Manufactured sand plant 32 FAQ
Manufactured Sand is more and more widely used for building materials, highway, railway, concrete mixing plant, and other industrial use. The manufactured sand plant 32 frequently asked questions that may help us to know more about the artificial sand making process.
1. What is manufactured sand?
Artificial sand is the gravel sand which made by sand making machine and other auxiliary sand plant equipment. The manufactured sand can be processed into different rules and size sand according to different technological requirements.
2. What equipment is required in a manufactured sand plant?
The manufactured sand plant usually needs a sand-making machine, vibrating feeder, jaw crusher, cone crusher, impact crusher, vibrating screen, belt conveyor, sand washing machine and other equipment. Various types of equipment for combination, which can meet the different process requirements of customers.
3. Advantages compared with natural sand
① supply stabilize
As a result of years of exploitation of natural sand, resources are becoming less and less, demand exceeds supply. The natural sand prices are soaring, and the supply and quality are not guaranteed. But there are many manufactured sand raw materials, such as construction waste, crushed stone tailings, waste materials, stone debris, stone slag, mine tailings, etc.
The price of artificial sand varies from place to place, but it is much cheaper than river sand. Compared with river sand, manufactures sand is cheaper not a few per ton. In addition, the profit of mechanism sand is also quite considerable, with a scale of 2,000 tons per day and according to the current market price, the monthly gross profit is expected to be more than 1 million yuan.
③ environmental protection
The traditional Manufactured sand plant will bring environmental problems such as dust pollution. But with the continuous improvement of the sand-making process, the production now basically adopts a fully closed structure, and every machine outlet is equipped with water spraying. Then the dust doesn’t spill out. While the dry process of environmental protection doesn’t need to wash, and not produce sewage, silt, dust, and other problems.
④ adhesion, life
When the particle size of manufactured sand is used for structural bonding such as cement, it tends to have better adhesion, better compression resistance, and longer service life.
4. What are the advantages of the dry process?
The main advantages of the dry process are:
① The moisture content of manufactured sand is low, generally less than 2%. The dry mixed mortar can be used directly.
② The content of stone powder in the finished sand can be adjusted and controlled. And centralized recovery can be used comprehensively to reduce dust emission.
③ Little or no water is used in the sand production process to save water resources and protect the environment.
④ Easy centralized operation and control, automatic management.
⑤ It is not affected by the dry and cold seasons and can be produced continuously throughout the year.
5. Why is the wet process less and less used?
The main reasons are:
① Consume a lot of water, 1-ton sandstone material needs to consume water 2-3.5 m³.
② The water content of the finished product sand is high, which must be dehydrated. If dry mix-use, it must drying again.
③ The fineness modulus of artificial sand is coarser and the sand yield is lower.
④ Producing a lot of sludge powder sewage, which polluted the environment. And the stone powder is not easy to recover.
⑤ Capital construction investment and the equipment type are many, the manufactured sand plant cost is high.
6) Failure to produce normally in dry areas or during freezing seasons.
6. What are the characteristics of the semi-dry sand making process?
The biggest characteristic of the semi-dry process is that the mud and stone powder on the surface of the raw materials are washed off with water. The parts or complete of finished sand is no longer washing, so the water consumption is relatively less. The loss of stone powder in the finished sand is less and the water content is lower. However, this sand manufacturing process needs more water resources, and sewage treatment equipment is still needed, although the size is much smaller. The investment cost is less than the wet method and more than the dry method. The content of finished sand and stone powder is between them, and the operation cost is between them.
7. What is artificial methylene blue (MB) value?
It can be used to judge whether the particle content in manufactured sand with a diameter of less than 0.075 mm is mainly soil or stone powder with the same chemical composition as the processed parent rock. Mb ≤1.4 which should be controlled below 1.0.
8. Why the finished sand should be humidified and mixed?
In the dry production process of machine-made sand, deal with the humidified and mixed can make the water content of manufactured sand reach the saturated surface dry state, which is beneficial to the control of the water consumption of subsequent concrete mixing. At the same time can reduce the process of transport segregation and dust.
9. Why is fineness Modulus unstable?
In the production process, the feeding lithology, water content, and gradation are easy to change. The screening process will also appear hole plugging, damage, and other problems. Crushing and dedusting equipment efficiency, parameters also are unstable, which easy to cause the sand fineness modulus instability.
10. The waste concrete, brick can be used for artificial sand?
The waste concrete, brick, and other industrial waste can make manufactured sand by manufactured sand plant equipment through the process of sorting, cleaning, crushing and screening. However, the current industry is mainly used for the production of recycled coarse aggregate.
11. What is the basis of the artificial sand making process?
Basis for selection of dry, wet and semi-dry artificial sand manufacturing plant:
Firstly, it depends on the area and water resources of the system, the cleanness of raw materials. And the specific requirements of aggregate, aggregate content and fineness modulus. If the original conditions allow, the first choice of the dry production process. Followed by the semi-dry production process, the last use of the wet production process.
Secondly, consider the equipment input, the size of the area, the production management difficult degree, the materials processing cost consideration. This condition is also the priority dry method, the next semi-dry method, finally is the wet method.
12. How to sample for artificial sand?
The general method for sampling manufactured sand is as follows:
①when sampling on the pile, the sampling site shall be evenly distributed. Before sampling, the surface of the sampling site shall be removed, and then approximately 8 equal parts of sand shall be taken from different sites to form a group of samples.
② when taking samples from the belt conveyor, the feeder is used to take 4 parts of sand at the discharge place of the tail of the belt conveyor，at the same time to form a group of samples.
③ when taking samples from trains, automobiles and cargo ships, 8 parts of sand of approximately equal quantity are drawn from different parts and depths to form a group of samples.
13. Methods of detection the stone powder content
There are two kinds of testing methods for the content of the machine-made stone powder. One is the water washing method and the other is a dry screening method. American ASTMC136 or AASHTOT27 are suitable for dry screening methods. ASTMC117 or AASHTOT11 are suitable for the water washing method. However, in our country, the dry sieve method is always used in cement concrete aggregate or asphalt pavement aggregate. The pass of 0.075 mm sieve is not determined by water washing, so its accuracy is poor. The dry-sieving method is mainly applicable to the aggregate used in cement concrete.
14. The methods of separating stone powder
From the development of industrial technology and equipment: At present, the main methods of removing excess stone powder in the original sand are water washing hydraulic classification, high-frequency screening mechanical screening, and dust removal pneumatic classification.
15. How to adjust the size of manufactured sand?
The particle grading of the sand can be realized by adjusting feed grading, feed rate, rotary speed of crusher and screen size.
16. What factors affect the grain shape of mechanism sand?
The factors as follow:
① The raw material which unfavorable to obtain better grain shape.
② Type of crushing equipment, impact crusher has a better forming effect.
③ The type of screen equipment, such as square hole which is better to control the grain shape.
17. Why “to break the mill, more broken less mill”?
Because the crushing energy utilization rate is higher than the grinding. More crushing and less grinding can help save energy, but it can not be completely replaced by grinding. Because the energy utilization of both materials changes in the reverse direction as the particle size becomes smaller.
18. The characteristic of impact crusher
“Stone beating Stone” is suitable for abrasive materials above medium hardness, such as basalt, etc. Under this working condition, the finished product has better grain shape and contains more powder. “Stone beating Iron” is suitable for abrasive materials below medium hardness, such as limestone. These working conditions, high crushing efficiency, wear and tear around the plate higher costs, product slightly worse grain type. The most serious wear of “Stone beating Iron” should be the anvil, so its structure design and casting technology are also important factors affecting the efficiency of sand making machine.
19. Why use double motors in sand processing equipment?
Use dual motors have two main purposes:
① The double motor ensures the balancing force of the main shaft.
② Ensure speed, energy in the transmission process will be lost. The double motor to ensure high power, ensure speed.
20. How to solve the large deviation of the two working currents?
In dual-drive equipment, the current of one motor is lower than the other is called inert reaction. The deviation should not be more than 10%. It is usually solved by adjusting and equalizing the tension of the transmission belt, checking the cleanliness of the terminal, checking the soft start and so on.
21. Why the impeller rotor have to correct static balance
Without proper static balance correction of the impeller rotor, the unbalance of the rotor is large. And the centrifugal force produced during operation will lead to the problems of abnormal vibration and invalidation, abnormal wear of the rotor and excessive noise. According to the industry standard, the balance grade of the impellers and rotors is G16.
22. Basic steps of correct balance the sand-making machine
After changing the wear-resistant parts of the impellers, the basic steps for correcting the static balance of the impellers are as follows:
① Clean up the stone materials, old wear parts and sundries on the rotors and accessories, and confirm that they can continue to be used.
② Reinstall the wear-resistant parts and install the rotor on the balance fixture.
③ Determine the unbalanced counterweight and position.
④ Check the balance of the already balanced rotor.
23. Factors affecting the efficiency of impact sand maker?
① Characteristics of raw materials: low hardness, low strength, good crushing, High sand-making efficiency.
② Influence of the water content of the crusher material. The sand yield will decrease when the water content is higher.
③ Feeder size. Generally speaking, the larger the feed, the better the crushing effect, but there is an extreme point.
④ Impeller speed. Generally, the higher the speed, the better the crushing efficiency.
24. Why vibrate more when sand maker starts?
Because of the starting operation, the rotor does not form a uniform lining and imbalance. So generally at the beginning of several pieces of fine, if the start into the coarse material will continue to vibration for several hours until the rotor to form a uniform lining.
25. What types of vibrating screens in the sand plant?
The sieving equipment: cylinder screen, circular vibrating screen, linear vibrating screen, high-frequency screen, and probability screen. The circular vibrating screen and linear vibrating screen are more common.
26. What factors can cause screen plugging?
① A lot of sand particles at the critical separation point
② Many flake materials in the sand material. The flake materials can not be screened smoothly in the sieving because of the reasons for rock crushing or the gravel sand material itself.
③ There is more mud in the aggregate.
④ The moisture content of the aggregate is high.
27. What is the reason the screen easy to wear?
The main causes of screen breakage are:
① The quality or material of the screen is not up to standard.
② Tension of the screen is not strong enough to cause the screen to quiver, which usually crusher or damage along the edge of the screen or at the edge of the pack.
③ Vibration amplitude of the sieve is too small, which causes the stone particles to pile up on the sieve and quickly damage the sieve.
28. What is the relationship between fineness modulus and screen size?
At present, the fineness modulus of machine-made sand is 2.6-3.0. It generally recommends using a screen size of 3.0mm or 3.5mm. If the content of stone powder is large, consider using a 2.8 mm screen. If it reaches about 2.3, consider a long screen, such as 1.7 X5 or 1.9 X5 screen size. Screen types generally try to choose a square mesh screen, which is very beneficial to the control of particle shape. circular vibrating screen or long screen as little use as possible.
29. What are the wear parts of vsi crusher?
Standard wear parts are cylindrical roller bearings, deep groove ball bearings, thrust ball bearings, expansion sleeve, conveyor belt, oil seal, o-ring.
Non-standard wear parts are: the upper sleeve, the lower sleeve (the lifting part of the hopper) , shock absorber rubber, roller retainer, upper / lower runner plate, impact block, distributor cone, wear-resistant plate, casting head, feeding ring, feeding pipe, upper / lower hitting guard plate, hopper lining ring, distributor plate, Bulk Material Plate (cone) , perimeter guard plate.
30. Why choose a wheel sand washing machine in the wet process?
The wheel sand washing machine has the advantages of simple structure, lower failure rate than the spiral sand washing machine. Less loss of fine sand and stone powder, better gradation of manufactured sand, easy control of fineness modulus and stable quality.
31. What are the types of rocks in nature?
There are three types of rocks in nature:
The first type is magmatic rock (igneous rock) which formed by the eruption of magma, generally hard and uniform.
The second type is sedimentary rocks, which form by a series of geological processes such as weathering, transportation, deposition, and diagenesis.
The third type is metamorphic rocks, which form on the basis of the existing rocks after metamorphism and mixing and have both the above-mentioned rocks and their own characteristics.
32. Which rocks can be used for artificial sand produce?
The raw materials of manufactured sand are usually granite, basalt, river pebble, cobble, Andesite, rhyolite, diabase, diorite, sandstone, limestone and so on. The mechanical sand produced by this method is different in strength and use according to the rock type.