Method for secondary acid leaching of alumina in coal ash residues

A technology for coal ash slag and acid leaching slag, which is applied in the directions of silicate, alkali metal silicate, process efficiency improvement, etc. , low coal ash activity, etc., to achieve the effect of high labor productivity, advanced technology, and low pollution

Inactive Publication Date: 2014-07-30
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The coal ash produced in these two cases is due to the low content of amorphous aluminum and silicon, which leads to low activity of coal ash, which affects the extraction of aluminum and silicon from coal ash.

Method used

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  • Method for secondary acid leaching of alumina in coal ash residues

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Experimental program
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Effect test

Embodiment 1

[0027] The aluminum-containing coal ash used is the bottom slag discharged after combustion in a circulating fluidized bed, and its chemical composition (mass fraction) is: SiO 2 59.38%, Al 2 o 3 27.34%, Fe 2 o 3 6.71%, CaO0.23%, MgO0.59%, K 2 O4.28%, Na 2 O0.58%, TiO 2 0.39%. Analysis of the occurrence state of aluminum in ash slag shows that part of aluminum exists in the form of amorphous state, and the other part of aluminum occurs in microplagioclase crystals.

[0028] The leaching steps of coal ash are as follows:

[0029] (1) One-time acid leaching: add 200mL of 10mol / L sulfuric acid solution into the flask, heat it to 120°C in an oil bath magnetic stirrer, add 100g of aluminum-containing lime ash, soak for 2 hours, filter and wash to obtain Aluminum-containing primary acid leaching solution and primary acid leaching residue;

[0030] (2) Roasting activation: the primary acid leaching residue contains SiO 2 83.14%, Al 2 o 3 8.33%, based on the molar ratio of...

Embodiment 2

[0035] The aluminum-containing coal ash used is the bottom slag discharged after combustion in the circulating fluidized bed, and its chemical composition is: SiO 2 59.38%, Al 2 o 3 27.34%, Fe 2 o 36.71%, CaO0.23%, MgO0.59%, K 2 O4.28%, Na 2 O0.58%, TiO 2 0.39%. Analysis of the occurrence state of aluminum in ash slag shows that part of aluminum exists in the form of amorphous state, and the other part of aluminum occurs in microplagioclase crystals.

[0036] The leaching steps of coal ash are as follows:

[0037] (1) One-time acid leaching: add 200mL of 10mol / L sulfuric acid solution in the flask, heat it to 140°C in an oil bath magnetic stirrer, add 100g of aluminum-containing lime ash, soak for 2 hours, filter and wash to obtain Aluminum-containing primary acid leaching solution and primary acid leaching residue;

[0038] (2) Roasting activation: the primary acid leaching residue contains SiO 2 84.31%, Al 2 o 3 8.12%, based on the molar ratio of anhydrous sodium...

Embodiment 3

[0043] The aluminum-containing coal ash used is the bottom slag discharged after combustion in the circulating fluidized bed, and its chemical composition is: SiO 2 59.38%, Al 2 o 3 27.34%, Fe 2 o 3 6.71%, CaO0.23%, MgO0.59%, K 2 O4.28%, Na 2 O0.58%, TiO 2 0.39%. Analysis of the occurrence state of aluminum in ash slag shows that part of aluminum exists in the form of amorphous state, and the other part of aluminum occurs in microplagioclase crystals.

[0044] The leaching steps of coal ash are as follows:

[0045] (5) One-time acid leaching: add 200mL of 10mol / L sulfuric acid solution into the flask, heat it to 120°C in an oil bath magnetic stirrer, add 100g of aluminum-containing lime ash, soak for 2 hours, filter and wash to obtain Aluminum-containing primary acid leaching solution and primary acid leaching residue;

[0046] (6) Roasting activation: the primary acid leaching residue contains SiO 2 83.14%, Al 2 o 3 8.33%, based on the molar ratio of anhydrous sod...

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Abstract

The invention provides a method for secondary acid leaching of alumina in coal ash residues. The method comprises the following steps of carrying out direct acid leaching on coal ash residues to obtain an aluminum ion-containing primary acid leaching liquid and aluminum crystal-containing primary acid leaching residues, carrying out calcination on the aluminum crystal-containing primary acid leaching residues added with sodium carbonate so that aluminum-containing crystals in the aluminum crystal-containing primary acid leaching residues are destroyed, carrying out water leaching on the calcined clinker to obtain a sodium silicate solution and aluminum-containing water leaching residues, carrying out secondary acid leaching treatment on the aluminum-containing water leaching residues and feeding the residual aluminum into the secondary acid leaching liquid. The total leaching efficiency of the two aluminum acid-leaching processes is more than 98%. The method has the advantages of good operation conditions, wide coal ash residue application range, no waste residue, high resource utilization rate, low comprehensive cost, good benefits and less pollution.

Description

(1) Technical field [0001] The present invention relates to a method for leaching alumina from coal ash, more specifically, relates to a method for leaching alumina in coal ash by acid leaching. (2) Background technology [0002] Aluminum and aluminum alloys are currently one of the most economically applicable materials that are widely used. Since 1956, the world's aluminum output has surpassed that of copper, and it has always ranked first in non-ferrous metals. The current output and consumption of aluminum (calculated by ton) is second only to steel, and has become the second largest metal used by human beings; moreover, aluminum resources are very abundant. According to preliminary calculations, the mineral reserves of aluminum account for more than 8% of the earth's crust. . However, China's bauxite resources are scarce, and the proven reserves are only 3.2 billion tons. According to the current mining scale, the resource guarantee period is about 20 years, which is ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22B7/00C22B21/00C01B33/32
CPCY02P10/20
Inventor 骆仲泱施正伦方梦祥高翔王勤辉程乐鸣周劲松余春江王树荣肖刚王涛祝培旺倪明江岑可法
Owner ZHEJIANG UNIV
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