CN1408666A

CN1408666A - process for producing magnesium oxide from waste magnesite ore

Info

Publication number: CN1408666A
Application number: CN 01128222
Authority: CN
Inventors: 吕佳成
Original assignee: SHENGLI EMERY WHEEL FACTORY SUJIATUN DISTRICT SHENYANG CITY
Current assignee: SHENGLI EMERY WHEEL FACTORY SUJIATUN DISTRICT SHENYANG CITY
Priority date: 2001-09-29
Filing date: 2001-09-29
Publication date: 2003-04-09

Abstract

The present invention relates to production process of magnesia from waste magnesite ore. The magnesite ore of 35-44 % purity is crushed to 100-300 mm size and baked in a reverberator at 700-850 deg.c to obtain light burned magnesia, and the light burned magnesia is produced into light magnesia through ball milling, 120-mesh sieving, adding water to digest, mixing with introduced Co2 in the carbonating pressure tank to light acid while stirring, filtering, purifying, heating with same to 80-100 deg.c to decompose and deposit for separation, filtering to eliminate water, stoving and sintering at 800-900 deg.c and other steps. The said process can produce various magnesia products with waste magnesite ore.

Description

Method for producing magnesium oxide from waste magnesite ore

Technical Field

The invention relates to a method for obtaining magnesium oxide by calcining magnesite ore, in particular to a method for producing high-purity magnesium oxide by using waste magnesite ore.

Background

The main component of magnesite ore is MgCO₃And also contains unequal amounts of Fe₂O₃·Al₂O₃With SiO₂And the like. Pure magnesite concentrate contains 47.8% of MgO, but the concentrate is not ubiquitous, and most magnesite contains MgCO₃About 90% (MgO-42%). MgCO₃More than 95% of the ore is very small and therefore magnesite calcined directly from magnesite contains a large amount of impurities, which is very disadvantageous. In order to obtain high-purity magnesium oxide and magnesite, a manual synthesis technology is adopted at home and abroad, namely high-purity magnesium carbonate is firstly synthesized, then the magnesium oxide is lightly calcined, and finally the magnesite is calcined at high temperature,its purity can be greater than 99.5%, and in the course of mining magnesite in China, firstly, the special grade or first grade rich ore (MgCO) is screened out₃More than 90 percent), and the rest secondary and tertiary ores are discarded as waste products, but the discarded ores also contain 26 to 40 percent of MgO, and the MgO can be purified and utilized to produce high-purity magnesium oxide. It is significant to save resources, protect resources and control environmental pollution. Because of direct calcination, high-grade magnesite is mostly selected, and secondary and tertiary middle and low grade ores with lower magnesium content are discarded, so that great waste of resources is caused. Simultaneously occupies land, pollutes environment, and does not accord with sustainable development strategy and the requirement of clean production process.

Disclosure of Invention

The invention aims to provide a method for producing high-purity magnesium oxide from waste magnesite.

The production method comprises the steps of crushing magnesite ore with the purity of 35-44% into 100-300 mm, burning the magnesite ore to 700-850 ℃ by using a reverberatory furnace to obtain light-burned magnesium, cooling, ball-milling, sieving by using a 120-mesh sieve, adding water, digesting for 1-4 hours, pumping the magnesium into a carbonization pressure tank, adding water, keeping the temperature at 20-30 ℃, and introducing CO with the concentration of 30-40%₂Stirring the gas for 40 minutes, checking until the gas is slightly acidic, stopping ventilation and stirring, filtering, adding a purifying agent into a storage tank, purifying, finely filtering, and decomposing and precipitating through hot steam at the temperature of 80-100 ℃; and filtering to remove the aqueous solution, precipitating, drying, and sintering to 800-900 ℃ to obtain the light magnesium oxide.

The method provided by the invention can produce high-purity magnesium carbonate, active magnesium oxide, light magnesium oxide, magnesium hydroxide, high-purity dead-burned magnesia and high-purity magnesium oxide from waste magnesite (high-grade ore is certainly better). The fused magnesite obtained by the method is a heavy basic raw material of an electrothermal original device used in the household appliance industry in China, is low-iron industrial magnesite, and can be mixed with organic and inorganic materials to produce high-temperature modified magnesium powder, so that the household appliance industry of China can be greatly improved on electrothermal products, and the fused magnesite is comparable to similar products of America and Japan.

Drawings

The attached drawing is a process flow chart of the invention.

Detailed Description

The main equipment is as follows:

1. lime kiln: the capacity is determined according to the production scale and the MgO content of the raw material

The temperature of a sintering zone is 700-800 DEG C

With dust remover and CO₂Purifying device

2. A carbonization tank: volume 20m³Yield 400 KgMgO/time

The height is 7m, and the stirring speed is 70 r/min

Diameter of 3m, with pressure gauge and air release valve

Pressure test of 1MPa and CO₂The concentration is 30-40%

3. Magnesium carbonate filtration: 400 tons of filter cake with 80% water content is filtered every day

4. Light burning equipment: the rated service temperature is 1300 DEG C

Light burning 1.5 tons in one time (2 hours)

5. A high-temperature calcinator: the control is accurate to +/-5 ℃, and the use temperature is 1550-1650 ℃. At each step of production, a different chemical reaction takes place:

1. sintering magnesite: MgCO is mixed with₃To become MgO

2. Digestion: hydration of MgO to Mg (OH)₂

3. Carbonizing: MgO and Mg (OH)₂With CO₂Reaction to produce liquid phase magnesium bicarbonate

4. Pyrolysis: mg (HCO)₃)₂Heating to decompose and separate out precipitate

5. Light burning: MgCO₃Loss of CO₂To become MgO

6. And (3) calcining: MgO 'dead burning' has no chemical activity.

Examples

Crushing magnesite ore to 200mm, burning in a reverberatory furnace at 800 deg.C for 2 hr to obtain light-burned magnesium, cooling, taking out, adding water, stirring, and passing throughBall-milling, sieving with 120 mesh sieve, adding water, digesting for 3 hr, pumping into carbonization pressure tank at solid-liquid ratio of 1: 25, adding water, maintaining the temperature of reaction tank at 20 deg.C, and introducing 30-40% CO₂And (4) continuously stirring the gas, checking the pH value of the reaction tank after 40 minutes, and stopping ventilation and stirring when the reaction tank is slightly acidic. Filtering the slurry in the tank by a scraper filter, pumping the slurry into a storage tank, adding a purifying agent for purification, then finely filtering, enabling the aqueous solution to flow into a pyrolysis tank, introducing superheated steam, heating to 80-100 ℃, and then decomposing the solution and precipitating out. Filtering with plate-and-frame filter press to remove water solution (for recycling), drying the precipitate at about 150 deg.C, sintering to 800-900 deg.C, and controlling heating time to make CO₂And (4) completely decomposing to produce light magnesium oxide, and placing the light magnesium oxide in a drying place for cooling, and then quickly sealing and packaging to obtain a MgO finished product.

The main technologicalparameters are as follows:

1. sintering magnesite at a temperature: 700-850 ℃;

2. granularity of mineral powder: passing through a 120 mesh screen, preferably a 200 mesh screen;

3. purifying agent: magnesium carbonate in right amount;

4. carbonization time: 40-50 minutes; pressure: 2.5 to 5.5 MPa; temperature: 20-30 ℃;

5. pyrolysis temperature: 80-100 ℃;

6. drying temperature: 100-150 ℃;

7. light burning temperature: 800-900 ℃;

8. crushing fineness: is smaller than 320 meshes.

Comparative example

The purity of the magnesium oxide produced by the method can reach 99.5-99.8%, and the magnesium oxide does not contain halogen elements; the purity of magnesium oxide produced by seawater for foreign production can reach as high as 99.5%, and the magnesium oxide contains halogen elements.

Claims

1. The method for producing magnesium oxide from waste magnesite ore is characterized in that the magnesite ore with the purity of 35-44% is crushed to the granularity of 100-300 mm, the crushed magnesite ore is burnt to 700-850 ℃ by a reverberatory furnace to obtain light burnt magnesium, the light burnt magnesium is cooled, ball-milled and sieved by a 120-mesh sieve, the light burnt magnesium is digested for 1-4 hours by adding water, then the mixture is pumped into a carbonization pressure tank, the temperature of the mixture is kept at 20-30 ℃, and CO with the concentration of 30-40% is introduced₂Stirring the gas for 40 minutes, checking until the gas is slightly acidic, stopping ventilation and stirring, filtering, adding apurifying agent into a storage tank, purifying, finely filtering, and decomposing and precipitating through hot steam at the temperature of 80-100 ℃; and filtering to remove the aqueous solution, precipitating, drying, and sintering to 800-900 ℃ to obtain the light magnesium oxide.

2. The method of claim 1, wherein said digestion with water is followed by a solids to liquids ratio of 1: 25.