Mechanism sand professional knowledge 33 ask, you do not understand can not!
1. What is machine sand?
Answer: machine sand is to point to pass make sand machine and the sand that other accessory equipment processes and becomes, can according to different craft requirement process the sand of different rule and size.
2. What equipment is usually required for mechanical sand production line?
Answer: machine sand production line usually needs sand machine, vibration feeder, jaw crusher, cone crusher, impact crusher, vibrating screen, belt conveyor, sand washing machine and other equipment, according to different technological requirements, various types of equipment to combine, to meet the different technological requirements of customers.
3. Advantages of machine sand over natural sand
A: 1) stable supply side
Due to years of exploitation, natural sand resources are becoming less and less. But the mechanism sand raw material is sufficient, the city construction waste (construction garbage), the crushed stone tail material, the leftover material, the stone chip, the stone slag, the mine tailings and so on May use as the mechanism sand raw material.
The price of machine sand is different in each place, but basically than river sand is much cheaper, compared with river sand, machine sand is 20 yuan or so per ton cheaper. In addition, the profit of machine sand is quite considerable. Based on the scale of 2000 tons/day and the current market price, the monthly gross profit is expected to be more than 1 million yuan.
3) environmental protection
Traditional mechanical sand production does bring about environmental problems such as dust pollution, but with the continuous improvement of sand production technology, now the production basically adopts a fully closed structure, and each machine mouth has a water spray setting, dust does not overflow, and the environmentally friendly dry process, does not need washing, does not produce sewage, silt, dust and other problems.
4) adhesion and service life
When the granule of mechanical sand is used for cement and other structures bonding, it often has better adhesion, more compression resistance and longer service life.
What are the main advantages of the dry process?
Answer: the main advantages of dry production process are:
1) the moisture content of the produced mechanical sand is low, generally less than 2%. Commercial mixed dry mixed mortar can be directly used.
2) the content of stone powder in the finished sand is adjustable and controllable. Centralized recovery can be comprehensively utilized to reduce dust emission.
3) little or no water is used in the production process to save water resources and protect the environment.
4) easy to centralize operation control and realize automatic management.
5) free from the influence of drought and cold seasons, it can produce continuously all year round.
5. Why are wet-process processes less and less used?
Answer: the main reasons are:
1) a large amount of water is consumed. 1t of sand and stone needs 2-3.5m of water.
2) products with high sand water content should be dehydrated and re-dried for dry mixing.
3) product sand fineness modulus is thick, sand yield is low.
4) produce a large amount of mud powder sewage, polluting the environment, and stone powder is not easy to recycle.
5) infrastructure investment and various types of equipment, high production cost of machine-made sand.
6) it cannot be produced normally in dry areas with little rain or in freezing seasons.
6. What are the characteristics of semi-dry sand process?
Answer: the semi-dry production process is relatively wet production process, the biggest characteristic is to wash off the surface of sand raw material mud and stone powder, finished sand part or all no longer for washing, so the water consumption is relatively less, finished sand in the stone powder loss, water content is lower. But this sand and stone production process still needs more water resources, sewage treatment equipment must be equipped, but the specifications are much smaller. Its investment cost is less than wet method, more than dry method, the content of finished sand powder is between the two, the operating cost is between the two.
7. What is the MB value?
Answer: it is used to determine whether the content of particles smaller than 0.075mm in the machine-made sand is mainly soil or stone powder with the same chemical composition as the processed parent rock. The methylene blue value of machine sand should be MB≤1.4 and should be controlled below 1.0.
8. Why should the finished sand be humidified and mixed?
Answer: in the production process of mechanical sand dry method, the moisture content of mechanical sand and gravel can reach the state of saturated surface dry, which is conducive to the control of water consumption for subsequent concrete mixing and can reduce segregation and dust in the transportation process.
9. Why is the modulus of fineness of mechanical sand unstable?
Answer: lithology, moisture content and gradation of feeding materials are easy to change in the production process, and problems such as plugging holes and damage may occur in the screening process. The efficiency and parameters of crushing and dedusting equipment are also unstable, which may easily lead to unstable modulus of fineness of mechanical sand.
10. Can waste concrete and masonry be used for sand production?
Answer: waste concrete, brick and industrial waste slag after special equipment through sorting, cleaning, crushing, screening and other technological processes, the production of mechanical sand. But the current industry is mainly used to produce recycled coarse aggregate.
11. What is the basis of the artificial sandstone production process?
Answer: selection of dry, wet, semi-dry artificial sand production process basis:
1) firstly, it depends on the area and water resource situation of the mechanical sand and stone system, the cleanliness of raw materials, and the specific requirements on aggregate, the content of mechanical sand and stone powder, and the modulus of fineness. If the original conditions are allowed, the first choice is dry production process, followed by semi-dry production process, and finally wet production process.
2) in terms of equipment input, floor area, production management difficulty and processing cost of sand and stone, dry method is also given priority, followed by semi-dry method and wet method.
12. How to sample machine sand?
Answer: the general method of mechanical sand detection and sampling is:
1) when sampling on the material pile, the sampling parts shall be evenly distributed. Before sampling, the surface of the sampling area was eradicated, and then roughly equal parts of sand were extracted from different parts to form a group of samples.
2) when sampling from the belt conveyor, use the feeder to regularly extract 4 equal parts of sand at the discharge point of the tail of the belt conveyor to form a group of samples.
3) when sampling from trains, automobiles and cargo ships, roughly equal amounts of sand are extracted from different parts and depths to form a group of samples.
13. What are the main methods to detect the content of mechanical sand powder?
Answer: there are generally two test methods for the content of mechanical stone powder: washing method and dry screen method. The representative one is American ASTMC136 or AASHTOT27, which is suitable for dry screen, ASTMC117 or AASHTOT11, which is suitable for water screen. However, in China, cement concrete aggregates or asphalt pavement aggregates are always directly used by dry screen method. The 0.075mm screen is not determined by washing through the amount, so the accuracy is poor. Dry screen method is mainly used for cement concrete aggregates, and should be combined with the results of methylene blue value comprehensive evaluation.
14. What are the main methods of stone powder separation?
Answer: from the perspective of the development of industrial process equipment, the current methods to remove the excess stone powder in the undisturbed sand mainly include water washing hydraulic classification method, high frequency mechanical screening method and wind power classification method for powder selection and dust removal.
15. How to adjust the grading index of mechanical sand particles?
Answer: mechanical sand particle gradation can be achieved by adjusting feed gradation, feed amount, crusher speed, screen size and other aspects.
16. What factors affect the mechanism of sand grain shape?
A: the factors that affect the sand grain shape are as follows:
1) the lithology of the source rock, such as the development of joints, is not conducive to better granulation.
2) type of crushing equipment, impact crusher forming effect is better.
3) mesh type, such as square hole, has better control of grain shape.
17. Why "wear out more wear out less"?
Answer: because the energy efficiency of crushing is higher than that of grinding, more crushing and less grinding is conducive to saving energy, but it cannot be completely replaced by crushing, because the energy utilization of both changes inversely as the particle size of materials decreases.
18. What are the characteristics of impact breaking "stone beating stone" and "stone beating iron"?
Answer: "stone to stone" is suitable for hard above abrasive materials, such as basalt. "Stone stone" under the working conditions of the finished product granule type is better, containing a little more powder. "Stone iron" is suitable for materials with low abrasion property under medium hardness, such as limestone. Under the working condition of "stone beating iron", the crushing efficiency is high, the wear cost of the circumferential protection plate is high, and the finished product grain type is slightly poor. "Stone iron" wear should be the most serious anvil, so its structure design and casting process is also an important factor affecting the efficiency of sand machine. In addition, "stone stone" for plastic, "stone iron" for sand.
19. Why is the impact breaker (sand machine) equipped with double motor?
Answer: the use of dual motor has two main functions:
1) the dual motor ensures the balanced stress of the spindle.
2) ensure the speed, the energy will be lost in the process of transmission, double motor to ensure the high power, ensure the speed.
20. How to solve the large deviation of working current between them?
Answer: dual drive equipment, the current of a motor than another low phenomenon called inert reaction, deviation requirements should not be greater than 10%; Generally by adjusting the tension of the transmission belt and make it equal, check the terminal cleanliness, check the soft start problems and other methods to solve.
21. Why should the impeller and rotor be corrected for static balance?
Answer: impeller rotor does not carry out appropriate static balance correction, rotor unbalance is larger, the centrifugal force generated in the process of operation will lead to abnormal vibration and failure of the equipment, abnormal wear of the rotor, too much noise and other problems. According to the industry standard, the impeller rotor balance grade of impact sand machine is G16.
22. What are the basic steps of balancing the sand machine?
Answer: impact sand machine impeller rotor replacement wear-resistant parts, impeller rotor correction static balance of the basic steps are:
1) clean the sand and stone materials, old worn parts and sundries on the rotor and accessories, and confirm that they can continue to be used.
2) re-install the wear-resistant parts and install the rotor on the balance fixture.
3) determine unbalanced weight and position.
4) review the balanced rotor balance.
What factors affect the efficiency of impact sand machine?
A: 1) characteristics of raw materials. Material hardness, low strength, good crushing, high sand production efficiency.
2) influence of water content of broken materials. Sand production decreases when water content is higher.
3) size of feeding amount. Generally speaking, the larger the amount of feed, the better the crushing effect, but there is an extreme point.
4) rotation speed of impeller. Generally, the higher the rotation speed, the better the crushing efficiency.
24. Why does the impact sand machine vibrate more when it starts running?
Answer: because begin to run, the rotor inside did not form uniform material line and unbalance is caused by, so general at the beginning must enter several square fine material, if begin to enter coarse material will continue to vibrate a few hours, until the rotor inside the formation of uniform material line.
25. What type of vibrating screen is currently used for mechanical sand screening?
Answer: mainly used for sand production screening equipment is: bar screen, cylindrical screen, circular vibrating screen, linear vibrating screen, high frequency screen and probability screen six types, bar screen is mainly used for soil removal process, circular vibrating screen, linear vibrating screen is more common.
26. What factors can cause screen plugging?
Answer: 1) sandstone contains a large number of critical separation point sandstone particles.
2) there are more sheet materials in sand and stone; Due to the reason of rock breaking or sand and stone itself, there are more flake materials in sand and stone, and the flake materials in screening cannot be sifted smoothly by themselves.
3) more mud in sand and stone.
4) high water content in sand and stone.
27. What are the main reasons why the screen is easily broken?
Answer: the main reasons why the mesh is easy to break are:
1) unqualified screen quality or material.
2) the mesh is not tight enough, so as to cause the vibration of the mesh, usually along the edge of the mesh or the edge of the cladding laminate fracture or damage.
3) the vibration amplitude of the screen is too small, resulting in the accumulation of sand and gravel particles on the screen and rapid damage to the screen.
28. What is the relationship between fineness modulus and mesh size?
Answer: currently, the modulus of fineness of mechanical sand is generally required to be 2.6-3.0. It is generally recommended to use screen size of 3.0mm or 3.5mm. If the content of stone powder is more, you can consider using 2.8mm screen; If you reach about 2.3, consider a long screen such as 1.7X5 or 1.9X5. The type of screen as far as possible to choose square hole screen, this is very beneficial to the shape control; Round hole mesh or long screen as far as possible to use; It is also necessary to monitor whether the mesh is broken and affect the modulus of fineness.
29. What are the wearing parts of impact sand machine?
A: the standard wearing parts are: cylindrical roller bearing, deep groove ball bearing, thrust ball bearing, expansion sleeve, conveyor belt, oil seal, o-ring seal.
Non-standard wearing parts include: upper shaft sleeve, lower shaft sleeve (lifting part of the feeding hopper), damping rubber, flailing wheel retainer ring, upper/lower runner plate, impact block, material splitting cone, wear-resistant plate, throwing head, material cutting lining ring, feeding tube, upper/lower striking protection plate, hopper lining ring, material splitting plate, bulk material plate (bulk material cone) and peripheral protection plate.
30. Why is wheel sand washing machine generally used in wet process production?
Answer: wheel sand washing machine structure is simple, the failure rate is far lower than the spiral sand washing machine, and in the washing process, fine sand and stone powder loss is less, the output mechanism sand grading is better, fineness modulus is easy to control, the quality is stable.
31. Apparent density of mechanical sand, loose bulk density, etc.
Answer: the apparent density of machine-made sand should not be less than 2500kg/m3; The density of loose stacking should not be less than 1400kg/m3; No more than 44% voids.
32. What kinds of rocks are there in nature?
A: there are three types of natural rocks:
The first is magmatic rocks (igneous rocks), formed by the eruption of magma, generally hard, uniform texture.
The second type is sedimentary rocks (hydrogenic rocks), formed by a series of geological processes such as weathering, transportation, deposition and diagenesis.
The third type is metamorphic rocks, which are formed after metamorphic and mixed action on the basis of existing rocks.
33. Which rocks can be used for mechanical sand production?
Answer: the sand-making raw material of machine sand and stone (gravel) usually USES granite, basalt, river pebble, cobble, andesite, rhyolite, diabase, diorite, sandstone, limestone and other varieties. The manufactured sand is classified according to the type of rock and varies in strength and use.