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A process for producing high-purity magnesium oxide from dolomite

A process method and technology of magnesia, applied in directions such as magnesia, can solve the problem of difficult separation of calcium and magnesium, and achieve the effects of simple process, abundant raw materials and low production cost

Inactive Publication Date: 2011-12-14
NANJING UNIV OF AERONAUTICS & ASTRONAUTICS +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] In order to solve the technical problem that calcium and magnesium are difficult to completely separate in the dolomite carbonization method, the present invention provides a process for producing high-purity magnesium oxide from dolomite, which solves the problem of calcium and magnesium by adding oxalic acid or soluble oxalate during digestion. Difficult to separate, improve the yield of magnesium oxide produced by dolomite carbonization

Method used

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  • A process for producing high-purity magnesium oxide from dolomite
  • A process for producing high-purity magnesium oxide from dolomite
  • A process for producing high-purity magnesium oxide from dolomite

Examples

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Embodiment 1

[0034] Example 1: The chemical composition of dolomite is MgO content 20.96%, CaO content 30.06%, broken to 2~5cm. Calcined at 900°C for 3h to obtain calcined white. The calcined white is mixed according to the mass ratio of water: calcined white is 50:1, heated and stirred to 60° C., kept for 1 hour for digestion, and the emulsion is obtained. The emulsion is passed through a 60-mesh sieve to obtain refined magnesium emulsion. After cooling to room temperature, CO 2 , CO 2 The flow rate is 0.5L / min, and the pH value of the carbonization system is tracked and tested. When the carbonization system is at pH=8.5, add ammonium oxalate to make the concentration of oxalate in the system 0.002mol / L, continue carbonization to pH=6.5, and stop carbonization. The carbonized system is separated from solid to liquid, the solid phase is light calcium carbonate, and the liquid phase is heavy magnesium water. The obtained heavy magnesium water is pyrolyzed at 95°C for 2 hours, solid-liq...

Embodiment 2

[0035] Example 2: The composition of dolomite is MgO content 20.96%, CaO content 30.06%, broken to 2~5cm. Calcined at 950°C for 2.5h to obtain calcined white. Mix calcined white according to the mass ratio of water: calcined white is 40:1, stir and heat to 70°C, heat-preserve and digest for 1.5h to obtain emulsion. The emulsion is passed through a 60-mesh sieve to obtain refined magnesium emulsion. After cooling to room temperature, CO 2 , CO 2The flow rate is 0.8L / min, and the pH value of the carbonization system is tracked and tested. When the carbonization system is at pH=9.0, add oxalic acid to make the concentration of oxalate in the system 0.005mol / L, continue carbonization to pH=6.8, and stop carbonization. The carbonized system is separated from solid to liquid, the solid phase is light calcium carbonate, and the liquid phase is heavy magnesium water. The obtained heavy magnesium water is pyrolyzed at 100°C for 2 hours, solid-liquid separation after cooling, and t...

Embodiment 3

[0036] Example 3: The composition of dolomite is MgO content 20.96%, CaO content 30.06%, broken to 2~5cm. Calcined at 1000°C for 2 hours to obtain calcined white. Mix calcined white according to water: calcined white = 60:1, stir and heat to 70°C, heat-preserve and digest for 2 hours to obtain emulsion. The emulsion is passed through a 60-mesh sieve to obtain refined magnesium emulsion. After cooling to room temperature, CO 2 , CO 2 The flow rate is 1L / min, and the pH value of the carbonization system is tracked and tested. When the carbonization system is at pH=9.0, add oxalic acid to make the concentration of oxalate in the system 0.008mol / L, continue carbonization to pH=6.5, and stop carbonization. The carbonized system is separated from solid to liquid, the solid phase is light calcium carbonate, and the liquid phase is heavy magnesium water. The obtained heavy magnesium water is pyrolyzed at 100°C for 2 hours, solid-liquid separation after cooling, and the solid phas...

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Abstract

The invention discloses a process for producing high purity magnesium oxide with dolomite, comprising the steps of: subjecting dolomite to fragmentation, calcination, digestion, filtration, carbonization, solid-liquid separation, pyrolysis, basic magnesium carbonate drying and basic magnesium carbonate calcination, thus obtaining high purity magnesium oxide with CaO content less than 0.2%, Fe content less than 0.01% and MgO content higher than 98%. The process is totally in accord with the technical requirements of HG / T2573-2006 "industrial lightweight magnesium oxide" for Class I and Class II high-class products. The invention puts forward an improving method for the digestion and carbonization processes during high purity magnesium oxide production from dolomite, thus raising the extraction rate of MgO from dolomite. By adding a certain amount of oxalic acid and soluble oxalate into the carbonization system, the technical problem that calcium and magnesium are difficult to be separated thoroughly in a dolomite carbonization method can be solved. The process of the invention has the characteristics of simple technology, easy control, high extraction rate of magnesium oxide and high purity product.

Description

[0001] technical field [0002] The invention relates to a process for mineral processing and utilization, in particular to a process for preparing high-purity magnesium oxide from dolomite. Background technique [0003] High-purity magnesia refers to light magnesia with MgO content higher than 98%, which is widely used in the fields of surface coating, papermaking, metallurgy, ceramics and refractory materials. The methods of producing high-purity magnesium oxide mainly include brine-limestone (dolomite) method, brine-ammonification method, brine-soda ash method, brine-ammonium bicarbonate method, dolomite-carbonization method, etc. The use of magnesium-rich ores (such as dolomite, magnesite, serpentine, etc.) to produce magnesium oxide products has broad development space because of its simple process, low cost, and easy industrial production. [0004] my country's dolomite resources are widely distributed, with reserves of 8.22 billion tons. The origins are all over the ...

Claims

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Application Information

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IPC IPC(8): C01F5/02
Inventor 余红发吴成友武金永董金美李颖
Owner NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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