Coal Washing Machine: What Is Coal Washing?

 Today, coal supplies a third of all energy used worldwide and makes up 38% of electricity generation. In addition, industries such as iron & steel, cement, fertilizers, and pulp & paper rely on coal for their processes and energy requirements. Given the position of coal in the global energy framework and the legitimate environmental concerns related to it, the production of clean coal technologies is essential to accomplish both efficient energy production and a reduced environmental footprint. This is where coal washing comes in.

 

Depending on its quality, coal needs to be “washed” with water and chemicals to remove sulfur and impurities before it can be burned in a power plant. Coal washing, or coal beneficiation, is widely seen as an efficient method for getting the most from run-of-mine coal. On the other hand, it is a water-intensive process: typically, washing one ton of coal consumes about 45 m3 liters of water. As environmental regulations tighten, mechanized mining increases impurities in run-of-mine coal and production rates continue to surge, there is a constant need for improving coal quality.

 

A coal preparation plant is a facility that washes coal of soil and rock, crushes it into graded size chunks and stockpiles grades, preparing it for transport to market. Coal washing represents the most important step of coal preparation. The raw run-of-mine coal requires selective qualitative and quantitative analysis for finding the most suitable operating conditions for cleaning coal to obtain the desired quality. Among these analyses, the washability test is most important.

 

Coal that comes from a mine is a complex mixture of materials with a large variety of physical properties. In addition to the coal itself, pieces of rock, sand and various materials are contained in the mixture. Thus, before coal can be sold to consumers, it must be cleaned. Coal washing involves using water and mechanical techniques and relies on gravity and the difference of density between coal and its’ impurities, which are usually more densely packed due to the fact that they are inorganic. Washing coal increases its efficiency and quality, therefore increasing its price. Coal washing can also help to reduce emissions from burning.

 

The washability characteristics of a coal reserve are provided by obtaining liberation data on the raw coal sample. Liberation refers to the amount of physical breakage required to separate material of different material densities. Low density material is clean coal while high density material is reject rock.

 

Coal washing is accomplished by one of two major processes, by density separation or by froth flotation. Both processes depend on the fact that the particles of which a coal sample are made have different densities. When water is added to the sample, particles sink to various depths depending on their densities. The various components of the sample can be separated from each other. A number of devices and systems have been developed for extracting the various components of coal once they have been separated with a water treatment. One of these devices is the jig. In a jig, the column of water is maintained in a constant up-and-down movement by means of a flow of air. Clean coal particles are carried to the top of the jig by this motion, while heavier refuse particles sink to the bottom.

 

In the coal washing process, the washability characteristics of coal are applied:

• To find the relative ease for separation of coal from the refuse.

• To find the effectiveness of coal washing.

• To characterize the type and amount of impurities.

• To gather the information for designing a separation plant.

The washability test is done by float and sink method. It is an important analytical technique for the cleaning of coal in the most effective way.

 

What is Coal Preparation Plant

A coal preparation plant is a coal processing plant that includes a series of processes: raw coal screening, squashing, coal washing, separation, tidy coal dewatering as well as sludge recycling. Which can separate coal from contaminations, remove mineral impurities from raw coal and divide it into different specs of products.

The primary products of the coal prep work plant are clean coal, lump coal, and by-products such as tool coal and slime. Usually, coal prep work plants are separated right into:

Coking Coal Preparation Plant: It generates reduced clean ash coal for coking.

Vapor Coal Preparation Plant: It produces fuel to coal for thermal power generation, heavy steam locomotives, boilers, and also raw coal for the chemical industry.

 

Why is Coal Preparation Need

Raw coal is blended with numerous mineral pollutants in the formation process and inevitably mixed with rocks and other pollutants in the roofing system and flooring in the process of mining and transport. So the raw coal must be prepared, the primary function of coal prep work can be summed up as adheres to:

( 1) Get rid of impurities in run-of-mine coal, decrease ash and also sulfur, improve high coal quality and fulfill the requirements of users;

( 2) Separate coal right into different top quality and specs to meet the requirements of individuals, so regarding make effective as well as a sensible use of coal and also save cost;

( 3) After coal cleaning, gangue can be discarded right away, which can decrease void transportation as well as create conditions for extensive use of gangue;

( 4) Coal cleaning can eliminate a lot of the ash and 50%-- 70% pyrite sulfur and decrease the air pollution caused by coal burning. It is the property of clean coal technology.

 

Just How Coal Dewatering Screen Work

The coal dewatering screen takes on double electric motor self-synchronization technology, general eccentric block, and flexible amplitude vibration exciter.

 

The coal dewatering screen is primarily composed of a screen box, vibratory exciter, support group, and motor. When working, both unconnected actuators are driven by belt combinings to run synchronously and also backward. The centrifugal pressures produced by the two teams of eccentric blocks are superimposed along the vibration direction and neutralized by reverse centrifugation, forming a single fired-up vibration along with the vibration instructions, which makes the screen box move back as well as forth in a straight line.

 

The sludge going into the coal dewatering screen changes the surface area water stress through the exciting pressure. The slurry water travels through the screen to become the material under the screen. In contrast, the screen panel blocks the fine material to create a filter layer to progress and discharge intoxicated of vibration pressure.

 

Coal Dewatering Screen Applications

Coal dewatering screen has a variety of exceptional properties and functions of average dewatering screen and accepts thickeners for dry discharge of tailings, which is the best equipment for dewatering and dry discharge of tailings presently. A coal dewatering screen is generally used to classify the tool and refined materials, with a large processing capacity and high screening efficiency.

 

How To Improve The Coal Washing Process

In the process of coal washing, improving coal washing process can ensure that coal washing can reduce the pollution caused to the environment as well as reduce the cost in the process of coal washing.

 

1.Improve coal washing methods

Nowadays, the coal washing methods are different because the coal types are different among coal mines. In the process of coal washing, it is necessary to ensure that coal washing does not cause pollution to the environment and also to reduce the cost of the coal washing process. In the process of coal washing, the coal washing method should be improved and optimized. Although the way of washing coal differs from one coal mine to another, the remaining impurities after washing coal should be effectively used in other aspects. For example, in the process of coal washing, some gangue can be used as construction materials. This can not only reduce the waste of resources, but also enhance environmental protection. Some dry washing processes in the coal washing process can be widely used to ensure better combustion of coal carbon. The chemical way of coal washing can also ensure the reuse of water and effectively reduce environmental pollution and resource waste.

 

2.Strengthen the management of coal washing equipment

Generally, coal mining enterprises will leave the management of coal washing equipment to professional staff in the process of setting up coal washing equipment. If environmental pollution is caused in the process of coal washing, it is necessary to check the spacing between equipment, rotational speed and other parts in time. Coal mining enterprises should organize professional staff for training, to let specialized staff master reasonable operation methods, and to have certain standards for the control of water consumption of coal washing. To ensure that the device as a whole is always under the unified standard in the application process. The management of coal washing equipment is to better ensure the normal work of coal washing equipment and will not affect the coal washing process.

 

3.Control the cost of coal washing

The process of coal washing should continuously reduce the cost, and the application of coal automation should be improved. Improve the management and control system of electromechanical equipment to reduce the existing problems. At the same time, strengthen the control for the whole coal washing process, and reduce unnecessary maintenance costs in the process of coal washing. Start from raw materials to continuously improve the process of coal washing and reduce the waste of raw materials. Effectively ensure the virtuous cycle of the whole production in the process of coal washing, and ensure the development of the ecological chain of coal industry.

 

Fengwang specializes in providing coal washing equipment, please feel free to contact us if you need them.