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Acid-alkaline combined technology for pre-desiliconizing and extracting aluminium oxide from coal solid wastes

A solid waste, acid-base combination technology, applied in the removal of solid waste, alumina/aluminum hydroxide, silicon oxide, etc., can solve the problems of large sintering amount, difficult separation of aluminum and silicon, and high energy consumption

Active Publication Date: 2015-07-29
BEIJING GENERAL RES INST OF MINING & METALLURGY
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  • Abstract
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Problems solved by technology

[0005] The purpose of the present invention is to overcome the deficiencies in the existing techniques for extracting alumina from coal-based solid wastes such as fly ash and coal gangue, and provide a method of sulfuric acid conversion-high-temperature roasting activation-low-temperature alkali leaching pre-desilication-high-temperature alkali leaching aluminum The process is to pre-desilicate and extract alumina from coal-based solid waste such as fly ash and coal gangue. Specifically, it dissociates aluminum minerals and silicon minerals in minerals through sulfuric acid conversion, and decomposes aluminum sulfate into alumina through high-temperature roasting. and improve the alkali leaching activity of silicon dioxide in raw materials, and then desilicate silicon and aluminum through atmospheric pressure low-temperature alkali leaching and pressurized high-temperature alkali leaching, so as to realize the separate leaching of silicon and aluminum, which avoids the alumina production process of acid method The problems of poor product quality, concentrated crystallization of aluminum salts and high energy consumption for dehydration have also overcome the problems of difficult separation of aluminum and silicon, large sintering volume, high energy consumption, and large amount of red mud in the process of producing alumina by the alkaline method, and realized the acid method and Complementary advantages of alkaline process

Method used

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  • Acid-alkaline combined technology for pre-desiliconizing and extracting aluminium oxide from coal solid wastes

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Experimental program
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Effect test

Embodiment 1

[0027] The fly ash containing 48% of alumina and 42% of silicon dioxide is mixed with sulfuric acid, and the amount of sulfuric acid added is Al in the fly ash 2 o 3 3.5 times the number of moles, and the mass concentration of sulfuric acid used is 90%. After mixing evenly, acidolysis and solidification are carried out at 250°C. The reaction time is 2h. Na for calcination 2 O concentration 100g / L sodium hydroxide solution leaching, leaching solid-liquid mass and volume ratio 1:10, leaching temperature 85 ℃, leaching time 60min, filter and obtain silicon-containing leaching solution and high-alumina slag, the leaching rate of silicon is 75%; The obtained high alumina slag was treated with Na 2 Sodium hydroxide solution with an O concentration of 200g / L leaches aluminum, the leaching solid-liquid mass-to-volume ratio is 1:5, and the ingredient molecular ratio is α k 1.4, the amount of lime added is 5% of the mass of high aluminum slag, the leaching temperature is 250°C, the l...

Embodiment 2

[0029] The fly ash containing 48% of alumina and 42% of silicon dioxide is mixed with sulfuric acid, and the amount of sulfuric acid added is Al in the fly ash 2 o3 4.5 times the number of moles, and the mass concentration of sulfuric acid used is 95%. After mixing evenly, acidolysis and solidification are carried out at 300°C for 2 hours. Na for calcination 2 O concentration 50g / L sodium hydroxide solution leaching, leaching solid-liquid mass and volume ratio 1:5, leaching temperature 85 ℃, leaching time 60min, filter and obtain silicon-containing leaching solution and high-alumina slag, the leaching rate of silicon is 60%; The obtained high aluminum slag is Na 2 Sodium hydroxide solution with an O concentration of 200g / L leaches aluminum, the leaching solid-liquid mass-to-volume ratio is 1:5, and the ingredient molecular ratio is α k 1.4, the amount of lime added is 10% of the mass of high aluminum slag, the leaching temperature is 250°C, the leaching time is 30min, and th...

Embodiment 3

[0031] Grind coal gangue containing 38% of alumina and 48% of silicon dioxide to 0.1mm and mix it with sulfuric acid. The amount of sulfuric acid added is the amount of Al in the fly ash 2 o 3 3.5 times the number of moles, and the mass concentration of sulfuric acid used is 95%. After mixing evenly, acidolysis and solidification are carried out at 300°C for 2 hours. Na for calcination 2 O concentration 100g / L sodium hydroxide solution leaching, leaching solid-liquid mass and volume ratio 1:10, leaching temperature 85 ℃, leaching time 60min, filter and obtain silicon-containing leaching solution and high-alumina slag, the leaching rate of silicon is 68%; The obtained high aluminum slag is Na 2 Sodium hydroxide solution with an O concentration of 200g / L leaches aluminum, the leaching solid-liquid mass-to-volume ratio is 1:5, and the ingredient molecular ratio is α k 1.4, the leaching temperature is 250°C, the leaching time is 30min, and the aluminum leaching rate is 82%. Af...

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Abstract

An acid-alkaline combined technology for pre-desiliconizing and extracting aluminium oxide from coal solid wastes comprises the following steps: uniformly stirring coal ash or coal gangue by using a certain amount of concentrated sulfuric acid, performing acidolysis and solidification at the temperature of 120-500 DEG C, and then, quickly roasting at the temperature of 900-1200 DEG C for 0.1-60 min, so as to obtain roasted products and sulfur-containing flue gas; performing normal-pressure and low-temperature alkaline leaching pre-desiliconization on the roasted products to obtain high alumina slag, then, extracting aluminium oxide from the high alumina slag by adopting pressurized high-temperature alkaline leaching. According to the invention, through high-temperature quick roasting, the normal-pressure alkaline leaching pre-desiliconization effect is improved, and the activity of leached aluminium oxide is guaranteed, so that the complementary advantages of the acid process and the advantages of the alkaline process are achieved.

Description

technical field [0001] The invention belongs to the comprehensive utilization of coal-based solid wastes, and in particular relates to a method for extracting alumina and silicon oxide from coal-based solid wastes such as fly ash and coal gangue, especially through sulfuric acid conversion of coal-based solid wastes in sequence , high-temperature roasting activation, low-temperature alkali leaching pre-desilication, high-temperature alkali leaching of aluminum and other steps to extract alumina and silica from coal-based solid waste. Background technique [0002] Coal-based solid waste mainly refers to coal gangue, fly ash, etc. produced during coal mining and utilization. The main components of this type of solid waste are alumina and silica. Due to the lack of clean and economical utilization solutions, currently A small amount of ash is used in the production of building materials, and most of it is stockpiled. The efficient and economical extraction of useful components ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F7/02C01B33/12B09B3/00
Inventor 蒋训雄蒋开喜汪胜东范艳青张登高蒋伟冯林永刘巍靳冉公周立杰王爱平
Owner BEIJING GENERAL RES INST OF MINING & METALLURGY
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