Relationship between Feeding Density and Overflow Granularity

The classifier combines with ore grinding machine to form closed working line. Before the grinded materials entering into the classifier, certain amount of water should be added by the constant pressured pool to make sure the density of ore is suitable. In the actual operational process, fix the density of feeding ore, the overflow concentration will also be unchanged, and the granularity of classified materials will be less variable. Therefore, control the feeding density of ore has become an effective means to control the overflow granularity. In practice, based on the requirements of ore beneficiation on the density, the feeding density of classifiers is always much higher than the critical density. At this time, if add more water, the overflow granularity will be finer, and the subsiding grit amount will also be increased correspondingly.
However, after all, the classifier itself cannot manufacture fine grade. With the increasing of the amount of circulatory returning sand, more ore will be added into the classifier. The feeding density increases accordingly, and the overflow granularity becomes course. Ultimately, the separating granularity is decided by the producing amount of fine granularity produced by grinding machine. The overflow products are the final products of ore grinding. The function of classifiers is to separate qualified granularity timely to decrease over grinding, and to supply suitable high-density returning sand to ore miller to improve the grinding efficiency. The classifier functions well, the ability of ore miller can be fully used, and as a result, the overflow granularity could be decreased. Therefore, the selection of working conditions of mechanical classifier should depend on the requirements of ore separating line and service provided to grinding machine.
In order to improve the separating efficiency, the coarse mechanical classifier could be replaced by screening equipment, while in fine separating process, water driven screw classifier could be used. The transferring parts of single spiral separator consist of the motor, a pair of leather wheels, speed reducer and spur gear auxiliary.

The Developing State of Domestic Roller Crusher

In terms of the adaptability, the function of the domestic double roll crusher is relatively simple, and its adapting range is much narrow. There are stringent regulations on the shape and volume of the roll crusher, which are generally applied only to one or two kinds of crushers. The specifications of roller crusher produced by the same manufacture are different in China, either is the productive volume, which brings a certain difficulty to the relative works. However, the foreign crushers manufacturers attach great importance to this problem, so the roller crushers produced by them are much more flexible and adaptable.
The roller crusher has the advantages of reasonable structure, well-made production, high productive volume, low energy consumption, convenient operation, less over powder crushing and breaking wet or viscous materials. The double roll crusher is suitable for crushing all kinds of materials with medium or low hardness, and its compressive strength is generally less 700kg/cm2. The production capacity, heavy weight and low ability to crush large-sized materials make it unsuitable for the roll crusher to crusher hard materials. But in the chemical industry, coal and coking industry, they are strict with the size and shape of crushed products and over crushed phenomenon, therefore the roll crusher must be chosen. The machine should be installed horizontally on a concrete foundation and anchored firmly. In order to reduce vibration and noise, it’s better to put hard wood or other cushioning materials on the foundation of concrete.
As for the quality, roll crusher is a more complex mechanical machinery, which covers the mechanical, electrical, gas, light and other technologies. Currently, the initially designed roll crusher and the later installing technology produced by the domestic manufacturer all have a great distance with that of the foreign manufactures for the development of more than ten years. The running speed of domestic crushers is staying mostly in the middle and low level with ordinary automated degree, so the producing efficiency is much lower than the foreign counterparts, which increase the cost of enterprises intangibly, decrease the benefits and lead to great waste. All in all, the current domestic crusher has the disadvantages of single adaptable materials, small changing range of the size of carton and medium and low speed level of imperfections.

The Comparison between the Domestic and Abroad Crushers

Traditional jaw crusher is widely used in industries because of its simple structure, reliable operation, easy manufacture, convenient maintenance, low price and high adaptability, but its disadvantages are discontinuous crushing, relatively low efficiency, small crushing ratio, uneven wearing of jaw plate caused by uneven feeding.
The overwhelming majority of manufacturers and working sites are still using traditional single toggle jaw crusher. The technical level of jaw crushers manufactured by domestic manufacturers is very different from each other, and there are a small number of manufacturers whose products are close to the world advanced level, while most of the manufacturers have a larger gap with the world advanced level. The weight of domestic jaw crusher is generally heavier than that of abroad crushers in the same specification. The rack of jaw crushers takes a large weight (casting rack takes 50%, welding rack takes 30%). The rack of foreign jaw crushers is all welded, even the mobile jaw is welded. In addition, the cast is a high energy consuming process, so from the perspective of energy conservation, welded frame should be vigorously developed.
Using welded rack for jaw crushers is the long-term development of the right direction. In addition, the unreasonable structural design of the rack is also an important reason to increase the weight of the machine. The rack-structure design should first be based on the force, under the conditions to meet the requirements of strength, stiffness, and reduction of weight. Under normal circumstances, the crusher is not need to be added the longitudinal ribs.
In a summary, to improve the backward situation of domestic jaw crusher, comprehensively improve the technical level of the jaw crusher to catch up with the world advanced level, and create the world brand jaw crusher is a priority. The fundamental factors to ensure the best performance of the jaw crusher are optimum motion characteristics of moving jaw. This feature is obtained by agencies optimal design. Therefore, the jaw crusher organizations optimize the design to ensure the best performance of the fundamental crusher.

The Continuous Development of Compressive Crushing Equipment

With the continuous development of industries like roads, bridges and construction, particles are used more and more widely. The compressive crushing equipment is the most widely used equipment in materials crushing. In terms of cone crusher, the emphasis is how to improve the producing efficiency, decrease the energy consumption, and expand the service life. The compressive force of crushers influences the performance of the crushing equipment, so the research on the crushing force has great influence on the analysis of dynamics and the prediction of service life.
Based on the material compression experiments and the experimental data analysis, the existing method of compressive force calculation and its deficiency are analyzes, and a solution model of compressive force is built. It provides the basis of precise compressive force action for dynamic performance analysis of the complete machine and cavity optimization design. Based on the laminated broken working theory of rock cone crusher, the bulk material movement in crushing cavity and cavity layering situation is analyzed and the key influencing factors of compressive force is discussed. With mechanics experimental study of compression processes of three kinds of rock materials using RMT-150B Rock mechanics test system, it gives a regression analysis on experimental data, builds three factors mathematical model of compressive force, and solves compressive loads distribution in details based on material layering situation.
Different crushers have different specifications and different use scope. Currently, course crushing always chooses jaw crusher or rotary cone crusher; medium crushing uses standard cone crushers; fine crushing uses short-head China cone crusher; course grinding used rod mill, and fine grinding uses ball mill. According to the way of crushing and the mechanical structure, crushing equipments could be divided into six categories: Jaw crusher(also named the mouth of tiger), Cone crusher, Roll crusher, Impact crusher, ore-grinding machine, and other crusher, like disk crusher, vibrating crusher, etc.

The Improvement of the Level of China's Iron Ore Beneficiation

Flotation is a kind of important mineral processing technology. In the world, Billion ore and materials be processed by using flotation separator every year. It is used widely in various metal minerals and non-metal minerals processing. In addition it can be used in chemical industry, agriculture, food, medicine, environment protection, etc. There are a lot of factor can influence the result of ore flotation equipment. Such as ore property, mog, flotation consistency, flotation reagents addition, flotation cell level, flotation aeration rate, etc. In addition ore property, mog, flotation consistency, flotation reagents addition are Controllable parameters. The traditional manual control can’t make the parameters at their best. So achieving the flotation automatic control makes important sense.
In the first, the current situation of flotation control at home and aboard is introduced. According to the situation of DAHONGSHAN copper mine, the flotation control system are consist of flotation tank level control system, flow rate control system, flotation reagents addition control system. Flotation tank level control system can get an offset value by compare the detection level value with level setting value. Control the pneumatic actuator with offset value to make the flotation tank level at setting value. Flow rate control system can get an offset value by compare the detection flow rate value with flow rate setting value. Control the clampvalves with offset value to make the flow rate at setting value. Flotation reagents addition control system The Mitsubishi PLC is used as controller, and use flow meter and concentration meter collection to get density and flow of ore.
In recent years, raising the level of China's iron ore beneficiation process is a new mineral processing equipment and the support of foreign advanced equipment, especially in recent years in the crushing, grinding and classification, sorting (including re-election, magnetic separation, flotation, etc.), dehydration, filtration and other aspects of the development or introduction of many new and efficient equipment, and has been successfully applied to provide device protection for beneficiation technology progress.

The Construction and Characteristics of Ball Mills

There are many kinds of ball mills, but most ball mills have the same installing ways and procedures. Because the violent vibration of ball mills during operation, we suggest the ball mill should be installed on the steel concrete whose weight is 2.5-3 times heavier than itself to make sure the stable operation of the ball mill, and the reduction on the damage to the buildings. This steel concrete foundation should be fixed on the ground, away from the building for at least forty to fifty millimeters, which can decrease the damage to the building to its minimum.
Ball mills are the very important grinding equipment in the process of ore beneficiation. The grinding operation of ball mill is a mechanical process, and this depends on two factors: the first one is the mechanical strength of these rock and ore, and the second one is the state of application of force of the grinding machines. The feeding materials enter into the first grinding cylinder evenly through the hollow spiral bearings. Within this cylinder, there are stepped lining plates or waving plates and steel balls in different specifications. The centrifugal force takes those balls to a certain height and the balls will fall down because of gravity, so strong impacting and grinding force will be produced. After the course grinding on the first cylinder, materials will have further grinding in the second cylinder. The grinding will finish when the powder has been discharged from the discharging bucket.
This grinding machine consists of feeding part, discharging part, rotary part, transferring part etc. The inner hollow bearings are made of steel, and the inner plate is changeable. The rotary big gear is cast with hobbings and the drum is equipped with wear-resistant liner. This machine operates stably and reliably. According to the differences in types of materials and discharging ways, we can choose from dry ball mills and wet trellis ball mills.

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The Drying Method of Cement Industry

  In the cement plant, when people take dry production, a variety of aqueous materials, such as raw materials, coal and mixed material are required for drying, and for the wet production, coal, and the mixing materials also need to be dried, so as to ensure normal powder grinding operations. The moisture content of the grinding material has a great impact in the quality of the materials and mill grinding operation. If more water into the grinding materials, grinding will contain high moisture content, so the fine material will adhere to the grinding body, lining and compartment panel, so that the grinding efficiency will be decreased. What’s more, too high moisture of grinding material will inevitably make the operating conditions of the mill deteriorate, and make the operation and quality control difficult. In addition, mixture ratio changes along with the moisture of feed mill materials, thus the grinding quality of the products also will be affected.
  Excluding the moisture of material is the essential part in the cement production. Cement plant uses drying equipments to dry materials independently, and those equipments include rotary dryer, suspension dryer, the flow pattern dryer, boiling dryer, gravity dryer, and so on. One of the most commonly used is the rotary dryer. This dryer’s drying efficiency is low with a high investment, but it has a high adaptability of the material. A variety of materials can be dried by it, and the equipment is simple and reliable, so it gets widely used.
  The drying of the material can be natural or artificial. Natural drying is to stack the wet materials in a shed or outdoor sun field to make it dry by sun and wind. The advantage of this method are no special equipment, no fuel consumption, but slow drying, low yields, high labor strength, serious operating conditions, and the impact of climate are the limitations of this method. Artificial drying is to stack the material in a specialized dryer. The artificial drying has many ways to pass heat to the material, such as the use of hot air or hot flue gas, the convective heat transfer; the use of an infrared lamp or hot metal, ceramic, refractory materials and heat transfer. Heating and drying method using hot air or hot flue gas convection is called convection drying. The hot air or hot flue gas is known as the drying medium. In accordance with the characteristics of the cement industry materials, people commonly use convection drying method. The heat source is easy to obtain, the device is relatively simple, and the total cost is also low. When drying materials, hot air or hot flue gas heat to the material, so that it evaporates and, at the same time rely on ventilation equipment, drying medium and drying equipment constantly update to exclude water vapor.

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The Specific Introductions of the Functions of Dryer

  Dryers can be divided into three types, including indirect heat transferring dryer, compound heat transferring dryer and direct heat transferring rotary dryer. Materials are heated directly or indirectly during their movement in the dryer machine, and then they will be discharged by belt conveyor or spiral conveyor after being dried. Rotary dryer is generally used to dry particles, but sometime it can also dry materials with much higher moisture under the condition of adding some dry materials.
Dryers can not only dry materials, they also have other functions.
1, the dryer is an inclined rotary cylinder
  Raw materials are added from the high-end of the cylinder. With the continuous rotary movement of sand dryer, material gradually moves from high-end to low-end, so sand dryer is a transferring equipment.
2, the dryer is a burning equipment
  The milled coal powder is blown into the sand dryer by pulverized blower. Energy produced by burning is transferred to materials in the way of radiation, convection and conduction. As fuel combustion equipment, sand dryer has a broader space and thermodynamic field, which can provide adequate air to install excellent combustion apparatus, and to ensure full combustion of fuel, and to provide the necessary heat for the calcining of clinker.
3, the dryer having a heat exchange function
  The sand dryer, having a relatively uniform temperature Session, formed cement clinker to meet the requirements of the various stages of the process of heat exchangers.
4, degradable waste function
  The sand dryer has a high temperature special and long-time thermal field of airflow stagnant, biodegradable chemical, pharmaceutical and other industries discharge of toxic and hazardous waste. At the same time, most of the heavy metals in cured to form a stable salt, avoid secondary pollution of the waste incinerator prone in the clinker.
5 , the dryer has a chemical reaction
  A series of physical and chemical reaction happen in the process of drying clinker. Clinker rotary dryer can meet different mineral phases formed on the heat and the temperature requirements, but also to meet their requirements on time, which is ideal for the chemical reaction devices.
 

Searching for Ways to Optimize the Operation of Jaw Crushers

The crushing of materials is widely used in metallurgical, mining, building materials, chemical, electric power industry and so on. There are a large number of raw materials and reuse of waste treatment needed to be crushed every year. In the primary crushing stage, jaw crusher is the application of the main equipment. The performance of jaw crusher elated to the level of productivity and product quality levels, and developed energy efficient crusher can save a lot of costs and improve production efficiency. It is important to achieve high-quality, high yield, low cost, and low power consumption.
  Let’s take jaw crusher of PE250×400 as an example, based on computer graphics and virtual prototyping technology, optimization of working device with a capacity target, combination of experimental and simulation analysis of the breakage force. The paper established three-dimensional model of jaw crusher by Using Solid Edge software, and simplified the working device, based on virtual prototyping technology, exerted constraints on working device by ADAMS software, got the speed, acceleration, angular velocity, angular acceleration of the center of gravity of the moving jaw, and analyzed the rate of size on the performance of crusher. Based on the results of simulation, it got the trace and the trip value of moving liner, and it will provide reference for future design. We established the parameter model for working device in the ADAMS software, and established the capacity as the objective function, the length of crank and the link as the design variables, and built the relationship of the design variables, through the design study, it analyzed the crank length and link length impact on the capacity. By using optimal design, it gets the optimal value when the capacity is the maximum value.
  Finally, the breakage force was analyzed by using the combination of experimental and simulation methods. The conglomerate and siliceous rocks are used as the research object. After setting the test program, it got the maximum failure load of the conglomerate and siliceous rocks and their performance parameters by using uniaxial compression test. Through simulation it got the impact force of the inlet, middle, and the outlet of crushing chamber. This kind of research has provided an important basis for computing the maximum crushing force.sand washer : http://www.hxjq-crushers.com/8.htm
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