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.

http://ballmillmachine.blogspot.com/

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.

Combination crusher :  http://www.china-crusher.com/combination-crusher1.html
Raymond mill :  http://www.ore-machine.com/raymond-mill.html

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
vibrating screen : http://www.ore-mills.com/vibrating-screen.html

Steel Balls in the Ball Mill

The kinetic energy of steel ball plays an important role in the ball mill. No matter what kind of movement the steel ball do, the kinetic energy of moving steel ball is always changing. Now, let’s analyze the change of kinetic energy in a cycle of movement.

The mechanical energy of steel ball is zero, when it stays motionless at the throat of ball mill. When the ball mill raises the steel ball up depending on the friction with cylinder, the ball starts to move, and has kinetic energy. In this process, the grid power is transferred into the mechanical energy of the ball mill. This mechanical energy will be passed to steel ball through the movement. When the cylinder of Ball Mill brought the ball to the highest position, the ball will get the maximum gravitational energy. Simultaneously, the steel balls still have the initial kinetic energy. When the steel balls fall or slip down from the highest position, the gravitational potential energy begins to decrease, and the kinetic energy begins to increase. In this process, the mechanical energy of steel balls is transferred into kinetic energy. Before the moment the steel ball falls against ore block, the mechanical energy of the steel ball is completely converted to kinetic energy. The kinetic energy released by the striking force acts Nugget. In this process, the steel balls deform, crack and expand the capacity as well as the formation of new surface. So far is the end of a movement cycle of the steel balls. The steel balls will be in the lowest position of the cylinder, and gravitational potential energy is zero. Then, they will be taken up again by the cylinder to start the second cycle of movement. They will repeat the cycle again and again.

We can see from the change of energy of steel balls in a cycle that from the physical point of view, steel balls are the carrier of crushing effect, which are used to impact and break the ore; in terms of the transference of energy, the steel ball is the medium of energy transferring. Steel balls transfer the mechanical energy of cylinder into their own energy, and then transfer to ore by crushing and impacting. So, the reason why we say steel balls are the medium of grinding ore is that they are the medium to transfer the energy and crush ore.

Materials Influence the Efficiency of Vibrating Screen

Enrichment phenomenon always happens in the production process of vibrating screen, that is to say, the screening mesh is blocked, the effective screening area becomes smaller, or the working efficiency becomes lower. Those are mainly caused by the type and size of feeding materials, the density, particle size, and particle composition of materials.

(1) The physical properties of materials will be different if the type of materials and particulate material are different, The types of materials can be divided into two categories : brittle and viscous. Viscous material is easy to form material's dense adhesions to plug the screen in the process of screen, so that the permeability decreased. But brittle materials are on the contrary, and the efficiency of the process can be guaranteed. The particle shape of the material will also affect its permeability screening rate. The cubic shape and the ball-shaped materials are easy to go through the screen, while the sheet material is easily stuck in the mesh so that the screening efficiency of the process is reduced.

(2) Material particles are substantially in accordance with the stratified and permeable sieve of the size of the particle volume, i.e. the bulk density of the material directly affects the vibration sieve processing capability. Bulk density bulk materials go easily through the sieve, so the screening efficiency is also higher; on the contrary, it is not easy to loosen less dense materials and powder materials through the sieve screening, so the efficiency is low.

(3) Material moisture content is too high, so they are easy to adhere during vibration. Physical block pressed against each other adhesions group to increase the resistance of the material movement, so that the material particles layered with transparent screen difficulties; materials adhesions also make smaller mesh size, clogged sieve, reducing the effective screening area, sometimes even unable to carry out the screening. Therefore, when the material moisture content is too high, the screening process should consider some remedies, such as to take such measures like drying material.

 (4) The vibrating frequency is influenced by many factors in the process of screen. The most direct and most important factor is the relative size between granularity and sieve mesh. The ratio of material particle size and the mesh size is called the relative granularity. The smaller the relative particle size, the higher the probability of the materials to go through the screen. When the relative particle size is close to 1, the probability of through the screen approaches to zero. Usually relative material particle size equal to 0.7-1.0 called difficult materials or critical materials. Difficult sieve materials also affect the probability of material ingredients through the sieve. The greater the content of the material in difficult materials through the sieve, smaller the probability, so screening efficiency will be lower. In order to be able to get a higher screening efficiency, we should try to reduce the content of material in difficult materials. In addition, the particle size index differences have a certain impact on the screening efficiency. When the particle index difference is too large, it will result in the production cycle. Therefore, the aggregate gradation should be strictly controlled.

If Something Wrong Happened to Jaw Crusher

We check and maintain our machines every day according to the instructions, but there still might be something wrong happened to those machines. Let’s talk about some commonly seen problems of jaw crushers and analyze how to solve them.

   If the main engine stops working suddenly, there are five possibilities. 1) The discharging port is blocked, as a result, materials are all blocked within the crusher. 2) The triangle belt driving geneva wheel looses, and belt slips. 3) The fastening equipments of eccentric shaft loose, so there is no space on the sides of bearing. The eccentric shaft is blocked and cannot rotate. 4) The voltage is too weak, so that the main engine cannot break down the large materials. 5) The bearing is broken. Accordingly, the methods we should take are 1) clearing discharging port to ensure smooth material; 2) tightening or replacing the triangle belt; 3) re-installing or replacing the adapter sleeve; 4) adjusting the voltage of the workplace to make it comply with the voltage requirements of main engine; 5) replacing the bearings.

  If the crusher stops breaking materials, but the genava wheel of the main engine and mobile jaw still work, the reason might be the breakage of stretched spring and draw bar, or the drop or breakage of bracket. The ways to solve the problems accordingly are replacing the spring, draw bar, or bracket.

If the adjusting seat breaks, the reasons could be that bracket and bracket pad are bought or restructured by themselves, which does not meet the requirements of OEMs design; mounting bolts adjusting the seat loose; adjusting seat has serious casting defects or welding defects. The remedy methods are replacing the adjusting seat with OEM original bracket and bracket pad; replacing the adjusting seat and fastening the bolts; replacing the adjusting seat.

If the spring breaks, the reason is users didn’t loosen the spring when they adjust the discharging port small. The only resolution is to change another spring.