CN102515590B - Process for producing sulphoaluminate cement by proportioning for direct slurry of red mud - Google Patents

Abstract

The invention relates to a process for producing sulphoaluminate cement by proportioning for the direct slurry of red mud, comprising the following steps of: adding raw slurry red mud in calcium oxide to hydrate, so as to obtain an alkaline-containing slurry; adding the alkaline-containing slurry in desulfurized gypsum to proportion; testing the ingredients of the slurry and correcting the ingredient by a correction material; press-filtering and drying the slurry to obtain a solid substance in which the mass of CaO occupies 43-49%, the mass of SiO2 occupies 12-20%, the mass of Al2O3 occupies 10-22%, the mass of Fe2O3 occupies 10-22% and the mass of SO3 occupies 3-12%, setting an alkalinity coefficient C in the slurry to be less than 0.921 and setting an aluminium-sulphur ratio P to be less than 3; and press-filtering and dehydrating the proportioned slurry, airing or drying the press-filtered solid substance, and then calcining to product cement. Because of completely using waste resources as main raw materials, the process disclosed by the invention is high in waste absorption capacity and capable of directly omitting grinding system for raw material, finishing homogenization for raw material in proportioning pool, and being used for production for clinker after press-filtering.

Description

A kind of technique of producing sulphoaluminate cement by proportioning for direct slurry of red mud

Technical field

The present invention relates to a kind of technique of utilizing red mud to produce the processing method, particularly a kind of producing sulphoaluminate cement by proportioning for direct slurry of red mud of aluminosulfate cement.

Background method

Red mud is large trade waste that alumina producing enterprise produces, and quantity discharged is huge, and 1 ton of aluminum oxide of every production can produce 0.8-1.5 ton red mud, and for example, only the red mud quantity discharged in the whole nation in 2010 just reaches nearly 5,000 ten thousand tons.Because red mud has the features such as high alkalinity, high humidity, high fineness, to utilize extremely difficultly, utilization ratio less than 10% causes bulk deposition, and accumulative total volume of cargo in storage in the whole nation has reached tens tons at present.Storing up of red mud, the stockyard construction investment is large on the one hand, takies a large amount of soils, and air, the hydrology and the edatope of airborne dust and alkaline severe contamination locality are destroyed ecology on the one hand, are detrimental to health.In the policies such as country's " 12 " science and technology development planning, metal tailings comprehensive utilization ad hoc planning, the red mud comprehensive utilization is all pointed out by emphasis.Current, the magma red mud has small-scale trial and application at aspects such as making roadbed, brick and tile, cement raw material, some small business choose at metals such as carrying out iron, titanium because income drives, but these effective digestion abilities to red mud are all very limited, for example make the cement raw material usage ratio usually 5% once, therefore utilize technology to remain to be broken through.

High (the Na of alkalinity ₂O accounts for 5-10%) be the major obstacle that the restriction Bayer process red mud utilizes, adhere to the alkali except part, mainly be the combined alkali that exists with the sodium white residue, be difficult to direct removal.In the process of balance cost of disposal, environmental cost and economic return, some large-scale Alumina Enterprises begin to pay attention to the dealkalize processing of red mud, normal pressure or pressure oxidation calcium aquation method are successful dealkalize technique, are that the sodium white residue in the lower red mud of hydrothermal condition becomes calcium-silicon slag.Red mud after the dealkalize has the potentiality of extensive utilization.The cost of red mud dealkalization is higher, if can not all effectively utilize the red mud after the dealkalize, enterprise does not then carry out the fundamental driving force that dealkalize is processed.Current dealkalize red mud is produced the add-on of red mud in the cement method, and general silicate cement is below 50%, and aluminosulfate cement can reach 70%.Disclose a kind of method of utilizing red mud and desulfurated plaster to prepare cement such as patent CN 101891406A, batching by weight percentage is as follows: the red mud 50～70% behind the iron, desulfurated plaster 5～15%, Wingdale 20～40% are selected in dealkalize; To prepare burden through behind the grinding, and in kiln, calcine and form.But, be mostly in the utilization of prior art the dealkalize red mud is used for conventional cement production process, conventional raw meal proportioning, and must carry out raw grinding, and grinding energy can not be avoided, and technical process is long, takes up room large, and the production time is long.

Summary of the invention

The objective of the invention is to overcome above-mentioned deficiency, a kind of technique of producing sulphoaluminate cement by proportioning for direct slurry of red mud is provided, this kind technique can connect as one the dealkalize of red mud and aluminosulfate cement production, need not the raw grinding system, greatly improved again the utilization ratio of red mud, reduce Re-pollution, reduce cost.

The technical scheme that the present invention takes is:

A kind of technique of utilizing producing sulphoaluminate cement by proportioning for direct slurry of red mud comprises that step is as follows:

(1) the magma red mud is added calcium oxide aquation, CaO and Na ₂The O mass ratio is controlled at 3～4: 1, and hydration time 2～4 hours must contain the alkali slurries;

(2) will contain the alkali slurries and move into dosing chamber, and add the desulfurated plaster batching, the test slurry content is also carried out composition with the correction material and is proofreaied and correct, and makes slurries account for 43～49% (wt%), SiO through CaO in the solid matter of press filtration, oven dry gained ₂Account for 12～20% (wt%), Al ₂O ₃Account for 10～22% (wt%), Fe ₂O ₃Account for 10～22% (wt%), SO ₃Account for 3～12% (wt%), and make that basicity factor C satisfies between 0.92～1 in the slurries, aluminium-sulfur ratio P＜3; Wherein

$C=\frac{\mathrm{CaO}-0.70\×{\mathrm{TiO}}_2}{0.73\×({\mathrm{Al}}_2{O}_3-0.64\×{\mathrm{Fe}}_2{O}_3)+1.40\×{\mathrm{Fe}}_2{O}_3+1.87\×{\mathrm{SiO}}_2}$

$P=\frac{{\mathrm{Al}}_2{O}_3-0.64\×{\mathrm{Fe}}_2{O}_3}{{\mathrm{SO}}_3}$

CaO, SiO in the formula ₂, Al ₂O ₃, Fe ₂O ₃, TiO ₂, SO ₃Be respectively the shared weight percent of corresponding chemical composition;

(3) slurries that step (2) prepared carry out filter-press dehydration, the recycle of alkali liquor (can be used further to alumina producing) that contains NaOH, solid matter after the press filtration is through drying or drying, moisture enters preheater or calcines directly into cement rotary kiln to make cement when 0～20% (wt%), firing temperature is 1250～1300 ℃, and calcination time is 30～60 minutes.Slurries in the above-mentioned processing step (2) in through press filtration, the oven dry after solid matter, the consumption of desulfurated plaster accounts for 5～15% (wt%), proofread and correct material and account for 0～20% (wt%), the consumption of dealkalize red mud (refer to contain alkali slurries part after filtration, the solid matter after the oven dry) accounts for 75～90% (wt%).Described correction material is selected from one or more in lime, carbide slag, the flyash.

The cement clinker that the present invention burns till is with calcium sulphoaluminate (3CaO3Al ₂O ₃CaSO ₄) and Dicalcium Phosphate (Feed Grade) (2CaOSiO ₂) and iron phase be the essential mineral phase, proportion is respectively 15～45%, 35～65% and 10～30%.

Products obtained therefrom of the present invention belongs to the aluminosulfate cement of high silicon high iron type, and the characteristics of high silicon high iron are greatly expanded the adaptability to raw materials of this technology, and the waste resource that various iron levels are higher all might use by vast scale, is the desirable approach that realizes the solid waste resource utilization.And, high silicon high iron and belong to the characteristics of sulplo-aluminate type so that the equal ideal comparatively of the early stage and later stage mechanical property of cement products of the present invention, calcium sulphoaluminate provides preferably early strength, Dicalcium Phosphate (Feed Grade) is so that later strength can sustainable growth, so product has the characteristics of aluminosulfate cement and silicate cement concurrently.

Replace owing to will add a certain amount of calcium in the dealkalize process, coupling and the cement composition of the elements such as calcium, silicon, aluminium are very approaching in the dealkalize red mud, are fabulous cement raw materials.In view of the dealkalize red mud higher alumina silica ratio is arranged usually again, then very suitable and desulfurated plaster is used in conjunction with the production aluminosulfate cement.The present invention proposes the composite technology of a kind of dealkalize processing and aluminosulfate cement production, both can realize the at high proportion utilization of dealkalize red mud, obtains high performance aluminosulfate cement product, can also reclaim the Na in the red mud ₂O makes it to be reused for alumina producing.

Advantage of the present invention is to utilize waste resource as main raw material fully, eats useless amount greatly, and cost is low, and energy consumption is low, and cement performance is good, has significant economic benefit and environmental benefit.In the present invention, the consumption of dealkalize red mud can reach 75～90%, and the consumption of desulfurated plaster is 5～15%, and correction material is 0～20%.Employed main raw material red mud and desulfurated plaster and correction material flyash and carbide slag are the waste resource of enormous amount, so raw materials cost is cheap.The optimum burning temperature-forming of present technique is 1250～1300 ℃, and than 1450 ℃ of silicate cement low about 200 ℃, and because iron level is high, than low about 50 ℃ of general aluminosulfate cement firing temperature, energy-saving potential is large.In addition, owing to red mud, desulfurated plaster, flyash, carbide slag all have enough fineness, can directly save the raw grinding system, can finish the raw material homogenizing in the dosing chamber, namely can be used for grog production after the press filtration.Press filtration itself namely is the part of red mud dealkalization technique, is not additional step, and the alkali lye that is press-filtered out is recyclable and be used further to alumina producing, can realize the water cycle processing.The present invention can all utilize the dealkalize red mud, can not produce in addition waste residue, and without sewage discharge does not almost have environmental pollution.Cement products belongs to aluminosulfate cement, has the premium propertiess such as early strong, high-strength, anticorrosive.

Description of drawings

Fig. 1 is process flow sheet of the present invention;

Fig. 2 is the X ray diffracting spectrum of the cement clinker that burns till of embodiment 1;

Wherein, A is calcium sulphoaluminate, and B is Dicalcium Phosphate (Feed Grade), and C, D are iron phase.

Embodiment

Further specify the present invention below in conjunction with embodiment.

Embodiment 1:

The magma red mud is added the calcium oxide aquation, must contain the alkali slurries, add desulfurated plaster, carbide slag and flyash and prepare burden, in the solid matter after process press filtration, the oven dry, the dealkalize red mud accounts for 80.5%, and desulfurated plaster accounts for 8.5%, carbide slag accounts for 8.4%, and flyash accounts for 2.6%.Batching slurries moisture after press filtration is 43% (wt%), dries through nature, and moisture is down to 18% (wt%).Directly be conveyed in the hollow kiln and calcine, firing temperature is 1250 ℃, and calcination time is 60 minutes.Accompanying drawing 2 is the X ray diffracting spectrum of the cement clinker that burns till, and main phase is calcium sulphoaluminate, Dicalcium Phosphate (Feed Grade) and iron phase, belongs to high silicon high iron type aluminosulfate cement.Through cement standard cement mortar strength test, 3 days and 28 days ultimate compression strength are respectively 28.5Mpa and 56Mpa.

Embodiment 2:

The magma red mud is added the calcium oxide aquation, must contain the alkali slurries, add desulfurated plaster and prepare burden, in the solid matter after process press filtration, the oven dry, the dealkalize red mud accounts for 89.5%, and desulfurated plaster accounts for 9.5%.Batching slurries moisture after press filtration is 43% (wt%), dries through nature, and moisture is down to 18% (wt%).Directly be conveyed in the hollow kiln and calcine, firing temperature is 1250 ℃, and calcination time is 60 minutes.Through cement standard cement mortar strength test (GB/T 17671-1999), 3 days and 28 days ultimate compression strength are respectively 26.5Mpa and 52.4Mpa.

Embodiment 3:

The magma red mud is added the calcium oxide aquation, must contain the alkali slurries, add desulfurated plaster, carbide slag and flyash and prepare burden, in the solid matter after process press filtration, the oven dry, the dealkalize red mud accounts for 80.5%, and desulfurated plaster accounts for 8.5%, carbide slag accounts for 8.4%, and flyash accounts for 2.6%.Batching slurries moisture after press filtration is 43% (wt%), and through oven dry, moisture is down to 3% (wt%).Directly be conveyed in the hollow kiln and calcine, firing temperature is 1270 ℃, and calcination time is 40 minutes.Through cement standard cement mortar strength test, 3 days and 28 days ultimate compression strength are respectively 31.4Mpa and 60.2Mpa.

As mentioned above, embodiments of the invention are explained, but as long as not breaking away from fact inventive point of the present invention and effect can have a lot of distortion, this will be readily apparent to persons skilled in the art.Therefore, such variation also all is included within protection scope of the present invention.

Claims (2)

1. technique of utilizing producing sulphoaluminate cement by proportioning for direct slurry of red mud comprises that step is as follows:

(1) the magma red mud is added calcium oxide aquation, Na in CaO and the magma red mud ₂The O mass ratio is controlled at 3～4:1, and hydration time 2～4 hours must contain the alkali slurries;

(2) will contain the alkali slurries and move into dosing chamber, and add the desulfurated plaster batching, the test slurry content is also carried out composition with the correction material and is proofreaied and correct, and makes slurries account for 43～49%, SiO through CaO quality in the solid matter of press filtration, oven dry gained ₂Quality accounts for 12～20%, Al ₂O ₃Quality accounts for 10～22%, Fe ₂O ₃Quality accounts for 10～22%, SO ₃Quality accounts for 3～12%, and makes that basicity factor C satisfies between 0.92～1 in the slurries, aluminium-sulfur ratio P＜3; Wherein

$C=\frac{\mathrm{CaO}-0.7.\×{\mathrm{TiO}}_2}{0.73\×({\mathrm{Al}}_2{O}_3-0.64\×{\mathrm{Fe}}_2{O}_3)+1.40\×{\mathrm{Fe}}_2{O}_3+1.87\×{\mathrm{SiO}}_2}$

$P=\frac{{\mathrm{Al}}_2{O}_3-0.64\×{\mathrm{Fe}}_2{O}_3}{{\mathrm{SO}}_3}$

CaO, SiO in the formula ₂, Al ₂O ₃, Fe ₂O ₃, TiO ₂, SO ₃Be respectively the shared mass percent of corresponding chemical composition; Described correction material is selected from one or more in lime, carbide slag, the flyash; Slurries are in through the solid matter after press filtration, the oven dry, and the consumption of desulfurated plaster accounts for 5～15%, proofreaies and correct material and accounts for 0～20%, and the consumption of dealkalize red mud accounts for 75～90%;

(3) slurries that step (2) prepared carry out filter-press dehydration, contain the recycle of alkali liquor of NaOH, and the solid matter after the press filtration makes cement through drying or dry, calcining.

2. the technique of utilizing producing sulphoaluminate cement by proportioning for direct slurry of red mud according to claim 1 is characterized in that, calcining temperature is 1250 ~ 1300 ℃, and calcination time is 30 ~ 60 minutes.