An internal gas fired shaft kiln and method for producing light-fired magnesia

Abstract

The invention discloses an internal gas-fired vertical kiln for producing light-burned magnesia. The furnace body of the vertical kiln includes a preheating section, a constant temperature section and a cooling section from top to bottom, and the central constant temperature section of the furnace body is It is a drum-shaped protrusion, and the center of the constant temperature section is provided with an inner cylinder burner. The inner cylinder burner is conical and the top and bottom are respectively combined with the furnace wall through a cross platform; the cooling section at the lower part of the furnace body A gas inlet is provided on the side of the upper part, and an air inlet is provided on the side of the lower part of the cooling section. The method of the present invention comprises the following steps: putting the magnesite raw material with a particle size range of 30-80mm into the shaft kiln, drying and preheating the flue gas at about 250-300°C for 20min; Calcining at lower temperature for 30-45 minutes; blowing combustion-supporting air into the air inlet of the shaft kiln; the temperature of the cooled material is 150-200°C, and it is discharged from the furnace through the discharge port at the bottom of the furnace. The vertical kiln and the production method of the invention have low energy consumption, high heat utilization rate, high product added value, and the obtained product has good activity.

Description

technical field [0001] The invention relates to the technical field of nonferrous metal smelting, in particular to an internal gas-fired shaft kiln and a method for producing light-burned magnesia. Background technique [0002] China is the country with the most abundant magnesite resources in the world, with a total reserve of 3 billion tons of ore, ranking first in the world. Among them, Liaoning magnesite reserves are the most abundant, accounting for 85.6% of the country's total, mainly concentrated in Dashiqiao and Haicheng. Magnesite is the main raw material for the production of magnesium compounds. Light-burned magnesium is obtained by calcination of magnesite. It is widely used in many fields such as building materials, chemical industry, metallurgy, and medicine. It is an ideal material for magnesium sulfate, papermaking, desulfurization process, steel plant protection furnace slag splashing, etc. It is also a raw material for producing dead-burned magnesium, high...

AI Technical Summary

Problems solved by technology

[0003] The existing kiln used for the production of light-burned magnesia is a traditional vertical kiln composed of a steel shell and a refractory brick lining or an earth kiln made of only refractory bricks. During the production process, coal and large stones are loaded in layers Put it into the kiln from the top of the kiln, the air is introduced from the lower part of the kiln, and the raw material blocks are gradually moved down by gravity. After a certain period of calcination, the light-burned magnesium product is obtained. It is discharged from the bottom of the kiln, and the product quality cannot be guaranteed.

[0004] There are many disadvantages in the production of light-burned magnesium in this kind of kiln: (1) The utilization rate of raw materials is not high, and the input particle size is mostly lumps with a particle size of 100-300 mm. Large, uneven heat transfer, local under-combustion often occurs, resulting in resource waste and product quality decline, and high energy consumption; Oxygen required for combustion will cause incomplete combustion of coal, or excessive combustion due to low coal content, resulting in local high temperature phenomenon and partial overburning of materials; (3) Low degree of automation and serious environmental pollution

It is mainly reflected in the unorganized emission of dust and smoke, which not only pollutes the surrounding environment, but also causes health damage to local residents and staff; (4) It is mainly reflected in the low content of lightly burned magnesium in the product, low activity, and low added value of the product high

[0005] The existing light-burned magnesium industry is also relatively backward in technology, mainly in small-scale production. Most of the incoming materials are blocks with a particle size of 100-300mm, which are directly placed in a vertical kiln for calcination for 1.5-2 hours, and the product is obtained after cooling. Due to the particle size Large, uneven heat transfer, under-burning often occurs, and a large amount of powder is discarded, causing environmental pollution and low resource utilization

Due to the above-mentioned extensive production process, the content of light burned magnesium products is low, the activity is low, and the added value of the product is low, which wastes high-quality magnesite resources. At the same time, the energy consumption in the production process is high, and the recovery and utilization of waste heat are not paid attention to.

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