The Basic Principle of Magnetic Separation

Because of the different magnetism among the minerals, the magnetic force they bear is also different when they enter the magnetic field of the magnetic separation equipment (magnetic separator) , and thus the trajectories is different. And finally the minerals will be divided into magnetic product and the non-magnetic product (or ferromagnetic products and products with weak magnetism), achieving magnetic separation.
Mineral magnetic differences are the basis of magnetic separation. The magnetism of minerals can be measured and the minerals can be divided into three categories according to the degree of magnetic strength of the mineral : (1) strong magnetism minerals, such as magnetite, pyrrhotite, the number of such minerals is small; (2) weak magnetism minerals, such as hematite, limonite, ilmenite, psilomelane pyrolusite, garnet, the number of these minerals is larger; (3) non-magnetic minerals, most of the non-metallic minerals and non-ferrous minerals belong to this category. In the magnetic field of the magnetic separator, the ferromagnetic minerals suffer the maximum magnetic force, the weak magnetism minerals suffer smaller magnetic force and the non-magnetic minerals bear no magnetic force or weak magnetic force.
The magnetic field of the magnetic separator is a necessary condition of the magnetic separation. The magnetic field can be classified into the uniform magnetic field and nonuniform magnetic field. And the degree of nonuniformity of the magnetic field can be measured with the magnetic field gradient, which is the changing rate of the magnetic field strength along the space, i.e. the unit length variation amount of the magnetic field strength. The greater the magnetic field gradient is, the greater the degree of nonuniformity of the magnetic field will be, that is, rate of change of magnetic field strength along the space is large. The magnetic force that the magnetic ore particles bear is proportional to the product of the magnetic field strength and the magnetic field gradient. If the magnetic field gradient is equal to zero (in the uniform magnetic field, no matter how high the magnetic field strength is, the magnetic field gradients are equal to zero) and then the magnetic force that the magnetic mineral grains stand is zero and the magnetic separation can not be carried out.

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The Performance Features and Overhaul of Jaw Breaker

From the introduction to obtain the stability of the market, as for the jaw crusher, there are a lot of technological innovation and improvements. After the comprehensive combination of the performance of other crushing equipment, the following aspects are the performance characteristics of the jaw crushers:
1. Crushing chamber of the jaw breaker is deep and there is no dead zone, which increases the feeding capacity and output; large crushing ratio and uniform particle size;
2. It is easy to adjust the Gasket-discharge opening, reliable and convenient, large adjustment range, increasing the flexibility of the device;
3. Lubrication system is safe and reliable; it is easy to replace the parts; maintenance workload is small; simple structure, reliable operation, low operating costs.
4. Energy-saving: the energy-saving of the stand-alone can be reach 15% to 30%, the system can save more than doubled; the adjustment range of the discharging opening is large, which can meet the different requirements of users ; low noise, less dust.
The overhaul of the jaw crusher: after working for a period of time, any machinery needs maintenance, the damaged parts need replacing and the seriously worn ones need maintenance, which is the way to keep the long service life of the machine. Jaw crusher is to be overhauled according to the way of maintenance. In order to ensure the normal work of the jaw crusher, in addition to the proper operation, it is necessary to conduct the planned maintenance, including routine maintenance checks, minor repairs, medium repair and overhaul.
(1) Minor repairs: the main contents include the check and fix of the adjusting device, the gap of high-speed discharge opening and the replacement of the worn liner. Overhauling the transmission parts, lubrication systems and replacing the lubricants. The cycle of the minor repair is about 1-3 months.
(2) Medium repair: apart from all the work of minor repairs, the medium repair also includes the replacement of the thrust plate, lining, inspection and repair of bearing bush. Repair cycle is generally about 1-2 years.
(3) Overhaul: in addition to the work of medium repair, it includes the replacement of the eccentric shaft and moving jaw mandrel, the casting of the Babbitt metal on the rod head and the replacement or repair of all worn parts. Generally, overhaul cycle is about five years.

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The Optimum Time for Feeding of Rotary Kiln

Due to the reliable production and the wide application range, the rotary kiln is favored by the majority of customers. However, it is important to know some professional knowledge before operating the rotary kiln. Just taking the feeding of the rotary kiln as an example, what is the best time of the feeding?
Before the feeding, the burning zone and calciner in the rotary kiln should be fully preheated kiln, when increasing the air drafting in the kiln end, the oil injection of the kiln head and calciner should generally be appropriately increased so that the coal powder fire. When feeding, the operator must master the time lag between the ventilation and feeding. If the ventilation time is too early, the preheater temperature of the rotary kiln will be too high; if the ventilation is too late, the materials sedimentation could easily lead to the clogging. Generally, the feeding is conducted when the negative pressure is up to 1500pa, if the temperature is too high, the re-start cannot be conducted until the temperature is down. When feeding, in a short period of time, there are many projects needing operation, which should be operated in strict accordance with the feeding operating procedures. In order to ensure that the air volume and speed of the preheater system are relatively abundant, the operator should add the wind to the required amount of wind of the cooler in advance. In this case, in order not to make the kiln head generate positive pressure, the operator should increase the opening of the exhaust fan damper accordingly Kiln opening. Once the kiln begins to open the ventilation, this will keep the kiln head in a slight negative pressure and at the same time prevent the rotary kiln system from too high a degree of vacuum.
In addition, in order to make the coal powder realize the complete combustion, it is necessary to keep the appropriate flame shape and continue to retain and increase the appropriate fuel injection of the kiln head.

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The Three Types of Wet Permanent Magnetic Separator

The mineral that the magnetic separator can sort includes magnetite, limonite, hematite, manganese, siderite, ilmenite, wolframite, manganese ore, manganese carbonate ore, metallurgical manganese ore, manganese oxide, iron sands, kaolin and rare earth mine etc. The magnetic separation process is operated in the magnetic field of magnetic separator, with the help of magnetic force and the mechanical force on the role of the ore particles to achieve sorting. The ore particles with different magnetism moves along a different trajectory, sorting two or more separate products.
Wet permanent magnetic drum magnetic separator is a kind of magnetic separator widely used in the iron ore processing plant, which is suitable for the sorting of minerals with strong magnetism. In accordance with the tank structure type, magnetic separator can be divided into co-current, counter-flow, semi-counter flow. The selected size of these three kinds of magnetic separator is as follows: co-current tank ≤ 6mm, countercurrent tank ≤ 1.5mm and semi countercurrent tank ≤ 0.5mm.　
The processing capacity of the concurrent magnetic separator is large, which can not only be used for the rougher flotation and selection of the ferromagnetic materials with coarser granularity, but also is suitable for the concatenated work. When the feeding of concurrent magnetic separator is large, the magnetic mineral grains tend to lose in the tailings. Therefore, the operators should strengthen the operations management and control of the lower level of the pulp.
Counter-current magnetic separator is suitable for the roughing and scavenging of the fine-grained strong magnetic minerals. The recovery rate is higher, but a lower concentrate grade. Coarse material is easy to deposit to plug sorting space, thus the countercurrent magnetic separator is not suitable for the handling of coarse materials.　
Semi-current magnetic separator can not only obtain the high-quality iron ore concentrate, but also get a good recovery rate; therefore, the semi-current magnetic separator has been widely used in the production practice. It is suitable for the roughing and selection of the mineral whose particle is less than 0.5 mm and it can be used in series and parallel of several machines to achieve multiple scavenging and selection.

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The Common Ways to Improve the Production Capacity

According to the noise of ball mill, the operator can adopt electric ear to control electromagnetic vibrating feeder or belt feeder and control the right amount of the grinding material in the mill and automatically adjust the material to be evenly added, making the materials amount always maintain the best condition to improve the outputof ball mills.
Strengthening the ventilation .
The ball mill has a certain wind speed so that the fine powder generated in the grinding process can be promptly flowed away by the airflow, which will reduce the buffering effect of the fine powder and improve the grinding efficiency. And the product quality will not be affected.
The ventilation speed in the ball mill will be different due to the different materials to be grinded. Generally, the ventilation speed is 0.3-1.0m / s.
When the ball mill is well-ventilated, the water vapor in the mill will be discharged in time so that the holes of the compartment plate will not be clogged and the adhesion phenomenon of the mill boday is also reduced, which can reduce the temperature inside the mill and is conducive to the operations and improve product quality.
The production of high strength grade cement should choose the low-speed, otherwise, selecting the bigger speed.
Water spray in the mill.
When grinding cement, it will produce a lot of heat, which is harmful for the quality of cement and grinding efficiency and affect the production.
Spraying water that has been atomized with high-pressure air into the mill can effectively take away the heat inside the mill, realizing the cooling of the ball mill.
Water is a surface-active substance, which is easy to make the agglomerates of particles achieve the disintegration.
The water spray is determined according to the temperature inside the mill. Generally, when the temperature is below 1000C, there is no need to spray water.
In addition, the amount of water spray should be decided according to the temperature of the grinding clinker, which maybe accounts for about 1% to 2% of the amount of the cement. The water sprayed into the mill should be completely evaporated without residual moisture.

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Large Noise And Poor Manufacturing Precision

Large noise. The problem of large noise is one of the general problems for the domestic vibrating screen. The noise is usually more than 96dB, which results in that the working environment of the workers is poor and they cannot hear the unusual sound of the device. According to the inspection, the major source of noise is the vibration of the side plates of the screen frame and bearing. Further, the friction between the supporting base and the transmission gear, sieve, the exciter housing and the damper spring will have a greater noise. Therefore, the noise control requires the use of integrated noise reduction in order to achieve better results. After testing, adding the rubber sheet on the side plate of the sieve box, the feed inlet and the discharge port can effectively suppress the vibration, reducing radiated noise; conducting damping treatment between the inner cover and outer cover can reduce the vibration of the bearing and reduce bearing noise; replacing the steel sieve into the polyurethane sieve with small elastic modulus and low impact noise.
Poor manufacturing precision. The manufacturing plays an important role in the form of the product. Usually, for the success of the product, the good design accounts for 7 percent and the manufacturing accounts for 3 percent. But for the vibrating screen, it has been proved that the manufacturing accounts for at least 5 percent according to the past experience. Among the reasons, the problem of manufacturing materials, manufacturing processes, production equipment is the main reasons that cause the gap between the domestic vibrating screen and the internationally renowned products. This problem can be detailed embodied in the following aspects: the overall geometry of the screen frame is irregular, many defects, rough machining, and welding deformation. This phenomenon is also related to the corporate management which is not in place.

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The Three Effects of the Flotation Machine

Mine flotation machine is the technology equipment that is used to select different kinds of ores, which includes metal, non-metallic, non-ferrous and ferrous metals. The main grading way of the flotation separator is based on the hydrophobicity of different minerals. But its beneficiation process must go through three stages and the three stages have different roles in the flotation process. The following is the brief introduction of the function of the three stages and their influence on the flotation process.
1. Good pneumatic role
As for the ore flotation machine, it must be guaranteed to suck sufficient air into the pulp to generate a large number of appropriate size bubbles. And these bubbles try to be dispersed in the entire tank, the finer the air dispersion is, the better it will be and the distribution of the bubbles will be more uniform, which will provide more and more opportunity for the mineral particles to contact with the air bubbles. The better process performance of this kind of flotation separator is, the higher the flotation efficiency will be. Therefore, the inflatable degree of the mine flotation machine is usually presented by the inflatable volume.
2. Stirring action
Guaranteeing the good stirring action of the ore flotation concentrator is helpful to ensure the ore particles will not precipitate but will be evenly distributed in the tank in suspension, which can make sure that the mineral particles and air bubbles can be in full contact and collision in the tank. At the same time, the stirring action can also promote some insoluble drug to be dissolved and dispersed to facilitate to play the full role of the pharmaceutical and mineral particles.
3. Circulation flow effect
The flotation machine has the function of regulating the pulp surface, the circulation amount of slurry and the inflated amount, which will increase the chance of contact between the mineral particles and bubbles, can maintain the stablity of the foam and has a certain thickness. It not only can remain the purposes mineral, but also can enable the mixed gangue fall off, resulting in a "secondary enrichment". It is capable of continuous operation and easy to adjust. And in the flotation process, it is sometimes necessary to adjust the thickness of the whole foam layer and the slurry flow rate. In the actual production process, from the feeding, the production of concentrate to the discharge of the tailings, all the steps are continuous process and are required the easy adjustment.

The Difference Between Rod Mill And Other Mills

Rod mill, as one of the mills, has its own uniqueness. Compared with the other ball mill equipment, what is the difference between rod grinding mill and them?
As for the rod mill, driven by the reducer and the surrounding large gear through the motor, the cylinder rotates. The cylinder is equipped with the appropriate grinding media - steel bars. Under the role of the centrifugal force and friction, the grinding media is elevated to a certain height is thrown down. The materials to be grinded are conveyed to the interior of the cylinder from the feeding port and then the materials are crushed by the movement of the grinding media. Finally, they will be discharged out of the machine by the force of overflow and continuous feeding to prepare for the next production process. The following is the brief introduction of the differences between rod grinding machine and other ball mill equipment.
1.The general ratio between the length and the diameter of the cylinder is 1.5-2.0 and the inner surface of the end cap should be vertical plane, whose purpose is to prevent the steel bars from and reduce the chaotic motion, bend and break in the cylinder body to ensure the regularity movement of the steel bars. The ratio of length to diameter of the ball mill is small, in most cases the ratio is only slightly greater than 1.
2.It adopts the overflow type and open type to discharge, but not the grid plate. The hollow journal diameter on the discharging end is greater than that of the specifications of ball mill. The operating speed of the cylinder should be lower than that of the ball mill of the same specifications to make the medium within it work in the falling state.
3.Using the steel bars with the diameter of 50-100mm as the ore grinding media, while the ball mill adopts steel balls as grinding media. The length of the steel bar which is made of high-carbon steel with carbon content of 0.8% -1% is shorter than the cylinder. The loading of the bars is approximately 35% -45% of the effective volume.

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The Status Quo of Coal Vibrating Screen

Vibrating screens are a kind of important equipment to help to complete a variety of different industrial processes, which is widely used in coal, chemical industry, metallurgy, ports, water conservancy, electric power industry. In the coal preparation plant and screening plant of coal industry, the screening operations are mainly used in coal preparation and product processing. Vibrating screens have played an important role in the rational utilization of coal resources, protect the environment and create economic benefits for the coal enterprises. Just like some other mining machinery (vibrating feeder,dryer machine), the vibrating screen has a relatively long history. The history of the coal vibrating screen can be traced back to the 1960s, on the basis of absorbing foreign experience and independent innovation, vibrating screen, both in design technology, manufacturing processes, varieties and specifications, and in technical performance and structural strength, has been greatly improved, but there are some inadequacies.
According to the distance from the resonance frequency, the vibrating screen is divided into the the resonance screen and inertial vibrating screen. Currently, in the screening operation of coal industry, the inertial vibrating screen is widely used. Based on the characteristics of the work trajectory of the screen surface, the inertial vibrating screen is divided into circular vibrating screen and linear vibrating screen. Circular vibrating screen is mainly used for the pre-screening and final screening; linear vibrating screen is used for dehydration screening, desliming screening and sculping screening. Circular vibrating screen has more than 40 years of history in coal production, the initially eccentric and simple inertia style are the prim stypes.
Linear vibrating screen is developed on the basis of circular vibrating screen, which is also known as the dual-axis inertial vibrating screen. In the initial stage, driven by the single-motor, the gear is forced to rotate to make the double rollers do the relatively synchronous directional rotation to create the excitation force. In this case, the lubrication and sealing of the geal are easy to have problems, affecting its service life. Therefore, currently , the linear vibrating screen driven by dual-motor without forced drive is widely used.

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