Selection and Maintenance Technology of Light burned Magnesium Powder

It is widely used in domestic hazardous waste disposal industry. The quality of refractory materials of rotary kiln affects the stability of rotary kiln. The selection and maintenance of refractory materials for rotary kilns for hazardous waste treatment are analyzed for reference in specific projects.

Hazardous waste has corrosive, toxic, flammable, reactive, infectious and other hazardous characteristics according to the definition of National Catalogue of Hazardous Wastes. It may cause harmful effects on the environment or human health and needs to be managed as hazardous waste. Among them, thermal treatment (incineration) and disposal of hazardous waste can not only completely eliminate the toxicity and harmfulness of waste, but also greatly reduce the volume of hazardous waste, which is a 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 kilns as hazardous waste treatment furnaces, which can effectively treat 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 in the combustion process and the heat transmitted by the kiln wall. Solid waste is sent into the kiln from the front end for incineration to achieve the purpose of mixing waste by rotating. During rotation, proper inclination shall be maintained to facilitate the sliding of solid waste. In addition, waste liquid and waste gas can be sent from the kiln head or the secondary combustion chamber, and even the whole barrel of waste can be sent to the rotary kiln incinerator for combustion.

Rotary kiln incineration technology is the mainstream technology in the current hazardous waste incineration technology. It is a furnace type with more than Z applications. Light burned magnesium powder is a versatile incinerator with strong adaptability, which can incinerate a variety of solid, semi-solid, liquid and gas wastes. All kinds of combustible wastes of different types and shapes (granular, powdery, blocky and barreled) can be sent into the rotary kiln for incineration.

The incineration of hazardous wastes in rotary kilns generally goes through several stages, such as drying, pyrolysis, combustion and burnout. After these stages, hazardous components in hazardous wastes are fully decomposed and destroyed under high temperature, forming high-temperature flue gas and slag. These high-temperature flue gas and slag will cause corrosive damage to the refractory materials built in the rotary kiln.

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

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

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

(4) Thermal expansion stability is good. Although the thermal expansion coefficient of the rotary kiln shell is greater than the thermal expansion coefficient of the rotary kiln refractory, the shell temperature is generally about 150~300 ℃, and the temperature borne by the refractory is generally above 800 ℃, which may cause the refractory to be larger than the thermal expansion coefficient of the rotary kiln shell and easy to fall off.

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