CN1043032C

CN1043032C - Baeyer-synthesizing technology for processing bauxite

Info

Publication number: CN1043032C
Application number: CN95109061A
Authority: CN
Inventors: 艾孟井; 程宗浩; 刘子高
Original assignee: YIHUA INDUSTRIAL DESIGN INST GUIZHOU PROV
Current assignee: Guiyang resistant light metal design Co., Ltd.
Priority date: 1995-08-15
Filing date: 1995-08-15
Publication date: 1999-04-21
Anticipated expiration: 2015-08-15
Also published as: CN1117945A

Abstract

The present invention provides a technology for processing bauxite by a Bayer-synthesizing method mainly used for diasporic bauxite (the ratio of alumina to silica is more than 5). The Bayer method is used for processing bauxite to produce aluminum oxide, and red mud is uniformly mixed with lime and water by the Bayer method. The mixture is digested, agglomerated, steamed, calcined, ground and dissolved, and the residual dregs are calcined at low temperature and are ground to obtain an active Beta cement additive. The present invention has the advantages of reduced alkali consumption, enhanced overall yield of aluminum oxide, no environment pollution, etc. and waste can be changed into valuable. Active cement additive produced by adopting the technology of the present invention can enhance the early strength and the later strength of common cement.

Description

Handle the cryogenic calcining process of Bayer process red mud

The present invention relates to a kind of cryogenic calcining process of handling Bayer process red mud, belong to the field that light metal is smelted the comprehensive utilization bauxite resource.

At present, bayer's process is the technology of producing the preferential employing of aluminum oxide because of its investment and cost are low.Yet one ton of aluminum oxide of every production is about to discharge the Bayer process red mud about a ton, alkali is higher can not to be used to produce cement and Bayer process red mud is because of it contains, can only be as waste residue, being placed on red mud dump stores up, one meets wind and weather, soil and water source near environment around its red mud dust that flies upward will pollute, its alkali lye that leaks out will pollute are so Bayer process red mud is an evil of environmental protection.For this reason, people constantly study a kind of method that can effectively handle and utilize Bayer process red mud of seeking.In China, generally all adopt sintering process to handle Bayer process red mud now, but owing to sintering process flow process complexity, energy consumption height, and because the red mud alkalinity that sintering process is discharged is still high, still can not be utilized fully, also must set up the stockyard to stack, therefore environment still be caused certain harm.

The objective of the invention is to: a kind of cryogenic calcining process that mainly is suitable for handling the low Bayer process red mud of iron content is provided, has the gelling material of the compositions such as β-C2S of greater activity to utilize Bayer process red mud to produce, active additive as Portland cement, thereby utilize Bayer process red mud to produce useful material of construction product, reach the purpose of no waste sludge discharge.

The object of the present invention is achieved like this: Bayer process red mud and lime and water are mixed, digestion, briquetting, under the temperature of normal pressure and 85 ℃～100 ℃ steam-cured 4～10 hours then, again 550 ℃～950 ℃ temperature lower calcination 0.5～3 hour, with synthetic C2S and C12A7 mineral, it is levigate to calcine material, the yellow soda ash of discharging with the bayer's process system adds water and is made into levelling liquid, to align liquid and levigated material again and be 4～8 mixed by liquid-solid ratio, under 50 ℃～70 ℃ temperature, stir stripping, after 15 minutes slip separated and obtain solution and solid matter, solution and washings that separation is obtained return bayer's process system dilution again, two kinds of solution merge desiliconization, can satisfy the requirement of producing the high-purity hydrogen aluminum oxide, solid matter washed and after 1～4 hour, again it is milled down to 0.06mm～0.1mm, promptly get active β-C2S and early strong ferro-aluminate cement additive product at 700 ℃～950 ℃ temperature lower calcination; Red mud and lime blended ratio are determined by following method: the molecule number by composition Co (CaO) contained in the red mud, N (Na2O), S (SiO2), F (Fe2O3) and A (Al2O3) calculates the calcium oxide molecule number C that should add:

N/(F+A1)=1

C1/A2=1.4～1.7

A1+A2=A

C2/S=2

C=C1+C2-C0; When red mud mixes with lime, can add 0.5%～2.5% mineralizer and 1%～4% steam-cured qualified fragment and make crystal seed.

Owing to adopted above technical scheme, compare with existing sintering process technology, the present invention has the following advantages: 1, can slough the alkali in the red mud largely, the Na2O content of washing back residual residue is lower than about 1.2%, the technology alkaline consumption is reduced, and alkaline consumption is: Na2CO3＜70 kilogram/T-Al2O3; 2, fully reclaimed the aluminum oxide in the red mud (about more than 70%), improved the aluminum oxide total yield, thereby made aluminum oxide total yield＞91%; 3, be about 10 times of high temperature B-Dicalcium Phosphate (Feed Grade) by the hydration activity of the active β-C2S of SiO2 institute synthetic in the red mud (active beta-dicalcium silicate), it is a kind of new variety cement additire product, the free CaO of its product＜1%～3%, can before calcining, add materials such as flyash (also can when red mud and lime mixing, add flyash), aluminium hydroxide or Calcium Fluoride (Fluorspan), further reduce its free calcium oxide content; Therefore the raw material that the special slag of Baily also can send the cement mill to make to produce ordinary Portland cement has eliminated the pollution of waste residues such as red mud to environment.

Accompanying drawing 1 is a process flow diagram of the present invention.

Embodiments of the invention: bayer's process is processed the low diaspore type bauxite of iron content production Bayer red mud that aluminum oxide produced and the lime and the water of calculated amount mixes, digestion, briquetting, under normal pressure and 100 ℃ of temperature steam-cured 5 hours then, again 920 ℃ temperature lower calcination 2 hours, with mineral such as synthetic β C2S and C12A7, it is levigate to calcine material, the yellow soda ash of discharging with the bayer's process system adds water and is made into levelling liquid, to align liquid and levigated material is 5 by liquid-solid ratio (the Na2CO3 concentration of levelling liquid is 3%, NaOH is a small amount of) mixed, under 60 ℃ temperature, stir stripping, after 15 minutes slip separated and obtain solution and solid matter, solution and washings that separation is obtained return bayer's process system dilution again, two kinds of solution merge desiliconization, can satisfy the requirement of producing the high-purity hydrogen aluminum oxide, solid matter washed and at 920 ℃ temperature lower calcination after 2 hours, again it is milled down to 0.08mm, promptly getting active β C2S is the cement additire product of main component with early strong ferro-aluminate; Red mud and lime blended ratio are determined by following method: calculate the calcium oxide molecule number C that should add by the red mud composition:

N/(F+A1)=1

C1/A2=1.4～1.7

A1+A2=A

C2/S=2

C=C1+C2-C0; When red mud mixes with lime, can add the steam-cured qualified fragment that 1% CaF2 makes mineralizer and 2% and make crystal seed.

Active β-C2S the cement additire that adopts the present invention to produce, can improve the early strength and the later strength of ordinary Portland cement, as incorporation is 15%～25% o'clock, common 325# cement intensity can be brought up to the 425# cement intensity, and common 425# cement intensity can be brought up to the 525# cement intensity.

Claims

1, a kind of cryogenic calcining process of handling Bayer process red mud, it is characterized in that: Bayer process red mud and lime and water are mixed, digestion, briquetting, under the temperature of normal pressure and 85 ℃～100 ℃ steam-cured 4～10 hours then, again 550 ℃～950 ℃ temperature lower calcination 0.5～3 hour, with synthetic C2S and C12A7 mineral, it is levigate to calcine material, the yellow soda ash of discharging with the bayer's process system adds water and is made into levelling liquid, to align liquid and levigated material again and be 4～8 mixed by liquid-solid ratio, under 50 ℃～70 ℃ temperature, stir stripping, after 15 minutes slip separated and obtain solution and solid matter, solution and washings that separation is obtained return bayer's process system dilution again, two kinds of solution merge desiliconizations, can satisfy the requirement of producing the high-purity hydrogen aluminum oxide, solid matter are washed and at 700 ℃～950 ℃ temperature lower calcination after 1～4 hour, again it is milled down to 0.06mm～0.1mm, promptly gets active β-C2S and early strong ferro-aluminate cement additive product.

2, the cryogenic calcining process of processing Bayer process red mud according to claim 1 is characterized in that: red mud and lime blended ratio are determined by following method: the molecule number by composition Co (CaO) contained in the red mud, N (Na2O), S (SiO2), F (Fe2O3) and A (Al2O3) calculates the calcium oxide molecule number C that should add:

N/(F+A1)=1

C1/A2=1.4～1.7

A1+A2=A

C2/S=2

C=C1+C2-C0

3, the cryogenic calcining process of processing Bayer process red mud according to claim 1 is characterized in that: when red mud mixes with lime, can add 0.5%～2.5% mineralizer and 1%～4% steam-cured qualified fragment and make crystal seed.