators if the color is very clear. Although other ingredient can be added to darken that liquid. PCR - Phytocannabinoid Rich CBD Phytocannabinoid-rich cannabis oil or PCR is a term most commonly used to describe cannabis oil that contains a variety of different cannabinoids and 0THC. In other words, PCR is a common alternative term for broad-spectrum cannabis oil. However, it is important to note that PCR is generally used for profiling and can also refer to full spectrum products, which contain up to 0.3% THC. If CPC technology is available, you may wonder why all products are not THC. THC, an intoxicating compound of the cannabis plant, is a concern for people who don't want to experience marijuana intoxication or have to take part in routine drug testing. While beneficial for these reasons, THC is also being studied for its interaction with CBD, which we refer to as the companion effect. Description of broad-spectrum CBD or full-spectrum products without THC Please note that not all products with the Full Spectrum or No THC label will be produced in this manner. We advise you to be wary of products that claim to be full spectrum and THC-free. Many times, THC-free "full spectrum" products contain only CBD isolates. If in doubt, refer to the manufacturer's COA (Certificate of Testing) to determine the amount of cannabinoids in the product. Conclusion With CBD separation products, you get the only benefit of cannabidiol (CBD). In contrast, full-spectrum or whole-plant cannabis extracts provide the synergistic benefits of the entire cannabis plant, while PCR and broad-spectrum CBD allow you to enjoy the health benefits of cannabinoids without the psychoactive effects of THC. Whether you choose a CBD isolate, PCR,cbd centrifugal extractor, full spectrum or broad spectrum depends on your health goals. In some cases, all of these have proven to have different benefits. As the scientific community learns more about CBD, we are beginning to understand how CBD interacts with the body as well as other plant components. Do you have any other questions about the use of whole plant cannabis extract and CBD isolates (known domestically as DM CBD)? Return to Sohu to see more Responsible Editor:. toptiontech.com

  • Evaporator Classification Design Selection Information All you want is here _ Cycle
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    Original Title: Evaporator Classification Design Selection Information All You Want Is Here 1 Type of evaporator With the continuous development of industrial evaporation technology, the structure and type of evaporation equipment are constantly improved and innovated, with a wide range of different structures. At present, there are more than 60 kinds of evaporation equipment in industry, of which more than 10 types are most commonly used. This section only introduces a few commonly used types. The common evaporator is mainly composed of a heating chamber and a separation chamber. There are many types of heating chambers. At first, jacketed or coiled heating devices are used, followed by horizontal and vertical short-tube heating chambers. Then the vertical long tube liquid film evaporator and the scraper film evaporator were invented. According to the flow of solution in the evaporator, the indirect heating evaporator commonly used in industry can be roughly divided into two types: circulation type and one-way type. 1. Circulation type evaporator The characteristic of this kind of evaporator is that the solution circulates in the evaporator. According to the principle of liquid circulation, it can be divided into two types: natural circulation and forced circulation. The former is the natural circulation caused by the density difference of the solution due to the different heating degree of the solution at different positions of the heating chamber, while the latter is the forced circulation of the solution by external power. At present, the commonly used circulating evaporators are as follows: (1) Central circulation tubular evaporator Expand the full text The structure of the central circulation tube evaporator is shown in the picture. Its heating chamber is composed of a vertical heating tube bundle (boiling tube bundle). In the center of the tube bundle, there is a tube with a larger diameter, called the central circulation tube, whose cross-sectional area is generally 40 ~ 100% of the total cross-sectional area of the heating tube bundle. The central circulation tube evaporator has the advantages of compact structure, convenient manufacture and reliable operation, so it is widely used in industry and is called "standard evaporator". But in fact, due to the limitation of structure, its circulation speed is relatively low (generally below 0.5m/s); and because the solution circulates continuously in the heating tube, its concentration is always close to the concentration of the finished solution, so the boiling point of the solution is high and the effective temperature difference is reduced. In addition, the cleaning and maintenance of the equipment is not convenient enough. (2) Basket evaporator Since the boiling liquid is in contact with the evaporator shell at a lower temperature, there is less heat loss. The basket-type evaporator is suitable for evaporating the solution which is easy to scale or has crystal precipitation. Its disadvantage is that the structure is complex and the amount of equipment materials required for unit heat transfer surface is large. (3) Externally heated evaporator The characteristic of the external heating evaporator is that the heating chamber is separated from the separation chamber, which not only facilitates cleaning and replacement, but also reduces the total height of the evaporator. Because the heating tube is long (the ratio of the tube length to the tube diameter is 50-100) and the solution in the circulating tube is not heated, the circulating speed of the solution is high, which can reach 1.5m/s. (4) Levin evaporator The advantages of Levin evaporator are high circulation speed and good heat transfer effect. Because the solution does not boil in the heating tube, it can avoid the precipitation of crystals in the heating tube, so it is suitable for the treatment of solutions with crystal precipitation or easy scaling. Its disadvantage is that the equipment is huge and the required plant is high. In addition, since the static pressure of the liquid layer is large, the pressure of the heating steam is required to be high. (5) Forced circulation evaporator This kind of evaporator has the advantages of large heat transfer coefficient and good adaptability to materials with high viscosity or easy crystallization and scaling, but its power consumption is large. 2. One-pass type evaporator The characteristic of this kind of evaporator is that the solution flows along the wall of the heating tube in the form of a film and reaches the required concentration once through the heating chamber, while the residence time is only a few seconds or more than ten seconds. The main advantages of the single-pass evaporator are high heat transfer efficiency, fast evaporation speed and short residence time of the solution in the evaporator, so it is especially suitable for the evaporation of heat-sensitive materials. According to the flow direction of materials in the evaporator and the reasons for film formation, it can be divided into the following types: Rising film evaporator; Falling film evaporator; Rising-falling film evaporator; Scraper film evaporator. (1) Rising film evaporator The heating chamber of the rising film evaporator is composed of one or several vertical long tubes. The diameter of the heating tube is usually 25 ~ 50mm, and the ratio of the tube length to the tube diameter is 100 ~ 150.
    The climbing film evaporator is suitable for the solution with large evaporation capacity (i.e. dilute solution), heat sensitivity and easy foaming, but not suitable for the solution with high viscosity, crystal precipitation or easy scaling. (2) Falling film evaporator The falling film evaporator can evaporate the solution with higher concentration, and is also suitable for the material with higher viscosity. However, it is not suitable for the solution which is easy to crystallize or scale. In addition, because the liquid film is not easy to distribute evenly in the tube, its heat transfer coefficient is smaller than that of the climbing film evaporator. (3) Rising-falling film evaporator The rising film and falling film evaporators are installed in a casing to form a rising-falling film evaporator. After being preheated,molecular distillation systems, the raw material liquid is first raised by the rising film heating chamber, then lowered by the falling film heater, and finally separated from the secondary steam in the separation chamber to obtain the finished liquid. This kind of evaporator is mostly used in the situation where the viscosity of the solution changes greatly in the process of evaporation, the evaporation of water is not large and the height of the workshop is limited. (4) Scraper film evaporator In some cases, the solution may be evaporated to dryness to obtain a solid product directly from the bottom. The disadvantages of this kind of evaporator are complex structure, large power consumption, small heat transfer area, generally 3 ~ 4 m2, the maximum is not more than 20 m2, so its processing capacity is small. 3. Direct contact heat transfer evaporator In actual production, in addition to the above two types of circulating and single-pass evaporators with dividing wall heat transfer, direct contact heat transfer evaporators are sometimes used. Fuel (usually coal gas or heavy oil) is mixed with air and the resulting high-temperature flue gas is directly sprayed into the evaporated solution. The high-temperature flue gas is in direct contact with the solution, making the solution boil and vaporize rapidly. The evaporated water is directly discharged from the top of the evaporator together with the flue gas. Generally, the depth of the combustion chamber of this evaporator in the solution is 200 ~ 600mm, and the temperature of the high temperature flue gas in the combustion chamber can reach more than 1000 ℃. However,thin film distillation, due to the fast heat transfer rate when the gas and liquid are in direct contact, the temperature of the gas leaving the liquid level is only 2 ~ 4 ℃ higher than that of the solution. The nozzle of the combustion chamber is easy to be damaged due to its use at high temperature, so it should be made of high temperature and corrosion resistant materials, and its structure should be considered to be easy to replace. The submerged combustion evaporator is characterized by simple structure and high heat transfer efficiency. The evaporator is especially suitable for the evaporation of materials which are easy to crystallize, scale or corrode. At present, this kind of evaporator has been widely used in the treatment of waste acid and the evaporation of ammonium sulfate solution. However, it is not suitable for the treatment of materials that cannot be contaminated by flue gas, and its secondary steam is also difficult to use. Due to the limitation of space, the working principle of various evaporators is not introduced in detail in this article. If you want to know this content, you can search for evaporation crystallization in the chemical 707 app to see more details. There are so many evaporators, so how to design and calculate the evaporation process? Let's learn together! 2 Evaporator design steps 1. The calculation of multi-effect evaporation generally adopts iterative calculation method. (1) According to the process requirements and the nature of the solution, determine the operating conditions of evaporation (such as heating steam pressure and condenser pressure), the type of evaporator (rising film evaporator, falling film evaporator, forced circulation evaporator, wiped film evaporator), process and number of effects. (2) According to the production experience data, preliminarily estimate the evaporation capacity of each effect and the composition of the finished liquid of each effect. (3) Based on experience, assume that the pressure drop of steam passing through each effect is equal, and estimate the boiling point of solution in each effect and the effective total temperature difference. And (4) calculating the evaporation capacity and the heat transfer capacity of each effect according to the enthalpy balance of the evaporator. And (5) calculating the heat transfer area of each effect according to the heat transfer rate equation. If the obtained effective heat transfer areas are not equal, the effective temperature difference shall be redistributed as described below, and steps (3) to (5) shall be repeated until the obtained effective heat transfer areas are equal (or meet the accuracy requirements given in advance). 2. Calculation method of evaporator The calculation method of multi-effect evaporation is introduced by taking the evaporation device with three-effect cocurrent feeding as an example. (1) Estimate the evaporation capacity of each effect and the composition of finished liquid In the process of evaporation, the total evaporation is the sum of the evaporation of each effect. The feed liquid in any one effect is composed of In general, the evaporation capacity of each effect can be estimated according to the average value of that sent by the General Political Department, namely For the multi-effect evaporation of cocurrent operation, due to the self-evaporation phenomenon, it can be estimated according to the following proportion.
    For example, In the above categories: W — total evaporation capacity, kg/H; W 1 ,W 2 ,… , wiped film evaporator ,rotovap distillation, W n — evaporation capacity of each effect, kg/H; F — Flow of raw material solution, kg/H; x 0 , x 1 ,… , X n — composition and mass fraction of raw material solution and finished solution of each effect. (2) estimate that difference between the boiling point and the effective total temperature of each effect solution In order to obtain the boiling point temperature of each effect, it is necessary to assume the pressure. Generally, the heating steam pressure and the pressure in the condenser (or the final effect pressure) are given, and the pressure of other effects can be determined according to the assumption that the steam pressure drop between effects is equal. That is Where: -difference between heating steam pressure and secondary steam pressure of each effect, Pa; P 1 — pressure of the first effect heating steam, Pa; P 'K — pressure of secondary steam in the last effect condenser, Pa. The total temperature difference of effective heat transfer in multi-effect evaporation can be calculated by the following formula: Where: -total effective temperature difference, which is the sum of effective temperature difference of each effect, ℃; T 1 — temperature of the first effect heating steam, ℃; T 'K — the saturation temperature of the secondary steam at the operating pressure of the condenser, ℃; — Total temperature difference loss, which is the sum of temperature difference loss of each effect, ℃. In the formula — loss of temperature difference due to drop in vapor pressure of the solution, ℃; — loss of temperature difference due to the static pressure of the solution in the evaporator, ° C; — Temperature difference loss caused by pressure drop due to pipeline fluid resistance, ℃. The solutions of, and are respectively introduced as follows: a. The temperature difference loss caused by the decrease of the vapor pressure of the solution can be corrected by the correction factor method and the Duhring method. The rule is obtained. In the formula — temperature difference loss caused by solution vapor pressure drop under normal pressure, ℃; The boiling point, t a, of some solutions at atmospheric pressure can be obtained from the manual; — Correction factor, dimension one. Where: T '1 — Boiling point of water at operating pressure, i.e. saturation temperature of secondary steam, ℃; R '— vaporization heat of secondary steam under operating pressure, kJ/kg. Turing's rule: The boiling point of a solution is linearly related to the boiling point of a standard liquid (usually water) at the same pressure. A set of straight lines, called Turing lines, can be obtained on a rectangular coordinate graph with the boiling point of water as the abscissa, the boiling point of the solution as the ordinate, and the composition of the solution as the parameter. According to the composition of the solution and the boiling point of water at the same pressure, the boiling point of the solution at the same pressure can be found out by using the Duhring diagram, and then the value can be obtained. An approximation of the boiling point of a liquid at various pressures can also be calculated from Turing's rule. This method is based on the fact that the ratio of the difference between the two boiling points of a liquid at two different pressures to the difference between the two boiling points of water at the same pressure is a constant, namely Obtaining the value of K, the t 'A of the boiling point at any other pressure can be obtained from the following equation: (1-11) Therefore, the value of the solution can be calculated without using the Duhring diagram. b. Loss of temperature difference due to the static pressure of the solution in the evaporator Some evaporators are in the operating room, and the solution in the evaporator needs to maintain a certain liquid level, so the pressure inside the solution in the evaporator is greater than the pressure at the liquid level, resulting in a higher boiling point inside the solution than at the liquid level. The difference between the two is the temperature difference loss caused by the static pressure of the solution. For the sake of simplicity, the boiling point inside the solution can be found by the average pressure of the liquid surface and the bottom layer. The average pressure is approximately estimated according to the static equation: (1-12) Where: P m — average pressure between the liquid level and the bottom in the evaporator, Pa; P '— pressure of secondary steam, i.e. pressure at liquid surface, Pa; ρ — average density of solution, kg/m3; L — height of liquid layer, m; G — acceleration of gravity, m/S2. (1-13) Where: TPM — the boiling point of water calculated according to the average pressure, ℃; TP — boiling point of water calculated according to the secondary vapor pressure, ℃.
    Temperature difference loss caused by pressure drop due to pipeline flow resistance In multi-effect evaporation, when the secondary steam of each effect before the last effect flows to the heating chamber of the second effect, the pressure decreases due to pipeline resistance, and the saturation temperature of the steam also decreases accordingly. The resulting temperature difference loss is. According to the experience, the temperature difference loss caused by the pipeline resistance between each effect is taken as 1 ℃. According to the estimated secondary steam pressure of each effect And that Los of the temperature difference, the boiling point t of each effective solution can be estimate from the following equation. (1-14) 3. Preliminary Calculation of Heating Steam Consumption and Evaporation Water Volume of Each Effect The enthalpy balance formula of the first effect is The evaporation capacity Wi of the first effect can be obtained from the formula (1-15). If the concentration heat of the solution and the heat loss of the evaporator are taken into account in the enthalpy equation, the heat utilization coefficient η should also be taken into account. For the evaporation of general solution, η can be taken as 0.98-0.7 (where X is the composition change of the solution, expressed in mass fraction). Where: Di — heating steam quantity of the ith effect, kg/H, when no additional steam is extracted, R I — vaporization heat of heating steam of the first effect, kJ/kg; R 'I — vaporization heat of secondary steam of the first effect, kJ/kg; C PO — Specific heat capacity of feed solution, kJ/ (kg · ℃); C PW — specific heat capacity of water, kJ/ (kg · ℃); T I, t i-1 — boiling point of the solution of the i-th effect and the (i-1) -th effect, ℃; ηi — heat utilization coefficient of the ith effect, dimension is one. For the consumption of heating steam (live steam), it can be obtained by listing the enthalpy balance formula of each effect and solving it with the formula (1-2). 4. Distribution of Heat Transfer Area and Effective Temperature Difference of Evaporator in Each Effect The heat transfer rate equation for any effect I (1-17) Where: Q I — heat transfer rate of the ith effect, W; K I — heat transfer coefficient of the ith effect, W; Si — heat transfer area of the ith effect, m2; T I — heat transfer temperature difference of the ith effect, ℃. The purpose of effective temperature distribution is to calculate the heat transfer area Si of evaporation. Now take the triple effect as an example, namely (1-18) In the formula (1-19) (1-20) In multi-effect evaporation, in order to facilitate manufacturing and installation, evaporators with equal heat transfer area of each effect are usually used. If the heat transfer areas obtained from Equation (1-18) are not equal, the areas shall be redistributed according to the principle of each effective area. Effective temperature difference. The method is as follows: Let t 'denote the effective temperature difference when the effective surfaces are equal, then Compared with the formula (1-18), Add the three formulas in formula (1-22) to get In the formula, ∑ t is the sum of the effective temperature difference of each effect, which is called the total effective temperature difference, ℃. After the heat transfer area S is obtained from Equation (1-23), the effective temperature difference of each effect can be redistributed from Equation (1-22). Repeat the above steps until the obtained heat transfer area of each effect is equal, and the area is the required one. 3 Selection of evaporator As mentioned above, there are many types of evaporator structures. When selecting the type of evaporator or designing the evaporator, on the premise of meeting the requirements of production tasks and ensuring product quality, it is also necessary to take into account the simple structure, easy manufacture, convenient operation and maintenance, good heat transfer effect and so on. In addition, it is also necessary to have good adaptability to the process characteristics of the material to be evaporated,wiped film evaporator, including the viscosity, heat sensitivity, corrosiveness of the material and whether it crystallizes or scales.
    The climbing film evaporator is suitable for evaporating low-boiling point alcohols or low-boiling point volatile organic compounds; The falling-film evaporator is suitable for the concentration of water-soluble substances and the evaporation of materials which are not easy to crystallize or scab; The horizontal falling film evaporator is suitable for the evaporation of volatile organic compounds with medium boiling points such as ethanol; The natural internal circulation evaporator is suitable for the concentration and evaporation of general materials; The forced external circulation evaporator is suitable for the evaporation and crystallization of high-concentration and easy-to-crystallize materials; The combination of falling film and forced external circulation evaporator is suitable for the concentration and crystallization of low-concentration and easy-to-crystallize materials; The combination of natural circulation and forced external circulation evaporator is suitable for the crystallization of the thickener of the medium and low concentration materials which are easy to crystallize; The combination of forced external circulation and multi-effect evaporation crystallization is suitable for secondary concentrated crystallization containing high-boiling inorganic or organic substances; Selection Criteria for Common Evaporation Equipment Return to Sohu to see more Responsible Editor:. toptiontech.com

  • Precautions for use and maintenance of rotary evaporator _ vacuum pump
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    Original title: Precautions for use and maintenance of rotary evaporator Rotary evaporator is a kind of evaporation instrument widely used in laboratory. It is suitable for reflux operation, rapid evaporation of a large amount of solvents, concentration of trace components and reaction processes requiring stirring. The rotary evaporator system can be sealed and decompressed to 400 to 600 mm Hg; the solvent in the distillation flask is heated by a heating bath, and the heating temperature can be close to the boiling point of the solvent; at the same time, the rotary evaporator system can rotate at a speed of 50 to 160 revolutions per minute, so that the solvent forms a film and the evaporation area is increased. In addition, under the action of the high-efficiency cooler, the hot steam can be quickly liquefied and the evaporation rate can be accelerated. Usage of rotary evaporator: 1. Turn on the low temperature coolant circulation pump 。 Note that press the power button and then press the cooling button to start the cycle after the temperature is reduced to the required temperature. 2. Turn on the water pump to circulate water 。 3. Mount the distillation flask and secure with a clip 。 Turn on the vacuum pump and start to rotate when there is a certain vacuum. 4. Adjust the height of distillation flask ,cbd crystallization equipment, spin speed, and set that appropriate bath temperature. 5. Stop rotating after steaming ? Open the atmosphere again, then stop the water pump, and finally remove the distillation flask. 6 Stop the low-temperature cooling liquid circulating pump,wiped film distillation, stop the water bath for heating, turn off the circulating water of the water pump, pour out the solvent in the receiving bottle, and clean the buffer ball and the receiving bottle. Precautions for use of rotary evaporator: 1. When in use, a small vacuum should be pumped first. (About 0.03 MPa), and then start the rotation to prevent the distillation flask from falling off; when stopping, rotary vacuum evaporator ,decarboxylation after extraction, stop the rotation first, hold the distillation flask by hand, open the atmosphere, and stop the vacuum pump when the vacuum degree drops to about 0.04 MPa to prevent the distillation flask from falling off and sucking back. 2. Each interface ? Sealing surface, sealing ring and joint shall be coated with a layer of vacuum grease before installation. 3. Water must be added before the heating tank is powered on. ? Dry firing without water is not allowed. 4. If the vacuum degree is too low, pay attention to check the joints. Air tightness of vacuum tube and glass bottle. 5. During rotary evaporation of air-sensitive substances Connect a nitrogen balloon to the exhaust port, introduce a burst of nitrogen to discharge the air in the rotary evaporator, and then connect the sample bottle for rotary evaporation. After steaming, release nitrogen to boost the pressure, then turn off the pump, and then take down the sample bottle and seal it. 6. If the sample is very viscous ? Slow down the rotation speed and rotate slowly by hand to form a new liquid level to facilitate the evaporation of solvent. Maintenance method of rotary evaporator: 1. Carefully check the instrument before use to see whether the glass bottle is damaged and whether the interfaces are matched. Handle with care. 2. Wipe each interface with a soft cloth (napkin can be used instead), and then apply a little vacuum grease. Vacuum grease must be covered after use to prevent dust and sand from entering. 3. Each interface shall not be tightened too tightly, and shall be loosened and loosened regularly, so as to avoid seizure of the connector caused by long-term locking. 4. Turn on the power switch first, and then let the machine run from slow to fast. When the machine is stopped, the machine should be in a stop state, and then turn off the switch. 5. The Teflon switches at all places shall not be tightened with excessive force, which is easy to damage the glass. 6. After each use, all kinds of oil stains, stains and solvent residues left on the surface of the machine must be wiped with a soft cloth to keep them clean. 7. Loosen each PTFE switch after shutdown. The PTFE piston will be deformed if it is still in the working state for a long time. 8. Regularly clean the seal ring. The method is: take down the seal ring, check whether there is dirt on the shaft,50l rotovap, wipe it with a soft cloth, then apply a little vacuum grease, and reinstall it to keep the shaft and seal ring smooth. 9. The electrical part shall be free of water and moisture. Huagao Instrument returns to Sohu to see more Responsible Editor:. toptiontech.com

  • What should we pay attention to when using the reactor for cooling? _ Heat transfer
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    Original title: What should we pay attention to when using the reactor for cooling? When using the reactor cooling device, the user needs to pay attention to its refrigeration and heating operation, and pay attention to the operation within a reasonable temperature range, so as to avoid the reactor cooling failure caused by excessive temperature and pressure. Therefore, we need to understand clearly some points for attention in use. The heat transfer jacket for temperature reduction and cooling of the reaction kettle is generally made of common carbon steel, and is a container which is sleeved outside the barrel of the reactor to form a sealed space, so that the heat transfer jacket is simple and convenient. The jacket is provided with an inlet and an outlet for water vapor, cooling water or other heating and cooling media. (If the heating medium is water vapor, the inlet pipe shall be close to the upper end of the jacket, and the condensate shall be discharged from the bottom; if the heat transfer medium is liquid, the inlet pipe shall be placed at the bottom, and the liquid shall enter from the bottom and flow out from the top, so that the heat transfer medium can fill the whole jacket space. Sometimes, for larger vessels, in order to obtain better heat transfer effect, jacketed glass reactor ,nutsche filter dryer, a spiral guide plate is installed in the jacket space to reduce the flow area of the fluid in the jacket, improve the flow speed of the fluid and avoid short circuit, but the structure is more complex. When the diameter of the kettle is large or the pressure of the heat transfer medium is high, the welded semi-circular spiral pipe or spiral angle steel structure is often used to replace the jacketed structure. In this way, not only the flow velocity of the heat transfer medium can be increased and the heat transfer effect can be improved, but also the compressive strength and rigidity outside the reactor can be improved. After the cooling operation of the reaction kettle, water cooling (exothermic reaction) or air cooling can be carried out. The needle valve system is sealed. Only by slightly rotating the valve needle and pressing the cover tightly, good sealing can be achieved. It is forbidden to use excessive force to avoid damaging the sealing surface. After the reaction is finished, cooling is firstly carried out, then the high-pressure gas in the kettle is released, the pressure is reduced to normal pressure, and then the bolts are symmetrically and equally unscrewed and disassembled. Special attention shall be paid to the protection of the sealing surface during the removal of the cover. After each cooling operation of the reaction kettle, the residues on the kettle body and the kettle cover shall be removed. All sealing surfaces on the reaction kettle shall be cleaned frequently and kept dry. It is not allowed to use hard objects or soft objects with rough surface for cleaning. The agitator shall be disassembled for cleaning. The height of the cooling jacket of the reactor is determined by the heat transfer area, which is determined by the process requirements. However, it should be noted that the height of the jacket is generally not lower than the height of the feed liquid, and it should be about 50 ~ 100 mm higher than the liquid level in the reactor to ensure sufficient heat transfer. Various types of reactors are available for reactor cooling, so users must select the model according to their own working conditions in the early stage of selection, so as to avoid the situation of too large or too small selection. This article source network,thin film distillation, if has the right infringement, please contact Wuxi crown Asia to delete, thanks. Return to Sohu to see more Responsible Editor:. toptiontech.com

  • Secret Teach you how to distinguish the drill. Name of drilling rig and trolley? _ Impact
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    Originally published as Secrets..? Teach you how to distinguish the drill. Name of drilling rig and trolley? In the following, the professional terms that are easy to be confused in the rock drilling machinery commonly used in several mainstream mechanical drilling methods are sorted out, the terms such as top hammer impact drilling, down-the-hole drill, power head, trolley and drill carriage are explained and explained, and the names of commonly used drilling equipment are standardized and sorted out, which is conducive to the exchange of business and technology in the industry. 01. Necessity of product name identification In the industry of earthwork engineering, tunnel engineering and mining machinery, the names of "drill rig", "drill carriage" and "trolley" often appear. For down-the-hole equipment, most people call it "drill rig", and some people call it "drill carriage"; Top hammer type rock drilling equipment, which is called "rock drilling jumbo", "drilling rig" and "drilling rig" by some people, has no uniform and standardized name. The confusion in the use of product names is not conducive to the statistical management of social commodities, to the exchange of technology and business, and to the search of search engine nouns. Confucius said, "If the name is not correct, the words will not be correct, and if the words are not correct, the work will not be done." "Name rectification" is the need of social communication and the inevitable trend of social development. In this paper, the meaning and use scope of "drilling rig", "drilling rig" and "trolley" are discussed for the reference of producers, sellers, users and industry managers. Readers are welcome to discuss and correct the inappropriate points, so as to gradually standardize the names of products, so that each type of drilling machinery products has only one formal written name. Expand the full text 02. Drilling principle 2.1 Percussive drilling principle The percussive principle is applicable to the drilling of medium-hard and above rocks. The equipment for drilling by percussive method includes pneumatic rock drill, hydraulic rock drill, down-the-hole drill, steel cable percussive drill,rock drilling tools, etc. Percussion drilling can be divided into two types: down-the-hole drilling and top-hammer drilling. 2.1.1 Principle of down-the-hole drilling The principle of down-the-hole impact drilling is shown in Figure 1. The down-the-hole drilling is to install the impactor with impact effect at the bottom of the drill pipe and directly impact the drill bit to drill the hole. 2.1.2 Principle of top-hammer percussion drilling The principle of top hammer impact drilling is shown in Figure 2. Top hammer drilling is a way of drilling by installing the rock drill with impact effect on the top of the drill rod, directly impacting the drill rod, and transmitting the impact energy to the drill bit through the drill rod. 2.2 Cutting drilling principle The cutting drilling principle is shown in Figure 3. The cutting principle is applicable to drilling in soil or soft rock. The equipment for drilling by cutting method includes cutting drilling rig, rotary drilling rig, coal power station, coal mine roof bolter, etc. Because the cutting action is produced primarily by rotational torque, it is also referred to as rotary cut drilling. 2.3 Principle of rolling and drilling The rolling principle is applicable to the drilling of rocks below medium hardness. The roller drill applies the rolling principle to the drilling. The drilling process of the roller bit is shown in Figure 4. The drill is connected to the roller cone bit through the drill rod, and the drill rod is used to pressurize the bit into contact with the rock. At the same time, under the rotating action of the drill pipe, the cone with column teeth on the drill bit rolls, and through the column teeth in contact with the rock,dth hammer bit, the vibration impact and press-in force are transmitted to break the rock. This kind of drilling method is a combination of vibration impact crushing action and shear crushing action, so it is called rolling drilling, because the cone rolls on the rock, it can also be called rolling drilling. Coal mine roadheaders and tunnel boring machines all use the principle of rolling and crushing rocks. 2.4 Vibrating drilling principle The principle of vibration drilling is shown in Figure 5. Vibration drilling is applicable to drilling in soil or soft rock. The equipment for vibration drilling includes sonic drill, ultrasonic rock drill, etc. 2.5 Combined action of multiple principles Percussive, cutting, rolling, and vibrating methods are the four basic ways to drill holes in rock or soil. Actual drilling equipment is generally a combination of several principles. For example, hydraulic rock drill drilling is mainly based on impact action, supplemented by cutting action. Sonic drilling is based on the principle of vibration and the combined action of vibration, rotary cutting and rolling.
    03. Difference between drilling, perforation and rock drilling 3.1 Drilling Whether it is earthwork, tunnel engineering or mine excavation engineering; whether it is impact, cutting or vibration, as long as it is a drilling operation, it can be called drilling. 3.2 Perforation In rock excavation operations in open pit and underground mines, boreholes may also be referred to as perforations. 3.3 Rock drilling Percussion drilling and percussion-based drilling operations can be called rock drilling. Equipment using other drilling principles, such as cutting and vibrating drilling operations, cannot be called rock drilling. 04. Definition of down-the-hole hammer, rock drill and power head 4.1 Definition of down-the-hole impactor As the name implies, mining dth bit ,dth rock bit, the down-the-hole impactor is a tool that uses the principle of down-the-hole impaction to drill holes. Down-the-hole impactor is called impactor, English "Down The Hole Hammer" ", so it is also called down-the-hole hammer. GB/T 6247 defines the down-the-hole impactor as "a tool installed at the front end of the drill rod and diving into the bottom of the hole for rock drilling", which is completely accurate. 4.2 Definition of rock drill A drill that uses the principle of top hammer impact to drill holes is called a rock drill. Rock drill is divided into pneumatic rock drill and hydraulic rock drill; it can also be divided into hand-held rock drill, outrigger rock drill, guide rail rock drill and so on. GB/T6247 defines the rock drill as "a machine with percussive and slewing mechanism for drilling and drilling", which is generally correct, but the following three points are questionable: (1) It should not be called a machine, but an appliance or a tool, because the structure of the rock drill is relatively simple, there is no power part, and it needs to input hydraulic power or pneumatic power from the outside. (2) Emphasis should be placed on the impact action as the main and the rotary cutting action as the supplement. Machines and tools with rotary cutting as the main part and impact as the auxiliary part are generally called power heads, not rock drills. (3) It is not pointed out that the rock drill can only be used for top-hammer drilling. Although the down-the-hole impactor is a percussive drill, it cannot be called a rock drill. 4.3 Definition of power head The machine with output torque and rotating speed is called power head. The volume, weight, output torque and power of the power head are far greater than those of the rock drill. The power head is generally used for the drilling operation of rotary drilling rig, pipe shed drilling rig and anchor drilling rig. 05. Definition of drilling rig, drill rig and jumbo 5.1 Definition of drilling rig The connotation of drilling rig is the most extensive, which generally refers to all drilling equipment. Any equipment that can drill a hole in soil or rock can be called a drilling rig, whether it is percussive, cutting, rolling, vibrating or combined drilling, or mobile drilling equipment and fixed drilling equipment, such as oil drilling rigs, geological coring rigs, etc. GB/T6247 defines the drilling rig as "a machine that mainly relies on the slewing mechanism to drill rock holes", which greatly narrows the connotation of the drilling rig, thus excluding the down-the-hole percussive and top-hammer percussive drilling equipment from the drilling rig. This is inconsistent with the actual situation in our country. Most manufacturers and users in our country call the down-the-hole percussive drilling equipment as down-the-hole drill. Zhangjiakou Xuanhua, the famous "hometown of drilling rigs" in China, mainly produces down-the-hole percussion drilling rigs. It is suggested to be revised when GB/T6247 is revised. 5.2 Definition of drill jumbo Drill carriage is defined in GB/T6247 as "a carriage for rock drills to drill rock holes". According to this definition, only the rock drilling vehicle using top hammer percussive drilling can be called a drilling vehicle, and the down-the-hole drilling equipment can not be called a down-the-hole drilling vehicle. There is a contradiction between this and GB/T1590. In the category of drilling rig, GB/T1590 includes many product names, such as open-air down-the-hole drilling rig, open-air medium-pressure down-the-hole drilling rig, open-air high-pressure down-the-hole drill rig and open-air hydraulic down-the-hole drill rig. In English, words such as "drill rig" "and" drill Jumbo "" indicate drilling equipment without the meaning of "vehicle", while words such as "vehicle", "car" and "truck" indicate vehicles. In the world, there are few reports about using "vehicle" to describe self-propelled drilling equipment. "Rig" has the meaning of "drilling rig, drilling frame, drilling tower, platform", and generally refers to all drilling rigs in English.
    "Jumbo" has the meaning of "giant". Compared with hand-held rock drills and outrigger rock drills, single-arm, double-arm and three-arm rock drilling jumbos are of course giant, so "Jumbo" can be translated as rock drilling jumbo. The original meaning of "wagon" is "four-wheeled carriage", which also refers to a train or a carriage of a train. Later, wagon evolved into a substitute name for a car model. In the current English materials of foreign drilling rig companies, it is almost impossible to use "wagon" to refer to a drilling rig. It is suggested that the self-propelled drilling equipment with faster running speed should be called drilling rig, for example, the drilling rig that is converted from a car can be called drilling rig. 5.3 Definition of rock drilling jumbo Underground top hammer impact rock drilling equipment is called rock drilling jumbo. Underground construction equipment also includes anchor bolt jumbo, concrete spraying jumbo and prying jumbo, etc., which are called jumbos for short. The drilling jumbo has the narrowest connotation, only the underground top hammer impact drilling equipment. Underground top hammer impact rock drilling equipment can be subdivided into tunnel driving jumbo, roadway driving jumbo, mining jumbo and so on. Although "jumbo" also contains the word "car", it emphasizes the word "platform". On this platform, one or two or three or more drilling booms can be installed for drilling operation. The content of GB/T6247 does not include "rock drilling jumbo". In fact, the term "rock drilling jumbo" is widely used. It is particularly common in railway tunnel excavation and underground mining engineering, and has been established by usage. It is suggested that the drilling jumbo should be defined when the standard is revised in the future. Open-air top hammer impact drilling equipment is generally called drilling rig, not rock drilling jumbo, which is also established by usage. 06. Sum up The names of commonly used drilling equipment are arranged as follows: (1) Fixed drilling equipment can only be called drilling rig; (2) The drilling equipment using the roller bit can only be called a roller drill; (3) Rotary cutting drilling equipment shall be called drilling rig, such as cutting drilling rig and rotary drilling rig; (4) Equipment using power head for drilling shall be called drilling rig, such as pipe shed drilling rig and top drive drilling rig; (5) Down-the-hole percussive drilling equipment should be called down-the-hole drill; (6) Open-air top hammer percussive drilling equipment should be called open-air top hammer drilling rig; (7) Tunnel and underground top hammer percussive drilling equipment should be called rock drilling jumbo; (8) Drilling equipment modified from automobiles should be called drilling rig; (9) If the traveling speed is very slow, such as less than 10KM/H,overburden drilling systems, it should be called a drilling rig. Thank you for reading, remember to press the official account! Return to Sohu , see more Responsible Editor:. wt-dthtools.com

  • Stainless steel drilling is too difficult? What kind of drill is good? _ Yide
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    Originally published as Is it too difficult to drill stainless steel? What kind of drill is good? Nowadays, the application of stainless steel is more and more extensive, and a number of drill bits suitable for stainless steel have been developed for drilling in the market. Today, ZTE Yide Xiaobian will discuss with you about the drilling of stainless steel. The premise is that we must first understand the processing characteristics of stainless steel. The stainless steel material has strong plasticity and high toughness, but when drilling, the stainless steel surface has a large degree of hardening, the cutting temperature is high, and when drilling, the twist drill is surrounded by the hole wall around the stainless steel surface, it is difficult to dissipate heat, and it is very easy to stick to the drill bit. Therefore, stainless steel drilling requires that the drill bit shall have high hardness, good surface finish,dhd drill bit, and the vertex angle of the drill bit shall be larger than that of the ordinary drill bit (between 130135). Meanwhile, it shall be fully cooled, and the feed rate shall be greater than 0. 15 mm so as not to cut in the cold hardening layer as far as possible. When drilling stainless steel, the speed is reduced as much as possible, the drilling temperature is also reduced,dth drill bits, and the emulsion is used for drilling. Drill bits commonly used for stainless steel drilling are: high cobalt twist drill (M35 twist drill, M42 twist drill), of which M42 high cobalt twist drill has the best cost performance. In addition, a replaceable carbide crown bit can be used, but the price is higher. Cobalt-containing twist drill is a twist drill containing the chemical element cobalt (Co). The purpose of adding the chemical element cobalt (Co) is to improve the high temperature resistance and abrasion resistance of the twist drill, so that the drill hole can successfully penetrate the stainless steel surface. Cobalt-containing twist drills are divided into cobalt-containing and high-cobalt drill bits. The materials are M35 and M42. Cobalt-containing twist drills are harder than ordinary twist drills, but they are also fragile. Expand the full text Replaceable carbide crown bit is a new generation of drilling bit. It consists of a steel drill body and a replaceable solid carbide crown, and its machining accuracy is eight and a half kilograms. But that proces cost can be reduced and the drill yield can be improved because the tooth crown can be changed. This kind of drill can obtain accurate aperture size increment and has self-centering function, so the aperture machining accuracy is very high. Besides these two bits, Borehole Drill Bits ,mining drill bit, is there a stainless steel bit? Can you drill? Believe that many people have such an idea, ZTE Yide Xiaobian will use this video to verify everyone's idea. Poke the video Kangkang Established in 2012, Wuxi Zhongxing Yide, a 304 L stainless steel supplier, is located in the Andali Building near the Oriental Steel City in Wuxi, Jiangsu Province, a well-known stainless steel market in China, with excellent geographical location and convenient transportation. It is a comprehensive enterprise mainly engaged in low-carbon stainless steel, integrating warehousing, processing, trade and distribution. Wuxi Zhongxing Yide is mainly engaged in 304 L, 316 L, 317 L, 409 L, 436 L, 904 L, 301L and other low-carbon stainless steel plates, stainless steel coils, stainless steel strips and stainless steel flat steel, with a standing stock of more than 1000 tons of materials, complete specifications and sufficient supply. At the same time according to customer requirements to provide a variety of stainless steel plate processing services: Kaiping, slitting wire drawing, mirror, oil grinding, polishing, punching, bending, leveling, slitting, cutting,down the hole bit, rolling, punching and so on. Want to know more exciting content, come and pay attention to the official website and WeChat public account of ZTE Yide. Source: https://www.zxyd304l.com. WeChat official account: zxydbxg Return to Sohu to see more Responsible Editor:. wt-dthtools.com

  • The most complete knowledge of open-pit mining, mining people have collected! _ Blasting
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    Original title: The most complete knowledge of open-pit mines has been collected by miners! Strip mining is the extraction of valuable minerals from open pits. Mechanical mining: mining hard ore and rock, with deep-hole blasting and mechanical mining as the main means to obtain ore. Manual mining: Prohibited by An Wei Ban [2010] No.17 Civilization Order. Simulated appearance of open pit 1. Classification of closed circle and open-pit mine Closed circle: the plane closed curve of the surface of the open pit. It can be divided into hillside open-pit mine and sunken open-pit mine according to the topographic conditions of deposit burial and the surface closed circle of open-pit mining boundary. Above the surface closed circle of the hillside open-pit mine; Below the surface closed circle of the sunken open-pit mine. Expand the full text Sketch map of hillside open pit and sunken open pit A — hillside open-pit mine, B — sunken open-pit mine, 1 — elevation of surface closed circle 2. Three elements of open-pit mine Bench: The ore rock is divided into horizontal layers of a certain thickness, and the working levels form a ladder shape in space during the mining process. Each step is called a step, and its height becomes the step height. Bench slope: the inclined surface on the side of the bench facing the goaf. The angle between the inclined plane and the horizontal plane is called the bench slope angle. Platform (flat plate): The space on the horizontal plane between the slope bottom line and the slope top line of the step. The width between the slope bottom line and the slope top line is called the platform width. The platform for blasting, shoveling and transportation operations is called the working platform. The width between the blasting pile edge and the slope top line is called the working platform height. The platform for intercepting sliding rocks is called safety (cleaning) platform. 3. Mining technology of open-pit mine The mining technology of open-pit mine is relatively simple, mainly including drilling, blasting, mining, loading and transportation, and rock dumping. Next, we will talk about the mining technology of open-pit mines in detail. I. Perforation work Perforation is the first working procedure of open pit mining. In the whole process of open pit mining, the cost of perforation accounts for about 10%-15% of the total production cost. 1. Down-the-hole drill The down-the-hole drilling machine has the advantages of large drilling angle change range, high mechanization degree, reduction of auxiliary operation time, improvement of the operation rate of the drilling machine, flexibility of the down-the-hole drilling machine, light equipment weight and low investment cost, and particularly can control the ore grade by drilling various inclined holes, eliminate toes, reduce large blocks and improve the blasting quality. Therefore, the down-the-hole drill is widely used in small and medium-sized mines at home and abroad, which is suitable for medium hard rock drilling. 2. Rotary drill Rotary drilling rig is a new type of drilling equipment developed on the basis of rotary drilling rig, which has the characteristics of high drilling efficiency, low operation cost,DHD Drill bit, high degree of mechanization and automation, and is suitable for drilling operations of various hardness of ore and rock. At present, it has become a common drilling equipment used in open-pit mines all over the world. 3. Rock drilling jumbo Drill jumbo is a new type of drilling equipment with the development of mining industry. One or a plurality of rock drills are arranged on a special drill boom or a rack together with an automatic propeller, and a traveling mechanism is arranged, so that the operation of the rock drill is mechanized. II. Blasting work The purpose of blasting work is to break the hard solid ore rock and provide the excavation material with appropriate size for mining and loading work. In the total cost of open-pit mining, blasting cost accounts for about 15% -20%. The quality of blasting not only directly affects the efficiency of mining, transportation, coarse crushing and other equipment, but also affects the total cost of the mine. 1. Shallow hole blasting The diameter of the hole used in shallow hole blasting is small, generally about 30-75 mm,dth drilling hammer, and the depth of the hole is generally less than 5 meters, sometimes up to about 8 meters. If the drilling jumbo is used for drilling, the depth of the hole can be increased. Shallow-hole blasting is mainly used for the excavation of open-pit mines or quarries, caverns and tunnels with small production scale, secondary blasting, the treatment of new open-pit mine hills, the formation of hillside open-pit single-wall ditch transportation channels and other special blasting. 2. Deep-hole blasting Deep-hole blasting is a blasting method that uses drilling equipment to drill deeper boreholes as the charging space of mining explosives. The deep-hole blasting of open-pit mine is mainly the production blasting of bench. Drilling equipment for deep-hole blasting mainly includes down-the-hole drill and roller drill. It can be used to drill vertical deep holes or inclined blast holes.
    The charging of inclined blast holes is more uniform, and the blasting quality of ore and rock is better, which creates good conditions for mining and loading work. In order to reduce the seismic effect and improve the blasting quality, such measures as millisecond blasting in large area, interval charging in blastholes or bottom air interval charging can be taken under certain conditions, so as to reduce the blasting cost and obtain better economic benefit. 3. Chamber blasting Chamber blasting is a blasting method in which more or a large amount of explosives are loaded in the tunnel of the blasting chamber. Open-pit mines are used only during the capital construction period and under specific conditions, and quarries are used when conditions permit and when the demand for mining is high. 4. Multi-row hole millisecond blasting method In recent years, with the rapid increase of the excavator bucket capacity and the production capacity of the open-pit mine, the normal excavation blasting of the open-pit mine requires more and more blasting quantity each time. Therefore, large-scale blasting methods such as multi-row-hole millisecond blasting and multi-row-hole millisecond extrusion blasting are widely used in open-pit mining at home and abroad. Advantages of multi-row millisecond blasting: The blasting quantity at one time is large, the blasting times and the blasting avoidance time are reduced, and the utilization rate of the stope equipment is improved The broken quality of ore and rock is improved, Mining Drilling Equipment ,mining dth bit, and the large block rate is reduced by 40% -50% compared with the single-row hole blasting. The efficiency of perforating equipment is increased by about 10% -15%, which is due to the increase of working time utilization factor and the decrease of the number of operations of perforating equipment and filling area after blasting. Improve the efficiency of mining and transportation equipment by about 10% -15%. 5. Multi-row hole differential extrusion blasting method It refers to the multi-row millisecond blasting in the case of residual muckpile in the working face. The existence of the muck pile creates conditions for extrusion. On the one hand, it can prolong the effective action time of blasting and improve the utilization of explosive energy and crushing effect; on the other hand, it can control the width of the muck pile and avoid the scattering of ore and rock. The millisecond interval of multi-row hole millisecond extrusion blasting should be 30% ~ 50% longer than that of ordinary millisecond blasting, and 50 ~ 100ms is often used in open-pit mines in China. The advantages of multi-row hole millisecond extrusion blasting are as follows: (1) The ore rock crushing effect is better. This is mainly because the front is blocked by the slag heap, and each row of boreholes, including the first row, can increase the charge and be fully crushed under the extrusion of the slag heap; (2) The muckpile is more concentrated. For mines using railway transportation, the road can not be removed before blasting, so as to improve the efficiency of mining, loading and transportation equipment. The disadvantages of multi-row hole millisecond extrusion blasting are that the consumption of explosive is large, the working platform is required to be wider to accommodate the muck pile, and the height of the muck pile is large, which may affect the safety of excavator operation. III. Blasting measures near the slope With the downward extension of open-pit mine, the problem of slope stability has become increasingly prominent. In order to protect the slope, the blasting near the slope should be strictly controlled. According to the experience at home and abroad, the main measures are millisecond blasting, presplitting blasting and smooth blasting. 1. Adopt millisecond blasting to reduce vibration One of the main functions of millisecond blasting is to reduce the seismic effect of blasting. In order to give full play to the shock absorption effect of millisecond blasting, the key is to try to increase the number of blasting segments and control the millisecond interval. 2. Adopt presplitting blasting to isolate the slope. The presplitting blasting near the slope is to drill a row of dense parallel boreholes along the slope boundary, fill each hole with a small amount of explosives, and detonate before the excavation zone is blasted, so as to obtain a crack with a certain width and running through each borehole. Due to the separation of the excavation zone from the slope by the pre-fracture, the seismic wave of the subsequent excavation blasting will produce a strong reflection on the fracture surface, which will greatly reduce the seismic wave passing through it, thus protecting the slope. 3. Adopt smooth blasting to protect the slope. Smooth blasting near the slope is to drill a row of dense parallel boreholes along the boundary line, fill a small amount of explosives in the holes, and then blast after the excavation of boreholes, so as to form parallel rock walls along the dense boreholes. The difference between smooth blasting and presplitting blasting lies mainly in the initiation time. The initiation of the smooth blasthole is later than that of the previous rows of excavation holes, usually 50 to 75 ms later. In addition, another measure is to control the blasting of the last few rows of boreholes. The explosive quantity and resistance line of the last rows of boreholes near the slope should be reduced, which is called "buffer blasting", which can reduce the damage of drilling blasting to the slope.
    IV. Purchase, loading and transportation Mining and loading operation is to use loading machinery to excavate ore rock directly from the ground or blasting pile, and load it into the carriage of transport machinery or unload it directly to the designated place. It is the central link in the process of open-pit mining, and other production processes such as drilling and blasting, transportation and so on serve for mining and loading. Main mining and loading equipment: excavator, dragline, hydraulic shovel and rubber-tyred front loader. In the process of open-pit mining, the capital construction investment of mine transportation accounts for about 60% of the total investment of mine capital construction, and the transportation cost and labor volume account for more than half of the total ore cost and labor volume respectively, which shows the important position of transportation in open-pit mining. Transportation modes of open-pit mines: automobile transportation, railway transportation, belt transportation, slope skip lifting transportation and combined transportation, among which dump truck transportation is the most common. Mining and transportation are inseparable, and they influence and restrict each other. At present, the development trend of mining and transportation technology is mainly reflected in the large-scale of mining and transportation equipment, the integration and continuity of mining, loading and transportation links, and computer automation. 5. Rock discharge Rock dumping is the operation of the transport terminal, which transports the stripped topsoil and waste rock to the waste rock yard for disposal. Rock dumping process: rock dumping by railway transportation, road transportation and belt transportation 6. Dump Waste dump (waste rock dump): a place where stripped materials are piled up, which refers to the place where mining wastes are discharged in a centralized manner. According to the stacking sequence, the dump can be divided into single-bench dump, covering multi-bench dump and slope-pressing multi-bench dump. The dump is mainly divided into road transport dump, railway transport dump, belt transport dump and hydraulic transport dump according to the dumping process. Source: Mining Engineering Disclaimer: The content contained in this article is online information, and the copyright owner cannot be contacted. If there is infringement in the text and pictures of the article,Tapered Rock Bit, please contact the public number operator, WeChat ID: zjks2016, and we will delete it! Return to Sohu to see more Responsible Editor:. wt-dthtools.com

  • History of Russian (Soviet) Fighters: MiG 25 _ Mach _ American _ Blackbird
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    Original Title: History of Russian (Soviet) Fighter Development: MiG 25 Fighter When it comes to the fastest aircraft flying today, many people think of the SR-1 Blackbird strategic reconnaissance aircraft of the United States for the first time. In today's era when Mach 2 is everywhere and Mach 1 is not as good as dogs, all countries are studying higher and faster aircraft. The US Blackbird strategic reconnaissance plane has a maximum flight altitude of 300 meters and a maximum flight speed of Mach 3.3. This speed explains what is called the world's martial arts. It has never been shot down in more than 4,000 missile attacks. At that time, the Soviet Union, as a bitter rival of the United States, did not like the arrogant United States, so the MiG 25 came into being. Expand the full text How scary is the MiG 25? And how did you become the Blackbird's nemesis? The MiG 25 fighter uses a new aerodynamic layout different from conventional fighters, fastest dth hammer , with two-dimensional inlets on both sides, cantilevered high-wing twin vertical tails, and a simple straight-line fuselage shape, which further reduces the drag of the aircraft. The fuselage material of the MiG 25 must be resistant to high temperatures at speeds up to Mach 3.3 per hour. The fuselage surface of the fighter must be able to withstand the extremely high temperature of 300 degrees Celsius, in which conventional aluminum alloy simply can not withstand, in this case, the MiG 25 fighter has to use stainless steel with better high temperature resistance. It is said that when Israel saw the MiG-25, there was no way to intercept it, because at that time Israel's most advanced missile speed was less than Mach 3, and it could not catch up with the MiG-25 at all. This also surprised both Israel and the United States. After all, if the Soviet Union attacked it at that time, there would be no room for defense. Return to Sohu to see more Responsible Editor: (function() { function getBrandHtml() { var brands = [],dth button bits, html = ''; for(var i = 0; i < brands.length; i++) { var brand = brands[i]; if(brands.length i+1) { html+= ''+brand.name+''; } else { html+= ''+brand.name+'、'; } } return html; }; if(document.getElementById('linkBtn')){ document.getElementById('linkBtn').onclick = function() { $('#brands').removeClass('brand');$ ( '# tipInfo').text ( 'Real name responded'); $ ('#linkBtn').remove();$ ('.real-response .content').css('line-height', '20px');$ ('.real-response .time').css('line-height', '20px'); }; document.getElementById('brands').innerHTML = getBrandHtml(); }; })();。 wt-dthtools.com