The equipment needed in the calcination process of ammonium paratungstate (APT) mainly includes calciner. According to different designs, calciners can be divided into rotary calcinating furnace, rotary tube calcinating furnace, etc.

Rotary calcinating furnace (rotary calciner) is a kind of equipment for high-temperature heating treatment of powdery or filter materials. It can be divided into coal fired furnace, gas fired furnace, oil fired furnace and electric heating furnace according to the different energy used; It can be divided into direct heating and indirect heating according to heating mode; According to the operation mode, it can be divided into continuous operation and intermittent operation. The calciner is mainly used for reduction, halogenation, sulfation, activation, crystal transformation, oxidation, pyrolysis and other processes, and is widely used in the production process of special materials in inorganic chemical industry, metallurgy, petrochemical industry, construction and other industries.

When the indirect heating continuous operation calciner works, the materials enter the furnace barrel through the furnace head feeder, and the heating furnace is equipped with electric heating elements or fuel burners. The furnace temperature is controlled by the automatic control system to adjust the current of the electric heating elements or the flame of the burner, so that the materials can be baked at a certain temperature. The furnace barrel is horizontal or inclined during operation. The materials are baked in the furnace barrel while moving forward under the rotation of the furnace barrel. The baked materials enter the next process from the discharge end. The roasting time of materials can be controlled by adjusting the revolving speed of the furnace drum or the angle between the furnace drum and the horizontal.

The electric heating calciner takes electricity as its energy source and is mainly composed of the calciner body, electric heating system, insulation furnace, automatic control system, etc. In addition to rotary cylinder calciners, electric heating calciners also have vacuum type, positive pressure type, double cone rotary type and other special calciners for special materials.

Features of electric heating calciner: 1)Good sealing effect and high degree of automation; 2) Automatic control and subsection setting of baking temperature; 3) The heating system is safe and reliable; 4) The surface temperature rise of the insulation furnace is lower than 50 ℃, and the heat loss is small; 5) The equipment is simple and compact in structure, small in volume and light in weight; 6) High efficiency and energy conservation; 7) Low operation intensity, simple maintenance and good operation environment; 8) It is simpler and easier to maintain than the auxiliary equipment of other energy baking furnaces; 9) The operating temperature reaches 400 ℃~1000 ℃.

Gas fired calciner is mainly composed of calciner body, combustion device, heat preservation furnace, ventilation and smoke exhaust device and automatic control system. Combustible gases such as natural gas, water gas and liquefied petroleum gas are used as fuel. They are fully combusted, with high thermal efficiency. At the same time, the combustion process is easy to control, and solid and liquid fuels cause less pollution to the environment.

Characteristics of gas burning calciner: 1) Good sealing effect, reducing material loss and heat loss; 2) Full combustion of gas, high thermal efficiency; 3) Temperature is controlled automatically and section by section; 4) With accidental power failure protection system; 5) Good thermal insulation performance, reducing heat loss; 6) The combustion control system is safe and reliable; 7) The equipment is compact in structure, small in volume and light in weight, and the furnace body can be directly assembled on site; 8) The solid and liquid gas have less pollution to the environment; 9) The operating temperature reaches 400 ℃~900 ℃.