CN112121611A - A kind of method for preparing cement kiln flue gas purifying agent from aluminum ash - Google Patents

Abstract

The patent discloses a method for preparing a cement kiln flue gas purifying agent from aluminum ash. The method has low production cost and high efficiency, and realizes high-quality cyclic utilization of resources.

Description

A kind of method for preparing cement kiln flue gas purifying agent from aluminum ash

technical field

The invention relates to the field of resource utilization of non-ferrous solid waste, in particular to the application of aluminum ash to prepare a cement kiln flue gas purifier.

Background technique

Aluminum ash is a product of the aluminum melting and casting process. According to the different raw materials and production purposes used for aluminum casting, the composition and content of aluminum ash will be quite different. The aluminum ash produced by using electrolytic aluminum solution to produce remelted aluminum ingots accounts for about 1.1% of the ingot output. The composition is relatively simple and stable, mainly composed of metal aluminum, alumina, aluminum nitride, chloride salt (sodium chloride , potassium chloride) and electrolyte (sodium fluoride, calcium fluoride, cryolite, etc.), of which aluminum accounts for about 40%-50%, alumina accounts for about 30%-40%; In addition to metal aluminum, alumina, aluminum nitride, chloride salts and electrolytes, there are other elements and oxides of varying amounts and types in the ash [Liu Zhansheng, Liang Xuemin, Lu Zhifeng. Formation and Evolution of Components in Aluminum Ash Brief Analysis [J]. Hunan Nonferrous Metals, 2019, 35(5): 58-60].

The aluminum particles contained in the aluminum ash have the characteristics of large surface area and high activity, and are easy to react with water or in a humid environment to generate hydrogen; the aluminum nitride in the aluminum ash generates ammonia gas when it encounters water. Hydrogen and ammonia are both reducing gases, which are prone to explosion in the presence of oxygen and open fire, and ammonia has a pungent odor, which is one of the main reasons for the environmental hazard of aluminum ash. In addition to its reactivity, the leaching toxicity test found that the dissolved fluoride ions in the tested aluminum ash samples exceeded the standard, and the excessive discharge of fluoride ions had serious harm to water bodies, soil, animals and plants. Problems that need to be solved in comprehensive disposal technology [Jiao Zhiwei, Liu Wei, Zhang Tao, et al. Research on attribute identification of aluminum ash solid waste in aluminum smelting enterprises [J]. Modern Metallurgy, 2019, 47(4): 19-21].

Usually, according to the different content of metal aluminum in aluminum ash, it can be divided into primary aluminum ash and secondary aluminum ash. The aluminum slag extracted from the smelting furnace is called primary aluminum ash, which is gray-white in appearance. It is mainly a mixture of metal aluminum and aluminum oxide, and the aluminum content can reach 15%-70%. Secondary aluminum ash is the waste after primary aluminum ash extraction of metal aluminum, the main components are alumina, aluminum nitride, metal aluminum, salts and other components, because it is consolidated into a block, also known as For "salt cake" [Li Shuai, Liu Wanchao, Liu Zhongkai, et al. Status and Prospect of Aluminum Ash Treatment Technology [J]. Nonferrous Metals (Smelting Section), 2018, (10): 25-29].

The aluminum ash used in this patent is the secondary aluminum ash after the primary aluminum ash is extracted from metal aluminum. In view of the problems that the secondary aluminum ash cannot be used in high value, the patent provides a method for preparing a cement kiln flue gas purifier from aluminum ash, which promotes High-value utilization of ash.

SUMMARY OF THE INVENTION

In order to solve the problems existing in the prior art, the present invention provides a method for preparing a cement kiln flue gas purifying agent from aluminum ash. economic and social benefits.

A method for preparing a cement kiln flue gas purifying agent from aluminum ash, comprising the following steps: adding calcium source and sodium source to aluminum ash to mix uniformly, and calcining in a nitrider to obtain a flue gas purifying agent.

The calcium source is one of limestone, calcium carbide slag and marble powder, and the added amount is 10-30% of the mass of aluminum ash.

The sodium source is one of Glauber's salt and saltpeter, and the added amount is 10-30% of the mass of aluminum ash.

The nitrider is a suspension calciner.

The calcination temperature is 800-1100°C.

Compared with the prior art, the present invention has the following advantages:

The calcium source is one of limestone, carbide slag, and marble powder. During the calcination process, the calcium source is decomposed into calcium oxide. The calcium oxide can react with the aluminum oxide in the aluminum ash to form calcium aluminate, which oxidizes the oxide coated on the surface of the metal aluminum. The rupture of the aluminum film is conducive to the nitridation of metal aluminum to form aluminum nitride.

The sodium source is one of Glauber's salt and saltpeter. During the calcination process, the sodium source can also react with the aluminum oxide in the aluminum ash to form sodium aluminate, which will break the aluminum oxide film wrapped on the surface of metal aluminum and promote the formation of metal aluminum nitridation. Aluminum Nitride. The nitrider is a suspension calciner, which consists of a preheater and a boiling furnace, and has the characteristics of high thermal efficiency and low investment. The number of stages of the preheater is 2-6, which is designed according to the principle of the preheater commonly used in precalcining cement kilns. The principle of the boiling furnace is a columnar spouted turbulent bed, which is a cylindrical unit with a constriction. The ratio of the inner diameter of the cylindrical unit to the inner diameter of the constricted is 1.1:1-1.8:1, and the ratio of the height of the cylindrical unit to the inner diameter of the cylinder is 1:1-4:1. The fuel for calcination is one of waste oil, coal and waste plastic, which indirectly heats the materials in the boiling furnace. Using waste oil and waste plastics as fuel can realize resource recycling. The gas in contact with the material in the nitrider is nitrogen, which is separated from the air. The oxygen separated from the air is used for fuel combustion, which is conducive to increasing the temperature of the flue gas, and the generated flue gas is mainly carbon dioxide, which is conducive to recycling.

The main phases of the obtained flue gas purifying agent are aluminum nitride and calcium aluminate. Water is added to the flue gas purifying agent, and the water reacts with aluminum nitride to release ammonia gas; calcium aluminate reacts with water to release calcium hydroxide, which promotes nitrogen Aluminium reacts with water and ammonia gas is released from the aqueous solution, and the produced ammonia gas is used for denitrification of cement kiln flue gas to eliminate nitrogen oxides in flue gas. In addition, the sodium source in the flue gas purification agent can be used as a catalyst for the reaction between aluminum nitride and water, and the reaction rate of this reaction is 100%. The precipitation produced by the reaction between the flue gas purifier and water can be used as the raw material of cement to realize the full utilization of resources. The flue gas purifier is solid and is easy to transport.

Detailed ways

The present invention will be further described in detail below in conjunction with specific embodiments.

The calcium source and the sodium source are added to the aluminum ash and mixed evenly, and the flue gas purifier is obtained by calcining in the nitrider. The formulas and calcination temperature of calcium source and sodium source are shown in Table 1.

Table 1

In the aluminum ash, metal aluminum is converted into aluminum nitride, and aluminum oxide is converted into calcium aluminate, and the conversion rates are all 100%; the embodiments of the present invention can be implemented and can achieve the purpose of the invention. The present invention is not limited to these examples.

Claims (5)

1. a method for preparing cement kiln flue gas purifying agent by aluminum ash, is characterized in that, comprises the following steps: adding calcium source, sodium source in aluminum ash and mixing uniformly, calcining in nitrider to obtain flue gas purifying agent. 2. the method for preparing cement kiln flue gas purifying agent by a kind of aluminium ash according to claim 1, is characterized in that, described calcium source is a kind of in limestone, calcium carbide slag, marble powder, and the add-on is the quality of aluminium ash 10-30%. 3. the method for preparing cement kiln flue gas purifying agent by a kind of aluminium ash according to claim 1, it is characterized in that, described sodium source is a kind of in Glauber's salt, saltpeter, and the add-on is 10-30 of aluminium ash quality %. 4 . The method for preparing a cement kiln flue gas purifying agent from aluminum ash according to claim 1 , wherein the nitrider is a suspension calciner. 5 . 5 . The method for preparing cement kiln flue gas purifying agent from aluminum ash according to claim 1 , wherein the calcination temperature is 800-1100° C. 6 .