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Sulfuric acid activation-hydrogen chloride crystallization method for joint production of high-purity alumina

A high-purity alumina and co-production technology, applied in the field of fly ash treatment, can solve the problems of difficult removal of impurities in the acidic system environment, short process flow, low activation temperature, etc., to solve material corrosion, high energy consumption, and short process flow , The effect of simple process

Active Publication Date: 2018-08-10
ACADEMY OF AEROSPACE PROPULSION TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Alkali method mainly includes alkali dissolution method, limestone sintering method, soda lime sintering method, high temperature sintering-microwave radiation method, etc. The process flow is long, energy consumption is high, equipment investment is large, and the amount of residue generated is several times that of fly ash, which is easy to cause secondary pollution
The acid leaching method mainly adopts hydrochloric acid or sulfuric acid leaching method. This method has a low activation temperature and a short process flow. However, due to the dissolution of impurities such as sodium, potassium, iron, magnesium, and calcium, it is difficult to remove impurities in an acidic system environment, and the cost is high. Miscellaneous has become the key to restricting the industrial application and promotion of the acid process. In addition, it was generally believed that the silicon dioxide in the fly ash would not dissolve in the acidic environment, and the acid process would not have the problem of desiliconization. However, the test proved that the fly ash Strong acid activation treatment, the silicon of the alumina product produced still exceeds the standard, and desiliconization is also a specific problem that needs to be faced in the acid method aluminum extraction process

Method used

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  • Sulfuric acid activation-hydrogen chloride crystallization method for joint production of high-purity alumina

Examples

Experimental program
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Effect test

Embodiment 1

[0068] 100kg of fly ash (containing 52.9% alumina) was dried at 120°C for 30 minutes, transferred to a reaction kettle, 372kg of 86% sulfuric acid was added, and the reaction was stirred at 330°C for 2.4 hours. Stand still for 4 minutes, pour out the sulfuric acid in the upper layer, and recycle the poured hot sulfuric acid, add 440 kg of water to the reaction kettle, heat and stir at 180°C, react for 1 hour, separate solid and liquid, wash the filter residue with 80 kg of water, wash water for redissolution reactions. The aluminum sulfate solution passes through a positive pressure filter with a 0.1 μm filter membrane at a pressure of 0.04 MPa for desiliconization; when the filtrate is at normal temperature, press 6 m 3 HCl gas is fed at a flow rate of / h, and the reaction temperature is controlled at 30°C until the HCl gas in the solution + When the ion concentration reaches 12.5mol / L, the impurity removal crystallization is completed, the aeration is stopped, and after cen...

Embodiment 2

[0070] 100kg of fly ash (containing 52.9% alumina) was dried at 120°C for 30 minutes, transferred to a reaction kettle, 580kg of 96% sulfuric acid was added, and the reaction was stirred at 250°C for 1.4 hours. Stand still for 4 minutes, pour out the sulfuric acid in the upper layer, and recycle the poured hot sulfuric acid, add 420 kg of water to the reaction kettle, heat and stir at 120 ° C, react for 1.2 hours, separate solid and liquid, wash the filter residue with 90 kg of water, wash water for redissolution reactions. The aluminum sulfate solution passes through a positive pressure filter with a 0.1 μm filter membrane at a pressure of 0.05 MPa for desiliconization; when the filtrate is at normal temperature, press 12 m 3 HCl gas is fed at a flow rate of / h, and the reaction temperature is controlled at 30°C until the HCl gas in the solution + When the ion concentration reaches 12.5mol / L, the impurity-removing crystallization is completed, the ventilation is stopped, cen...

Embodiment 3

[0072] 100kg of fly ash (containing 52.9% alumina) was dried at 120°C for 30 minutes, transferred to a reaction kettle, added with 370kg of 90% sulfuric acid, and stirred at 280°C for 2 hours. Stand still for 4 minutes, pour out the upper layer of sulfuric acid, and recycle the poured hot sulfuric acid. Add 420 kg of water to the reaction kettle, heat and stir at 150 ° C, react for 1.5 hours, separate solid and liquid, wash the filter residue with 85 kg of water, wash the water for redissolution reactions. The aluminum sulfate solution passes through a positive pressure filter with a 0.1 μm filter membrane at a pressure of 0.05 MPa for desiliconization; when the filtrate is at normal temperature, press 18 m 3 HCl gas is fed at a flow rate of / h, and the reaction temperature is controlled at 30°C until the HCl gas in the solution + When the ion concentration reaches 12.5mol / L, the impurity removal crystallization is completed, the aeration is stopped, and after centrifugation,...

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Abstract

The invention relates to a method using sulfuric acid activating and HCl (hydrogen chloride) crystallizing to jointly produce high-purity aluminum oxide. The method specifically comprises the following steps of drying the fly ash raw material, extracting by concentrated sulfuric acid and thermally activating, dissolving by water, specially filtering under the acid conditions, sending HCl gas to remove impurities, and separating an aluminum chloride crystal; filtering and washing the crystal, calcining the crystal into a product, recycling filtrate, and circulating. The method has the advantages that the slurry is activated in a reaction kettle, and the industrial efficiency is high; the special filtering and deep silicon removal cost is low, the impurity removal and crystallizing by sending HCl are simultaneously completed, the filtrate is recycled and circulated, the whole technology process is short, and the energy consumption is low; the material is fully recycled, and the discharging of waste gas and waste liquid is avoided; the impurity removal and crystallizing are completed at one step, so that the problems of difficulty in activating of fly ash of a fly ash furnace, and difficulty in removal of metal impurity ions and thorough silicon removal under the acid condition are solved; the whole process has passed the running test of 100kg of fly ash per batch, the purity of produced aluminum oxide is 99.95% or above, the foreseen industrial technical problems are avoided, and the economic and social benefits are obvious.

Description

technical field [0001] The invention belongs to the technical field of fly ash treatment, and in particular relates to a method for combined production of high-purity alumina by sulfuric acid activation and hydrogen chloride crystallization. Background technique [0002] There are a large amount of aluminum-containing minerals in some coal resources in central and western Inner Mongolia, northern Shanxi, and Ningxia. The chemical composition of the fly ash generated by these high-alumina coals mainly includes Al 2 o 3 , SiO 2 , Fe 2 o 3 , CaO, K 2 O, Na 2 O etc., where Al 2 o 3 The content is about 50%, which is equivalent to intermediate grade bauxite. At the same time, with the rapid development of my country's aluminum industry, the scale of alumina production has continued to expand, the consumption of bauxite has increased year by year, and the contradiction of resource shortage has become increasingly prominent. It has been found that my country's bauxite reso...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01F7/30
CPCC01F7/30C01P2006/80
Inventor 曾伟梁兴国杨超徐涛李宁兰海平隽军科吴永刚高璇王辉
Owner ACADEMY OF AEROSPACE PROPULSION TECH