Study on material drying in mineral processing production Henan Hongxing


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Study on material drying in mineral processing

dryer It is the main equipment for dehydration of final product (concentrate) or intermediate product in concentrator. It can further reduce the moisture content of material to meet the requirements of users or the next production process. Mineral processing dryer can dry tungsten, molybdenum, manganese, titanium, iron, copper, lead and zinc, fluorite, kaolin and other metal or non-metallic minerals, which is widely used in mineral processing.

Application of dryer in concentrator

At present, China's concentrators have increasingly strict requirements on the moisture content of concentrate such as anti freezing and packaging. For example, tungsten concentrate is 0.05% - 0.8%, molybdenum concentrate is less than 4%, manganese concentrate is 8% - 9%, titanium concentrate is less than 1%, fluorite concentrate is less than 0.5%, copper concentrate and lead-zinc concentrate are less than 8%. It can be seen that the dehydration of this kind of product is difficult to meet the requirements only by concentration and filtration, and drying and dehydration are needed. The concentrator is located in the northeast of China, so it is necessary to set up a concentrator under - 14 ℃ in winter.


Working principle of dryer

Drying is the use of heat energy to remove part of the material moisture (moisture) of an operation. The commonly used methods are indirect or direct heat transfer drying method, which takes hot gas as the medium and transfers heat indirectly or directly to the wet material, so that the moisture content on the surface of the wet material vaporizes and diffuses to the main body of the air flow through the gas film on the surface; at the same time, due to the result of moisture content gasification on the material surface, the moisture difference between the material interior and the surface occurs, and the moisture content inside the material is in the gaseous state So as to obtain the form of a liquid or dried material.

Necessary conditions for drying materials

Material drying The necessary condition is that the vapor pressure on the material surface (i.e. the vaporization intensity) must be greater than the partial pressure of water vapor in the drying medium. The higher the evaporation rate of the two media, the faster the drying pressure. If the pressure difference is zero, the drying operation will stop. It can be seen that drying is a process combining heat transfer and vaporization intensity.

Drying mode of dryer

There are two ways to dry the material directly through the wet wall, that is, to dry the material directly through the gas without contacting the gas. The direct drying process is a process of heat transfer and moisture removal at the same time, that is, the high-temperature gas is used as the heat carrier to directly contact with the material, transfer the heat to the wet material, and take away the water vaporized from the material at the same time. The indirect drying process is a process of drying by heating the container with hot gas to vaporize the moisture in the container.

Study on drying process of material in dryer

When the material is directly dried with high temperature gas (air or flue gas), the process is relatively complex. However, this process can be studied from two aspects: the flow of moisture in the material and the external conditions (temperature, humidity and flow rate of gas, contact between material and gas, shape and particle size of material, etc.). The moisture in loose materials is composed of unbound water or bound water. Unbound water is a kind of water existing in the material in free state, that is, the surface wetting moisture and pore water (capillary water), which is easy to remove. The combined water is the absorbed water in the material, i.e. crystal water, which is difficult to remove.

Any material can only be dried until the balance of moisture. Equilibrium moisture refers to the moisture content of the material when the vapor pressure on the material surface reaches equilibrium with the vapor partial pressure in the surrounding air. According to the change of drying speed, the drying process can be divided into four stages: preheating stage, constant speed stage, decreasing speed stage and the equilibrium stage when the moisture content of the material has reached a certain condition, that is, the stage when the moisture content in the material is balanced with the air humidity.

At present, the domestic dryer Market is not completely transparent drying equipment From the appearance, it is almost the same, but the equipment is very different, the cost of use is unpredictable. In order to protect the rights and interests of consumers, please visit our customers Henan Red Star Call the official website at 266771 or take a shortcut online.

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