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Method for extracting aluminum oxide from fly ash by acid-alkali combination process

A technology of acid-base combination and fly ash, which is applied in the direction of alumina/aluminum hydroxide, etc., can solve the problems of large amount of leached slag, high energy consumption, and low purity of alumina products, so as to reduce the amount of leached slag and avoid sintering Process effect

Active Publication Date: 2015-03-25
BEIJING GENERAL RES INST OF MINING & METALLURGY
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  • Abstract
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Problems solved by technology

[0009] The purpose of the present invention is to overcome the deficiencies in the existing technology for extracting alumina from fly ash, and to provide a method for extracting alumina from fly ash using an acid-base combination method. In the ash acid treatment process, the problems of high energy consumption of aluminum salt concentration crystallization and pyrolysis, and low purity of alumina products are avoided, while avoiding the defects of large amount of sintered materials, high energy consumption, and large amount of leached slag in the fly ash alkali treatment process

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  • Method for extracting aluminum oxide from fly ash by acid-alkali combination process

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Effect test

Embodiment 1

[0042] Mix the fly ash with sulfuric acid, the amount of sulfuric acid added is 1.5 times the mass of the fly ash, and the sulfuric acid concentration used is 90%. After mixing evenly, the sulfuric acid clinker is obtained under the conditions of a curing temperature of 200° C. and a curing time of 8 hours. The sulfuric acid slaking material is mixed evenly according to the coal ratio of 8%, and the rapid reduction roasting is carried out at a temperature of 750 ° C for 5 minutes.

[0043] Alkali leaching is carried out on the reduced calcine, and the dissolution conditions are: dissolution temperature 100°C, alkali concentration 50g / L, ingredient molecular ratio α k 0.9, time 60min, lime addition 0%. At this time, the actual dissolution rate of aluminum was 83%. The dissolution liquid was sorted to obtain aluminum hydroxide product, which was calcined to prepare metallurgical grade alumina product, and the sorted mother liquor was returned to calcined sand for dissolution.

Embodiment 2

[0045] Fly ash was mixed with sulfuric acid, the amount of sulfuric acid added was 2.2 times the mass of the fly ash, and the concentration of sulfuric acid used was 93%. After mixing evenly, the sulfuric acid clinker was obtained under the conditions of a curing temperature of 320° C. and a curing time of 8 hours. The sulfuric acid slaking material is uniformly mixed with coal powder at a coal ratio of 15%, and is subjected to rapid reduction roasting at a temperature of 800°C, and the roasting time is 10 minutes.

[0046] Alkali leaching is carried out on the reduced calcine, and the dissolution conditions are: dissolution temperature 90°C, alkali concentration 70g / L, ingredient molecular ratio α k 1.2, time 40min, lime addition 2%. At this time, the actual dissolution rate of aluminum is 92%, and the stripping solution is sorted to obtain aluminum hydroxide products, which are calcined to prepare metallurgical grade alumina products, and the sorting mother liquor is returne...

Embodiment 3

[0048] Fly ash was mixed with sulfuric acid, the amount of sulfuric acid added was 1.8 times the mass of the fly ash, and the concentration of sulfuric acid used was 93%. After mixing evenly, the sulfuric acid clinker was obtained under the conditions of a curing temperature of 380° C. and a curing time of 4 hours. The sulfuric acid slaking material is passed into the gas in the fluidized roasting furnace, and the rapid reduction roasting is carried out at a temperature of 750 ° C, and the roasting time is 1 min.

[0049] Alkali leaching is carried out on the reduced calcine, and the dissolution conditions are: dissolution temperature 150°C, alkali concentration 50g / L, ingredient molecular ratio α k 0.9, time 60min, lime addition 0%. At this time, the actual dissolution rate of aluminum is 85%, and the stripping solution is sorted to obtain aluminum hydroxide products, which are calcined to prepare metallurgical grade alumina products, and the sorting mother liquor is returned...

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Abstract

The invention discloses a method for extracting aluminum oxide from fly ash by an acid-alkali combination process. The method comprises the following steps of uniformly mixing and curing fly ash and an appropriate amount of concentrated sulfuric acid, by virtue of residual carbon in the fly ash and appropriately supplementing a reducing agent, carrying out high-temperature rapid reduction, calcining and desulfurization, preparing sulfur-containing flue gas into acid to achieve regeneration recycling of sulfuric acid and producing aluminum oxide from the reduced calcined product by virtue of alkaline leaching. According to the method, advantages of fly ash acid method and alkali method for extracting aluminum oxide are integrated and shortcomings of both are effectively avoided. High-energy-consumption evaporative crystallization of aluminum salt and decomposition process of aluminum salt crystallization water in the conventional acid method process are omitted and thus a great deal of energy consumption is saved; compared with the conventional alkali method process, high-energy-consumption calcining process is not needed, the amount of slag is low and the slag can be used as a silicon raw material for recycling, the yield of wastes is small and thus the real reduction environment-friendly clean product is achieved; the aluminum oxide product has good quality, the method has the advantages of high recovery rate, low energy consumption and small corrosion to the device and the large-scale industrialization is easily implemented.

Description

technical field [0001] The invention belongs to the comprehensive utilization of fly ash, and in particular relates to a method for extracting alumina from fly ash, in particular to extracting alumina by using an acid-base combined process. Background technique [0002] With the rapid development of modern industry, resource scarcity has become one of the main social problems facing people. The raw material for producing alumina is mainly bauxite. The traditional smelting method is the production of alumina by the alkali method. The silicon oxide in the ore is the main harmful element in the production by the alkali method. The ratio of aluminum to silicon in the bauxite is required to be A / S (ore Middle Al 2 o 3 with SiO 2 mass ratio) greater than 3. The alkali method is divided into Bayer method, sintering method and combined method, among which Bayer method is suitable for processing Al-containing 2 o 3 High, SiO 2 Low bonanza, generally requires Al 2 o 3 >65%...

Claims

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Application Information

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IPC IPC(8): C01F7/02
CPCC01F7/02
Inventor 蒋开喜蒋训雄汪胜东范艳青李达
Owner BEIJING GENERAL RES INST OF MINING & METALLURGY
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