Selection and Maintenance Technology of Light Burned Magnesium Powder

It is widely used in hazardous waste disposal industry in China. The quality of refractories in rotary kiln affects the stable operation of rotary kiln. The selection and maintenance of refractories for hazardous waste treatment rotary kiln are analyzed for reference in engineering application. Hazardous wastes have corrosive, toxic, flammable, reactive and infectious characteristics according to the definition of the National Hazardous Waste List. Hazardous waste management is required, which may have harmful effects on the environment or human health. Thermal treatment (incineration) of hazardous wastes can not only completely eliminate the toxicity and harmfulness of wastes, but also minimize the volume of hazardous wastes, which is the most powerful means of harmless waste reduction. At present, most of the newly built hazardous waste incineration and disposal projects in China give priority to rotary kiln as the type of hazardous waste disposal furnace, which can effectively deal with hazardous wastes of different shapes and phases.

Rotary kiln incinerator, also known as rotary kiln, is a slightly inclined steel hollow cylinder lined with refractory bricks. Most waste materials are heated by the gas generated during combustion and the heat transferred from the kiln wall. Solid waste is incinerated from the front end to the kiln to rotate to achieve the purpose of stirring waste. It is necessary to keep a proper tilt when rotating in order to facilitate the decline of solid waste. In addition, waste liquor and gas can be fed from kiln head or secondary combustion chamber, and even whole barrel waste can be fed into rotary kiln incinerator for combustion.

Rotary kiln incineration technology is the most mainstream technology in hazardous waste incineration technology. It is the most widely used type of furnace. Light burning magnesia powder is a kind of multi-purpose incinerator with strong adaptability. It can incinerate various solid, semi-solid, liquid and gas wastes, and the combustibility of various types and shapes (granules, powders, lumps and barrels) Waste can be sent to rotary kiln for incineration.

Hazardous waste incineration in rotary kiln usually goes through several stages, such as drying, pyrolysis, combustion and burnout. After these stages, the harmful components in hazardous waste are fully decomposed and destroyed under the action of high temperature, forming high temperature flue gas and slag. These high temperature flue gas and slag will cause corrosive damage to refractories built in rotary kiln.

(1) High temperature resistance. It can operate in high temperature environment above 800 C for a long time.

(2) High strength and excellent wear resistance. Refractories in rotary kilns need to have a certain mechanical strength to withstand the expansion stress at high temperature and the stress formed by the deformation of rotary kiln shell.

(3) Good chemical and thermal stability to resist the corrosion of chemical substances in flue gas and to withstand the alternating thermal stress under incineration.

(4) The stability of thermal expansion is good. Although the thermal expansion coefficient of the shell of rotary kiln is larger than that of the refractory of rotary kiln, the temperature of the shell is generally about 150-300 C, and the temperature of the refractory is generally above 800 C, which may cause the thermal expansion of the refractory to be larger than that of the shell of rotary kiln and easy to fall off.

(5) Porosity is lower. High porosity will make the smoke easily penetrate into refractories and corrode the refractory body.