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Fly Ash Carbonate Solution Pretreatment and Alumina Extraction Method

A technology of fly ash and carbonate, applied in the preparation of alkali metal aluminate/alumina/aluminum hydroxide, etc., can solve the problem of unstable sulfation conversion rate of alumina, affecting the quality and process of alumina in sorting operations Problems such as complex process can be solved to achieve the effect of improving the utilization rate of sulfuric acid, avoiding the kiln formation of materials, and improving product quality

Active Publication Date: 2019-09-10
BEIJING GENERAL RES INST OF MINING & METALLURGY
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  • Abstract
  • Description
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AI Technical Summary

Problems solved by technology

CN103086410A discloses a method for preparing alumina by mixing and roasting fly ash ammonium sulfate, the process includes raw material preparation, clinker firing, clinker dissolution, high-silicon slag separation and washing, aluminum ammonium sulfate solution for one-time iron removal, aluminum ammonium sulfate Secondary iron removal from solution, reduction of primary iron removal refined solution, solution decomposition of ammonium aluminum sulfate refined solution, separation and washing of crude aluminum hydroxide, desulfurization of crude aluminum hydroxide, separation and washing of aluminum hydroxide and roasting of aluminum hydroxide, etc., the process is complex
Because the sour ash is relatively large during slaking batching, the material in the slaking process is easy to kiln kiln. CN104787788A discloses a method for producing alumina from high-alumina fly ash. It can solve the kiln kiln problem by mixing acid in batches, but the process is complicated and the alumina sulfuric acid The conversion rate is not stable
[0007] In addition, due to the existence of calcium, potassium, sodium, etc., the fly ash or the fly ash after re-roasting contains a small amount of sulfur. If this part of sulfur is not removed in advance, when the Bayer process is used to produce alumina, it will not only lead to Alkali consumption increases, and because of its continuous accumulation in the process, it affects the subsequent sorting operation and alumina quality

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  • Fly Ash Carbonate Solution Pretreatment and Alumina Extraction Method

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Experimental program
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Effect test

Embodiment 1

[0034]Mix the fly ash of the circulating fluidized bed with concentrated sulfuric acid with a concentration of 93% evenly, raise the temperature to 100°C at a rate of 1°C / min, keep the temperature for 0.5h, then raise the temperature to 200°C and roast for 1h to obtain sulfated clinker. The amount of concentrated sulfuric acid added is based on the amount of H in sulfuric acid 2 SO 4 Al with fly ash 2 o 3 Add in a molar ratio of 3.5:1; mix the sulfated clinker with an appropriate amount of pulverized coal evenly, the amount of pulverized coal added is adjusted according to the alumina content in the fly ash and the amount of residual carbon in the fly ash, and then at 850°C Reduction roasting for 15 minutes to obtain reduced calcined sand; mixing and slurrying the reduced calcined sand with sodium carbonate solution at 80°C for 60 minutes, filtering to obtain pretreated calcined sand; The solution was leached at 100°C for 1 hour, filtered to obtain a sodium aluminate soluti...

Embodiment 2

[0036] After mixing the circulating fluidized bed fly ash and concentrated sulfuric acid with a concentration of 90%, the temperature is raised to 150°C at a rate of 2°C / min, and after holding for 0.5h, the temperature is raised to 250°C and roasted for 1h to obtain sulfated clinker Material, the addition amount of concentrated sulfuric acid is according to H in sulfuric acid 2 SO 4 Al with fly ash 2 o 3 Add in a molar ratio of 3.5:1; mix the sulfated clinker with an appropriate amount of pulverized coal evenly, the amount of pulverized coal added is adjusted according to the alumina content in the fly ash and the amount of residual carbon in the fly ash, and then at 750°C Reduce and roast for 15 minutes to obtain reduced calcine; mix and slurry the reduced calcine with sodium carbonate solution at 80°C for 60 minutes, filter to obtain pretreated calcine; use pretreated calcine with sodium hydroxide concentration of 150g / L The lye is leached at 100°C for 1 hour, filtered to...

Embodiment 3

[0038] After mixing the circulating fluidized bed fly ash and concentrated sulfuric acid with a concentration of 85%, the temperature was raised to 100°C at a rate of 1°C / min, kept for 1 hour, and then heated to 350°C for 1 hour of roasting to obtain sulfated clinker. The amount of concentrated sulfuric acid added is based on the amount of H in sulfuric acid 2 SO 4 Al with fly ash 2 o 3 Add in a molar ratio of 3.5:1; mix the sulfated clinker with an appropriate amount of pulverized coal evenly, the amount of pulverized coal added is adjusted according to the alumina content in the fly ash and the amount of residual carbon in the fly ash, and then at 750°C Reduced roasting for 15 minutes to obtain reduced calcine; mixed and slurried the reduced calcine with sodium carbonate solution at 50°C for 60 minutes, filtered to obtain pretreated calcine; pretreated calcine with sodium hydroxide concentration of 150g / L The lye is leached at 100°C for 1 hour, filtered to obtain a sodium...

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Abstract

The invention discloses a fly ash carbonate solution pre-treatment and alumina extraction method, and belongs to the technical field of comprehensive utilization of fly ash. According to the fly ash carbonate solution pre-treatment and alumina extraction method, a mixture is prepared from fly ash and concentrated sulfuric acid or ammonium sulfate according to a certain ratio, and is calcined at atemperature of 200-500 DEG C to obtain a sulfated clinker, the sulfated clinker, fly ash and other reducing agents are subjected to rapid reducing calcination at a temperature of 650-900 DEG C to obtain reduced calcined sand, the reduced calcined sand is pre-treated with a carbonate solution, leaching is performed by using a low-temperature Bayer process, purification is performed with a sodium aluminate solution, seed precipitation is performed, and the metallurgical-grade alumina is prepared through aluminum hydroxide calcination. According to the present invention, the sulfur is removed from the fly ash or the re-calcined fly ash through the carbonate slurrying pre-treatment, such that the alkali consumption for the alumina production with the low-temperature Bayer process is reduced, the influence of the residual sulfur on the seed precipitation operation is reduced, and the method is especially suitable for the extraction of alumina from the circulating fluidized bed high aluminumfly ash; and the method has characteristics of short process, low energy consumption, low alkali consumption, high recovery rate, good alumina product quality and the like.

Description

technical field [0001] The invention belongs to the comprehensive utilization of fly ash, and relates to a method for producing alumina from fly ash, in particular to a method for pretreatment of fly ash carbonate solution and extraction of alumina. Background technique [0002] The coal combustion process produces a large amount of fly ash, except for a small part that is partially utilized for the production of cement building materials, and most of the fly ash is stockpiled, which not only occupies a large amount of land resources, but also seriously pollutes the environment. There are a large amount of high-aluminum coal in my country, and a large amount of high-alumina fly ash is produced during the combustion and power generation process. The aluminum content in the fly ash is as high as 40-60%, which has a high value for extracting aluminum. However, due to the low aluminum-silicon ratio in fly ash, the traditional alumina production process is difficult to adapt to f...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01F7/06
Inventor 蒋训雄范艳青蒋伟张登高汪胜东冯林永李达靳冉公赵峰刘巍白旭阳
Owner BEIJING GENERAL RES INST OF MINING & METALLURGY