CN101691294A - Process for preparing hydration-resistance high-calcium magnesia-calcium sand - Google Patents

Abstract

The invention belongs to a process for preparing magnesia-calcium sand for use in clean steel smelting. The process for preparing the hydration-resistance high-calcium magnesia-calcium sand comprises the following steps of: grinding highly purified dolomite until the size of the obtained fine powder is less than 10mum; putting the fine powder in a high-speed mixer, adding aqueous solution of polyvinyl alcohol in an amount which is 5 to 10 percent of the weight of the highly purified dolomite powder in the mixer, fully mixing the mixture and obtaining uniform wet powder, and pressing the wet powder to obtain finished blanks; burning the dry blanks obtained by drying the finished blanks at a temperature of between 1,650 and 1,700 DEG C to obtain the high-calcium magnesia-calcium sand. The method is characterized by improving sintering activity of the dolomite by mechanical activation, avoiding any additional sintering auxiliary agent, preparing the high-calcium magnesia-calcium sand in high density by the one-step calcining at a lower temperature, effectively lowering production cost, simplifying production process and ensuring purity of the magnesia-calcium sand.

Description

A kind of preparation technology of hydration-resistance high-calcium magnesia-calcium sand

Technical field

The invention belongs to a kind of Clean Steel and smelt the preparation technology who uses calcium magnesia sand, particularly relate to a kind of preparation technology of hydration-resistance high-calcium magnesia-calcium sand.

Background technology

According to the development strategy that China is changed to iron and steel power by big steel country, China will greatly develop high clean elaboration steel from now on.Produce Clean Steel and require the refractory materials long service life, molten steel is not polluted, preferably also have the effect of purify hot metal.The magnesium calcium refractory materials that only contains free CaO that possesses these use propertieies simultaneously, and theoretical and experiment showed, that the magnesium calcium refractory materials of CaO content height (〉=50%) is better to the decontamination effect improving of molten steel.

Yet the aquation problem in production, storage and transportation is the especially bottleneck of calcium magnesia refractory materials popularization and application of restriction magnesium calcium refractory materials always, and anti-aquation also is the centre point of magnesium calcium refractory materials research always.

Improve the hydration resistance of magnesium calcium refractory materials, the most basic and most critical be the density that will improve calcium magnesia sand.For improving the density of calcium magnesia sand, West Europe is mainly by improving sintering temperature, promptly adopt the ultrahigh-temperature kiln to burn till calcium magnesia sand, as German LWB company natural rhombspar is calcined in the high temperature kiln more than 1900 ℃, it is lower to obtain CaO content and be about 56% calcium magnesia sand activity, hydration resistance is preferably arranged, and be about 56% magnesia-calcium brick as feedstock production CaO, with the polyethylene film vacuum packaging, suppressed the aquation of magnesium calcium material preferably.Domestic because the restriction of ultrahigh-temperature kiln, do not possess ultrahigh-temperature agglomerating condition, the main two step calcination methods that adopt promptly are pressed into waste base with soft burnt lime stone, magnesite or light dolomite, burn till through 1600～1700 ℃ again, also improved the hydration resistance of calcium magnesia sand to a certain extent.Yet the energy consumption of two-step sintering method is higher, and operational condition extreme difference when using on a large scale easily causes the pollution to environment.The density that improves synthetic magnesia-calcium clinker by the interpolation sintering aid also is the method for current extensive employing, but sintering aid finally still will be to the especially slag resistance generation influence in various degree of high-temperature behavior of magnesia-calcium brick.Therefore be necessary in conjunction with China's national situation, explore new synthesis technique, prepare high purity, high-compactness, high calcium magnesia brick that hydration resistance is good.

Patent of invention " a kind of calcium-magnesium clinker of hydration resistance and production method thereof the " (patent No.: 96109507.5) announced a kind of hydration resistance calcium-magnesium clinker and production method thereof.This invention is taked to add the method promotion dolomite mineral of a small amount of CeO2 and sintering aids such as ferric oxide or iron scale or the sintering of light dolomite hydrate, magnesite or light-calcined magnesite hydrate, with the preparation calcium-magnesium clinker.

Patent of invention " the high temperature oil shaft furnace is calcined high-purity Mg-Ca synthesized sand and production technique thereof the " (patent No.: 99112638.6) disclose a kind of high temperature oil shaft furnace and calcined high-purity Mg-Ca synthesized sand and production technique thereof.The synthetic high-purity calcium magnesite of three steps calcining is adopted in this invention.

Patent of invention " a kind of preparation method of calcium-magnesium clinker " (patent No. 200610047355.1).This invention is a raw material with magnesite and limestone mine, makes calcium-magnesium clinker by 800～1000 ℃ of light-burned, coolings, aquation, ball milling wet mixing, filtration, 30～60 ℃ of carbonatings, drying, moulding, 1600～1900 ℃ of calcining procesies.

Patent of invention " a kind of preparation method of the compact alkaline magnesium-calcium synthetic material " (patent No.: 200810231514.2).It is main raw material that this method is selected natural magnesium rhombspar, magnesite clinker fine powder and lime fine powder for use, makes sintering aid with three yttrium oxide, burns till synthetic under 1600-1700 ℃ of temperature.

Patent of invention " a kind of method for preparing the clinker dolomite of the high temperature resistant waterproofization " (patent No.: 200710307215.8).This invention is a raw material with the unprocessed dolomite ore, adds sintering aids such as SiO2, P2O5, CaF2, CeO2, Fe2O3 and TiO2, through two steps calcining preparation clinker dolomite.

Summary of the invention

At existing technological deficiency of producing calcium magnesia sand, the invention provides a kind of preparation technology of hydration-resistance high-calcium magnesia-calcium sand, make that the high calcium magnesia brick of this prepared has that production cost is low, high-compactness, characteristics that hydration resistance is good.

The present invention is achieved through the following technical solutions above-mentioned purpose:

A kind of preparation technology of hydration-resistance high-calcium magnesia-calcium sand is characterized in that this technology comprises the steps:

(1), with the abundant fine grinding of high-purity rhombspar, powder particle size is less than 10um;

(2), fine powder that step (1) is obtained inserts in the high speed muller, adds the polyvinyl alcohol water solution that mass ratio is high-purity ground dolomite 5～10%, fully mixes, and obtains not having the even wet-milling of dry powder;

(3), the wet-milling that step (2) is obtained is pressed into base;

(4), with the wet base that step (3) obtains, seasoning 24～48 hours was gone into 120～140 ℃ of drying shed dryings 20～30 hours then;

(5), dry body that step (4) is obtained puts into kiln and fires, firing temperature is 1650～1700 ℃, is incubated 4～8 hours, obtains high calcium magnesia brick.

The characteristics of the inventive method are to utilize mechanical activation to improve the sintering activity of rhombspar, need not to add any sintering aid that adds, under lower temperature, can make the high calcium magnesia brick of high-compactness by one-step calcination, both reduced production cost effectively, simplify production technique, guaranteed the purity of calcium magnesia sand again.With the calcium magnesia sand of the inventive method preparation, free CaO content is up to 55～59%, volume density 〉=3.35g/cm3, and apparent porosity≤0.5%, hydration resistance is fabulous, can deposit the long period in atmosphere.

Embodiment

The present invention will be further described below in conjunction with example, but be not limited thereto.

Among the embodiment, magnesium carbide adds carbide of calcium＞99% in high-purity rhombspar.

Embodiment 1:

(1), with the abundant fine grinding of high-purity rhombspar, powder particle size is less than 10um;

(2), fine powder that step (1) is obtained inserts in the high speed muller, adds the polyvinyl alcohol water solution that mass ratio is high-purity ground dolomite 5～10%, fully mixes, and obtains not having the even wet-milling of dry powder;

(3), the wet-milling that step (2) is obtained is pressed into base;

(4), wet base that step (3) is obtained, seasoning 24 hours was gone into 120 ℃ of drying sheds dry 30 hours then;

(5), dry body that step (4) is obtained puts into kiln and fires, firing temperature is 1650 ℃, is incubated 8 hours, promptly gets high calcium magnesia brick.

Embodiment 2:

(1), with the abundant fine grinding of high-purity rhombspar, powder particle size is less than 10um;

(2), fine powder that step (1) is obtained inserts in the high speed muller, adds the polyvinyl alcohol water solution that mass ratio is high-purity ground dolomite 5～10%, fully mixes, and obtains not having the even wet-milling of dry powder;

(3), the wet-milling that step (2) is obtained is pressed into base;

(4), wet base that step (3) is obtained, seasoning 36 hours was gone into 130 ℃ of drying sheds dry 25 hours then;

(5), dry body that step (4) is obtained puts into kiln and fires, firing temperature is 1680 ℃, is incubated 6 hours, promptly gets high calcium magnesia brick.

Embodiment 3:

(1), with the abundant fine grinding of high-purity rhombspar, powder particle size is less than 10um;

(2), fine powder that step (1) is obtained inserts in the high speed muller, adds the polyvinyl alcohol water solution that mass ratio is high-purity ground dolomite 5～10%, fully mixes, and obtains not having the even wet-milling of dry powder;

(3), the wet-milling that step (2) is obtained is pressed into base;

(4), wet base that step (3) is obtained, seasoning 48 hours was gone into 140 ℃ of drying sheds dry 20 hours then;

(5), dry body that step (4) is obtained puts into kiln and fires, firing temperature is 1700 ℃, is incubated 4 hours, promptly gets high calcium magnesia brick.

Claims (1)

1. the preparation technology of a hydration-resistance high-calcium magnesia-calcium sand is characterized in that described technology comprises the steps:

(1), with the abundant fine grinding of high-purity rhombspar, powder particle size is less than 10um;

(2), fine powder that step (1) is obtained inserts in the high speed muller, adds the polyvinyl alcohol water solution that mass ratio is high-purity ground dolomite 5～10%, fully mixes, and obtains not having the even wet-milling of dry powder;

(3), the wet-milling that step (2) is obtained is pressed into base;

(4), with the wet base that step (3) obtains, seasoning 24～48 hours was gone into 120～140 ℃ of drying shed dryings 20～30 hours then;

(5), dry body that step (4) is obtained puts into kiln and fires, firing temperature is 1650～1700 ℃, is incubated 4～8 hours, obtains high calcium magnesia brick.