Selection and maintenance technology of light burned magnesium powder

It is widely used in domestic hazardous waste disposal industry. The quality of refractory materials in rotary kiln affects the stable operation of rotary kiln. The selection and maintenance of refractory materials for hazardous waste treatment rotary kiln are analyzed, which can be used as a reference for specific engineering application. According to the definition of the national list of hazardous wastes, hazardous wastes have corrosive, toxic, flammable, reactive, infectious and other hazardous characteristics. It may cause harmful effects on the environment or human health and needs to be managed as hazardous waste. Among them, the heat treatment (incineration) disposal method of hazardous waste can not only completely eliminate the toxicity and harmfulness of waste, but also reduce the volume of hazardous waste to the greatest extent. It is the most powerful means for harmless and reduction of waste. At present, most of the newly-built hazardous waste incineration disposal projects in China give priority to the rotary kiln as the type of hazardous waste treatment furnace, which can effectively treat hazardous wastes with different shapes and phases.

Rotary kiln incinerator, also known as rotary kiln, is a slightly inclined steel hollow cylinder lined with fire-resistant bricks. Most waste materials are heated by the gas generated in the combustion process and the heat transmitted by the kiln wall. Solid waste is sent to the kiln from the front end for incineration to achieve the purpose of mixing waste by rotation. Proper inclination must be maintained during rotation to facilitate the sliding of solid waste. In addition, waste liquid and waste gas can be sent from the kiln head or secondary combustion chamber, and even the whole barrel of waste can be sent to the rotary kiln incinerator for combustion.

Light burned magnesia powder

Rotary kiln incineration technology is the most mainstream technology in the current hazardous waste incineration technology and the most widely used furnace type. Light burned magnesium powder is a multi-purpose incinerator with strong adaptability and can incinerate a variety of solid, semi-solid, liquid and gas wastes. Combustible wastes of different types and shapes (particle, powder, block and barrel) can be sent to rotary kiln for incineration.

The incineration of hazardous waste in rotary kiln generally 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 to form high-temperature flue gas and slag. These high-temperature flue gas and slag will cause corrosive damage to the refractory built in the rotary kiln.

(1) High temperature resistance. It can operate at high temperature above 800 ℃ for a long time.

(2) High strength and excellent wear resistance. The refractory materials in the rotary kiln need to have certain mechanical strength to bear the expansion stress at high temperature and the stress formed by the deformation of the rotary kiln shell.

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

(4) Good thermal expansion stability. Although the thermal expansion coefficient of the shell of the rotary kiln is greater than that of the refractory of the rotary kiln, the shell temperature is generally about 150 ~ 300 ℃, and the temperature borne by the refractory is generally more than 800 ℃, which may lead to greater thermal expansion of the refractory than that of the shell of the rotary kiln and easy to fall off.

(5) The porosity should be low. High porosity will make the flue gas easy to penetrate into the refractory and corrode the refractory body.