CN101045947A - Alkali exciting and comprehensively utilizing process of iron-containing furnace dust - Google Patents

Abstract

The present invention is alkali exciting and comprehensively utilizing process of iron-containing furnace dust and has three technological methods, including alkali slag cement production, wet metallurgy and alkali solution concentration, fused for treating iron-containing furnace dust. By means of treating iron-containing furnace dust with hot alkali solution and solvent, iron-containing furnace dust is hydrated and gelled, and useful metal elements are dissolved into alkali solution for separation. The comprehensive utilization can obtain suspension of iron-containing furnace dust as the main product, which may be used as the gelatinizer for pelletizing iron concentrate powder, and side products, such as coarse zinc, zinc hydroxide, etc.

Description

Iron-containing furnace dust alkali excites comprehensive utilization method

The present invention relates to the comprehensive utilization of iron and steel enterprise's industrial waste.

In steel smelting procedure, contain a certain amount of solia particle in the high-temperature flue gas that various metallurgical furnaces are discharged, usually these solia particles are referred to as iron-containing furnace dust.The iron-containing furnace dust generation can reach pig iron output 2～3.2% and crude steel output 1.2～2.2%, be one of large industrial waste of each big steel factory.Because of the output form of dedusting (collection) method difference, iron-containing furnace dust also different.Generally, the wet dedusting gleanings is called ion dust mud contaning, with mud form output, and the water content height, dehydration has certain difficulty; The dry method dust gleanings is called iron content dirt ash, with dry ash form output (referring to table 1).

At present, mostly iron-containing furnace dust is mixed in the sintered material in the industry and recycled.Do like this, high-grade iron content dirt ash is fit to, also very convenient; And the ion dust mud contaning utilization has just had the trouble of draining; Low-grade iron content dirt ash is just more awkward, hesitates to discard, selected difficulty, the weary benefit used.

The iron content dirt ash comprehensive utilization that contains zinc (referring generally to TFe＜50%, ZnO＞3%) at ion dust mud contaning and low iron has the reality of certain difficulty, relating to the smart powder agglomeration of iron granulates to the actual demand of jelling agent, three technology methods such as alkali slag cement principle, hydrometallurgy and liquid caustic soda concentrate have been merged in the present invention, have proposed iron-containing furnace dust alkali and have excited comprehensive utilization method.Boil iron-containing furnace dust and solvation processing by alkali lye heat, excite the potential aquation gelling of iron-containing furnace dust, promote the useful metal element to dissolve in alkali lye and therefrom separation simultaneously.The comprehensive utilization product is that alkali excites solvation iron-containing furnace dust suspension, mainly the jelling agent of granulating as the smart powder agglomeration of iron; Byproduct can obtain crude zinc or zinc hydroxide etc.This method makes full use of and has brought into play iron-containing furnace dust three big technical characteristic and advantages, has satisfied the needs that utilization of resources maximization and comprehensive utilization cost reduce.The wet work of production whole process, alkali lye recycles, and does not have the puzzlement of smoke contamination, obnoxious flavour infringement.

1. the characteristic of iron-containing furnace dust

Iron-containing furnace dust is the submicron order powder body material of a kind of many metal enrichments, volcano grey matter.

1.1. iron-containing furnace dust is created on hot environment, belongs to the high-temperature aerosol component.Temperature in the various metallurgical furnaces: 1250 ℃ of sintering, 1450 ℃ in blast furnace, 1650 ℃ of converters, electric furnace＞1650 ℃.Turn under the usefulness at high temperature substrate, the chemical potential that iron-containing furnace dust is stored increases.From the thermodynamics aspect, except ferriferous oxide, all have potential volcano grey matter hydrated adhesive and coagulate performance in the iron-containing furnace dust, having can the hydrolysis of spontaneous generation aquation under the water participation.Visualize: moistening iron-containing furnace dust is stored up under field conditions (factors), all has exothermic phenomenon to take place, and their gellings lentamente, hardens into the calculus body of certain intensity.

1.2. the chemical ingredients of iron-containing furnace dust, has magnetic or weak magnetic based on ferriferous oxide; Next is admixture compositions such as flux, the relative enrichment of low melting point metal oxide compound (referring to table 1).These low melting point metal oxide compounds come from iron ore or other raw materials, at high temperature evaporation, condensation enrichment in flue dust.Comparatively speaking, the relative enrichment of sinter machine dedusting ash basic metal; Blast furnace gas mud (ash) except the carbon content height, the relative enrichment of heavy metal oxide such as plumbous zinc; Electric furnace dirt ash component complexity, directly relevant with steel scrap with the smelting steel grade.Generally, except the relative enrichment of heavy metal oxides such as plumbous zinc, other heavy metal element also is able to enrichment, and is relatively large to environmental hazard.

Iron-containing furnace dust is kind and respective sample chemical ingredients composition bibliography (%) table 1 roughly

1.3. the iron-containing furnace dust grain diameter is superfine, particle size range is a kind of submicron order powder body material generally at 0.1～74 μ m, surface properties special (referring to table 2).

Iron-containing furnace dust grain diameter and shared pbw cartogram 2

Particle diameter	0～1μm	1～4μm		4～6μm		6～8μm		8～10μm		＞10μm
											Electric furnace dirt ash	50.2％	30.2％		6.2％		4.3％		1.5％		7.6％
Particle diameter	0.5μm	0.75μm		1μm		5μm		25μm		74μm
											Bof sludge	5.45％	4.9％		0.55％		27％		47.07％		14.4％
Particle diameter	0～47μm		47～74μm		74～93μm		93～115μm		＞115μm
											Blast furnace gas mud	22％		7％		18％		25％		28％

Above-mentioned three big technical characteristics are excavated the three big technical superioritys that the iron-containing furnace dust practical value need excite just.

2. comprehensive utilization scheme optimization

At first, more be similar to pozzuolanic characteristics,, adopt the alkaline excitation method to excavate the potential aquation gelling of iron-containing furnace dust with reference to the alkali slag cement principle at low-grade iron-containing furnace dust.

Secondly, at the characteristics of both sexes heavy metal element in the iron-containing furnace dust and alkali metal enrichment, utilize alkali lye dissolving and salting-out effect, extract these useful metals from iron-containing furnace dust, this improves one of importance of iron-containing furnace dust value just.

The 3rd, the characteristics superfine at iron-containing furnace dust iron oxide particle particle diameter, that particle surface character is special can become negative gel precipitation and recrystallization absorption base material.Boil on the basis in alkali lye heat, cooperate solvation (gelation) to handle, just can obtain having the iron-containing furnace dust suspension of gelling property.

To sum up state, can solve the iron-containing furnace dust whole synthesis cheaply by the alkali exciting method and utilize problem, realize utilization of resources maximization.The products scheme of comprehensive utilization is that alkali excites solvation iron-containing furnace dust suspension, and byproduct is crude zinc or zinc hydroxide etc.

Such scheme puts into practice, and accompanying drawing 1 is seen in its main production process and technical process.

3. stove dirt suspension production method

It is that means, solvation (gelation) are purpose that iron-containing furnace dust suspension production method excites with alkali.

The basic production operation: alkali lye heat is boiled → residue washing dealkalize → solvation processing three process (see figure 1).

Main production facility: heat is boiled insulation jar, liquid storing pool, drainer, filter, wet wheeling machine, slush pump, steam oven and concentration evaporator etc.

3.1. alkali lye heat is boiled

The object that alkali lye heat is boiled mainly is the low zinciferous various iron-containing furnace dusts of iron.Boil by alkali lye heat, quicken the alteration of iron-containing furnace dust mineralogical composition,, promote basic metal and amphoteric metal components dissolved to enter alkali lye to form a large amount of aquation mineral.

Ferriferous oxide in the iron-containing furnace dust (comprising iron sulphide, ferric metasilicate etc.) in alkali lye, is a kind of resistant mineral.And a spot of wustite (as sodium ferrite, calcium ferrite etc.) can generate the aquation mineral in the stove dirt in strong alkali solution; And hydrolysis will take place in neutrality～weakly alkaline solution:

MFe ₂O ₄+nH ₂O+aq＝MO·Fe ₂O ₃·nH ₂O+aq ...............(1)

(wustite) (wustite hydrate)

MFe ₂O ₄+H ₂O+aq＝Fe ₂O ₃+M(OH) ₂+aq ...............(2)

(wustite) (alkali or alkaline earth metal hydroxides)

Owing to add flux, calcium magnesium component is generally greater than sial component, particularly bof sludge in the iron-containing furnace dust, and basicity is generally more than 2.5.Calcium magnesium oxide and compound thereof exist, and help alkali lye effect performance, help the aquation mineral to form.

Ca(OH) ₂+Na ₂CO ₃+aq＝CaCO ₃+2NaOH+aq ...............(3)

CaSiO ₃+Na ₂CO ₃+aq＝CaCO ₃+Na ₂SiO ₃+aq ...............(4)

(Calucium Silicate powder) (water glass)

Following formula shows, exists a small amount of yellow soda ash harmless in the alkali lye, and alkaline earth salt has and helps that yellow soda ash is severe to be changed.

Excite down at alkali lye, silicate minerals generation alteration is along with part (SiO ₄) ^-4Run off, the silicon-oxy tetrahedron structural rearrangement generates new hydrated silicate mineral.As:

Na〔AlSi ₃O ₈〕+2NaOH+aq＝Na〔AlSi ₂O ₅〕(OH) ₂+Na ₂SiO ₃+aq .............(5)

(albite) (euthalite) (water glass)

3CaMgSiO ₄+4SiO ₂+10NaOH+aq＝Mg ₃〔Si ₂O ₅〕(OH) ₄+5Na ₂SiO ₃+3Ca(OH) ₂+aq ..(6)

(monticellite) (serpentine) (water glass)

The amphoteric metal oxide compound will be dissolved in the alkali lye, form the metal oxygen-containing acid sodium-salt.As:

ZnO+2NaOH+H ₂O+aq＝Na ₂ZnO ₂+aq ..................(7)

(sodium zincate)

The content of blast furnace dust (mud) carbon is very high, and carbon wherein mostly is the carbon black that unburnt carbon granules and condensation form and forms.They are Fails To Respond in alkali lye.But because due to particle characteristics and the sulfide, they very easily form colloidal solution with alkali lye, will influence liquid-solid separation.

3.1.1. ingredient requirement

Be used for the raw material that alkali lye heat boils and select TFe＜50%, the low zinciferous iron-containing furnace dust of iron of ZnO＞3% for use.Since its complex chemical composition, the bad uniform requirement of making.Its basicity of general requirement 〉=2 (are CaO/SiO ₂Ratio), be advisable with about 2.5.Need replenish CaO as deficiency.In addition, coarse particles component such as mechanical tramp material and specularite or flap need sift out in the iron-containing furnace dust.

3.1.2. batching

The alkali lye preparation: NaOH concentration is got 160～240g/L.Alkali lye is mainly from alkali lye reclaiming, that recycle (being commonly called as mother liquor) (seeing the 6th chapter for details) in the production.

Alkali lye and iron-containing furnace dust liquid-solid ratio are got 3～6 (weight ratios), can be with reference to ZnO content value in the iron-containing furnace dust.

3.1.3. alkali lye heat is boiled

Alkali lye heat is boiled the form of not having the heating of pressing that is, and gets final product in having the common insulation jar of agitator.Add the method that thermal recovery steam direct heating and indirect heating combine.Heat is boiled 90～102 ℃ of temperature, and heat is boiled 3～5 hours time under agitation condition.

3.1.4. liquid-solid separation

To utilize the characteristics of ferriferous oxide after alkali lye heat is boiled, leave standstill 2～4 hours than great (between 4～4.2).Supernatant liquor is isolated in clarification, as the alkali lye ore pulp (seeing the 5th chapter for details) of amphoteric metal oxide compounds such as extraction zinc.

Then, precipitation slag is carried out press filtration.The filtrate that obtains is returned in supernatant liquor; The filter residue that obtains will be used for the production of solvation iron-containing furnace dust suspension.

3.2. residue washing dealkalize

Residue washing adopts repeatedly backflush flow process.Generally through 3～4 washings, with the Na in the attached liquid ₂O content is reduced to below the 15g/L.This measure is not only in order to reclaim alkali lye, more in order to alleviate the disadvantageous effect of alkali to ironmaking.But, along with the slurries alkali concn reduces, viscosity also descends thereupon fast, will influence stove dirt suspension gelling property.Actual production can only be a trim point of seeking both.

Slurries after the washing through natural sedimentation, can obtain moisture at 40～50% precipitation body refuses.

3.3. precipitation body refuse solvation is handled

The precipitation body refuse is handled through solvation, just becomes stove dirt suspension product.The solvation measure has:

A. in body refuse, add 3～8% water glass (referring to account for the per-cent of body refuse cured article).Water glass technical requirements: modulus (m) 2.8～3.2, degree Beaume (Be ') 36～48 (density 1.4～1.5g/cm ³).

B. in body refuse, add few stable agent and thickening material.As add inorganic and organic materialss (all referring to account for the per-cent of body refuse cured article) such as 1～3% wilkinite, about 5% gas mud, 0.2～0.3% thicken pulp waste liquid.

C. carry out the mechanize wet-milling after precipitating body refuse and admixture mixing and stirring, require powder granule in the slurries≤20 μ m granularity components to account for more than 85%.

D. after the wet-milling, can consider in the stove dirt suspension a little aerating oxygen or add other oxygenant, promote that ferrous iron generates hydronium(ion) oxidation iron in the slurries.

4. the performance of stove dirt suspension and application

Alkali excites solvation iron-containing furnace dust suspension outward appearance to be the thickness pulpous state solution of chocolate, pH value 12～13, and water content is 40～50%, nontoxic odorless.Serum density is 1.5～1.6g/cm ³, viscosity 15～30 seconds (regular mud viscometer determining).It is the suspension that hydrated calcium silicate gel and stove dirt particulate are formed, and the thickness muddy has certain stability and gelling, and the slurry viscosity of heating descends, the mobile enhancing.The slurries solid substance mainly contains ferriferous oxide and powder granules such as silicate, oxyhydroxide.Residual Na ₂O＜5% is very little to the ironmaking disadvantageous effect.Slurries were placed 2～3 days at normal temperatures, and slightly the precipitating phenomenon takes place, and this does not influence use, satisfied the requirement of operation and use fully as its stability of jelling agent of a kind of liquid pulpous state.But along with time lengthening, slurries gelation (wearing out) trend is day by day obvious, and the slurry fluidity variation is so should use as early as possible after the output.

The smart powder agglomeration of iron is granulated and more or less need be used jelling agent, even if agglomerate adds jelling agent when batch mixing, will help to strengthen and granulate and the production efficiency raising.Stove dirt suspension has certain gelling property and stability, the jelling agent that can be used for agglomerate and oxide pellet early stage (normal temperature～hot stage), this purposes is not high to the requirement of jelling agent viscosity and gel intensity, can be easily carries out on existing sintered mix and pelletizing are made the water spray link of ball.The use if stove dirt suspension further matches with 15 metallurgical scientific-technical progress project-TYPE MINI-PELLET SINTERING TECHNIQUE will help this technology popularization to use.

But, stove dirt suspension is a kind of slurry material, is only applicable to do smart powder agglomeration and granulates, and the scope of application is limited to some extent.If wet smart powder need dry or dry.Production practice show, sinter mixture optimum moisture about 7%, pelletizing green-ball optimum moisture about 8.5%.The stove dirt suspension that adds respective amount under mixture moisture＜4% situation just can be obtained agglomeration granulating efficiency preferably.

5. the extracting method of byproduct-zinc

Except iron, some low-melting heavy metals and alkali metal are able to enrichment in the iron-containing furnace dust, and the zinc major part that wherein enriching quantity is bigger exists with oxide form.And zinc oxide is a kind of amphoteric metal oxide compound, and it not only can be dissolved in acid but also alkaline soluble, the molten solubleness of alkali that sour molten solubleness is higher than far away.But, the characteristics of iron-containing furnace dust still are the iron content height, if adopt acidleach to go out, have a large amount of iron and enter leach liquor increase deironing burden.If it is adopt alkali to leach, less to the influence of iron.So, with basis that the production of stove dirt suspension combines on, the extraction of zinc adopts the alkali lye dissolving-out method comparatively suitable in the iron-containing furnace dust.

Alkali lye heat is boiled (3.1. that sees before joint) behind the iron-containing furnace dust, dissolving in and become sodium zincate alkali lye ore pulp along with zinc oxide etc.Under suitable liquid-solid ratio, the zinc oxide leaching yield can reach more than 90%.Its chemical reaction mainly is:

ZnO+2NaOH+H ₂O＝Na ₂〔Zn(OH) ₄〕+87kJ/mol ................(8)

Following formula is thermo-negative reaction, and heating can promote this reaction forward to carry out.

As the formula (8), zinc element mainly is present in the alkali lye with zincic acid root complexing sodium-salt form in strong base solution, the dissolution equilibrium constant (K of formula (8) reaction _Sp) be:

$K_{\mathrm{sp}}=\frac{\left[{{\mathrm{Zn}\left(\mathrm{OH}\right)}_4}^{2-}\right]}{{\left[{\mathrm{OH}}^{-}\right]}^2}=2.19\×{10}^{-2}..............\left(9\right)$

Sodium zincate alkali lye ore pulp is commonly called as the thick liquid of ore pulp through the supernatant liquor (comprising filtrate) that liquid-solid separation obtains.Its technical qualification scope roughly exists: about 98 ℃ of slurry temperatures, and NaOH concentration 150～210g/L, ZnO concentration 15～35g/L, foreign matter content about 3% (mainly is SiO ₂, Al ₂O ₃With other easy molten sodium salts).The thick liquid of ore pulp just can adopt electrolytic process, salting-out process or semi-transparent embrane method to extract zinc powder or zinc hydroxide after treatment.The first two plants the method and technology maturation, has practical value.

5.1. electrolytic process is extracted crude zinc

Electrolytic process is a direct electrowinning zinc powder from alkali lye, and technology is also uncomplicated.But it is very tight that this method requires electrolyte quality, the foreign matter content general requirement is lower than≤and 0.5%.So the thick liquid of ore pulp must pass through purifying treatment, can serve as electrolytic solution and use.

The thick liquid of ore pulp purifies mainly in order to remove SiO ₂, Al ₂O ₃, removal methods has the admixture of interpolation or iron anode electrolysis to remove impurity.In addition, on the aluminium base plinth of desiliconization, add a certain amount of zinc powder, the higher metal replacements of electronegative such as lead, cadmium are precipitated out.

Purify ore pulp seminal fluid electrolysis after impurity elimination is handled and be and utilize negative electrode ejected electron in the electrochemical reaction, the oxidisability zine ion is reduced, generate the active zinc powder deposition.Its processing condition are: bath voltage 3～3.5v, current density 800～1600A/m ², cathode efficiency 90～95%, 40～50 ℃ of electrolysis temperatures, electrolysis time 40～50 minutes.

Electrolysis is resulting to be rough zinc powder, also needs melting to purify, and just can obtain purity at pure zinc products more than 99.8%.

5.2. salting-out process extracts zinc hydroxide

The ultimate principle of salting-out process extraction zinc hydroxide is the characteristic according to liquid caustic soda, in NaOH spent liquor evaporation concentration process, with the raising of NaOH concentration, Na ₂(Zn (OH) ₄) (also comprise other sodium salts such as Na ₂SO ₄, Na ₂CO ₃Deng) solubleness in alkali lye reduces gradually, be sodium zincate crystal of hydrate body (salt slag) and separate out gradually.When NaOH concentration during in 0.4 (500g/L, alkali lye density 1.25), the remaining quantity of sodium zincate in alkali lye is less than thousandth.The salting-out effect of Here it is alkali lye.

Utilize that the salting-out effect of alkali lye inspissation just can be isolated sodium zincate from alkali lye, hydrolysis obtains zinc hydroxide then.Therefore, salting-out process will be referred from liquid caustic soda evaporation concentration production method and process unit, and its technical process generally need be through purifying, evaporate, saltout and hydrolysis four procedures being finished (referring to accompanying drawing 2).

5.2.1 the thick liquor cleaning procedure of ore pulp

In the thick liquid of ore pulp, add powdery CaO, with SiO ₂, Al ₂O ₃Reaction generates precipitations such as calcium-silicon slag or calcium aluminate.The CaO addition is according to (CaO/SiO ₂)=1.5: 1 ratio is about every liter of solution and adds 20～50 gram CaO.Stir 1.5～2 hours after-filtration and remove throw outs such as calcium-silicon slag, calcium aluminate (throw outs such as sedimentary calcium-silicon slag, calcium aluminate will be sent to the production of stove dirt suspension and serve as the body refuse raw material).But, the alkali lye of NaOH concentration about 200g/L is difficult to reach ideal effect with CaO desiliconization aluminium.So, also can directly adopt the thick liquid of ore pulp at salting-out process, do not do purification, be put into last Zn (OH) ₂Remove these impurity during purification.

5.2.2 ore pulp spent liquor evaporation operation

Clarifying ore pulp alkali lye reheats 100 ℃, promptly sends into evaporator evaporation and concentrates, and the inspissation concentration of lye requires to reach 400～500g/L.Generally need all to adopt the negative pressure operation through dual evaporation, negative pressure is about 80KPa.The reliable pressure reduction of ore pulp alkali lye sucks.(0.35～0.4MPa) is thermal source with bright steam in heating.

In evaporative process,, just there are sodium zincate and other sodium salts to separate out along with ore pulp alkali lye moisture evaporation, concentration increase.In fact, evaporization process is the stage that the sodium salt mass crystallization is separated out.Realize that by clarification and throw out vacuum filtration liquid-solid separation obtains inspissation alkali lye (comprising supernatant liquor and first-time filtrate) and a salt slag.

Inspissation alkali lye is with further cooling and desalting.A salt slag will be sent to hydrolyzing process and isolate zinc hydroxide etc.

5.2.3 cooling salting-out procedures

Salting-out procedures to as if inspissation alkali lye, purpose is further desalination, purifying alkali lye, its means mainly are cooling and desaltings.Inspissation alkali lye is delivered to the bucket of saltouing, under agitation cool off indirectly with cold water and analyse salt, solution temperature requires to drop to below 35 ℃.In inspissation alkali lye temperature-fall period, remaining sodium zincate and other sodium salts are further separated out.And then, realize that by clarification and throw out vacuum filtration liquid-solid separation obtains purifying high alkali liquid (comprising supernatant liquor and secondary filtrate) and secondary salt slag.

The purifying high alkali liquid will return the new alkali lye of preparation, recycle.

Secondary salt slag mixes with a salt slag, changes the washing hydrolyzing process over to.

5.2.4 washing hydrolyzing process

Salt slag and secondary salt slag total amount account for about 10% of inspissation alkali lye.The salt slag is made up of easy molten sodium salt and slightly soluble oxygen acid sodium salt.The salt slag is in adding the water washing process, and at first the easy molten sodium salt of flush away is (as Na ₂SO ₄, Na ₂CO ₃With NaCl etc.), and heavy metal oxygen acid sodium salt successively hydrolysis generate corresponding oxyhydroxide or the metal salt precipitate thing is separated.With the sodium zincate is example, and its hydrolysis reaction is as follows:

Na ₂〔Zn(OH) ₄〕+aq＝Zn(OH) ₂↓+2NaOH+aq ............(10)

The size of various heavy metal compound meltages and solution pH value are closely related.As cadmium hydroxide, solution PH=11.5 o'clock solubleness minimum; Zinc hydroxide solution PH=9 o'clock solubleness minimum.Therefore, can rely on the method for adjustment, control washings pH value the heavy metal hydroxide rough segmentation to be come out at the washing hydrolysis stage.

The salt slag separates the zinc hydroxide that obtains by the washing hydrolysis, can further take sour dissolution method or method for smelting reduction of Ni to extract pure zinc.

6. alkali lye reclaims, recycles

In order to reduce cost and to alleviate the disadvantageous effect of alkali to ironmaking, alkali lye must reclaim in the production process, through handling the alkali lye that (mainly being inspissation) is mixed with suitable concentration again, recycles.

Owing to extract the method difference of zinc, the alkali lye that electrolytic process and salting-out process reclaim is different.Two kinds of alkali lye that electrolytic process reclaims are middle high alkali liquid (washings (the NaOH concentration 20～80g/L) of NaOH concentration 120～200g/L) and diluted alkaline concentration.Two kinds of alkali lye that salting-out process reclaims are purifying high alkali liquid (washings (the NaOH concentration 20～80g/L) of NaOH concentration 400～500g/L) and diluted alkaline concentration.Washings (sig water) difference that both reclaim is little.

The alkali lye treatment measures that reclaim have:

1. washings (sig water) is at first carried out desiliconization of lime wet method and severe changing.General 10～20g/L powdery CaO that adds stirred 1～2 hour, left standstill 2～3 hours.Main chemical reactions is in the solution:

CaO+Na ₂SiO ₃+(n+1)H ₂O+aq＝CaSiO ₃·nH ₂O+2NaOH+aq ....(11)

CaO+Na ₂CO ₃+H ₂O+aq＝CaCO ₃ ^-+2NaOH+aq ...........(12)

Generate hydratable calcium white residue etc. in the reaction and collect, change over to the production of stove dirt suspension through precipitation.

2. then washings (sig water) is carried out dehydration by evaporation, NaOH concentration is concentrated to about 200g/L and gets final product.Whole washingss that electrolytic process reclaims all must be through handling like this, and the washings that salting-out process reclaims partly needs such processing (its amount is decided by the material balance needs).

Prepare the alkali lye of required concentration after the above-mentioned washings inspissation with other alkali lye that reclaim together, just can recycle.Alkali lye compound concentration scope: NaOH content 160～240g/L.Mainly from the circulation alkali liquor (being commonly called as mother liquor) of reclaiming, the consumption of alkali is limited for alkali lye in the production.By experience ton stove dirt solid caustic soda consumption be ± 20kg.The NaOH amount of adding is each time just replenished alkali lye circulation Na ₂The loss amount of O.

The present invention is further illustrated below in conjunction with embodiment

Embodiment 1:

Preparation stove dirt suspension is used for the smart powder sintering material of iron and strengthens granulation.

(1) the alkali lye heat method of boiling prepares stove dirt suspension and extracts byproduct zinc:

Alkali lye preparation: Na ₂O 180g/L.

The iron-containing furnace dust raw material: based on electric furnace dirt ash, TFe=37%, ZnO=9%, low iron contains zinc.Admixture has 32% iron-containing furnace dusts such as sinter machine dedusting ash, bof sludge and gas ash in addition.

Alkali lye heat is boiled: liquid-solid ratio gets 3.7, and heat is boiled on request, 3 hours 40 minutes time.

Liquid-solid branch filter: realize liquid-solid separation by clarification and throw out pressure filtration.

Liquid-solid separation obtains alkali lye ore pulp (comprising supernatant liquor and first-time filtrate), passes in the production of byproduct zinc.Adopt salting-out process from the alkali lye ore pulp, to isolate zinc hydroxide.

The filter residue that liquid-solid branch filter obtains will be used for the production of solvation iron-containing furnace dust suspension.

The filter residue solvation is handled: add 5% water glass, 1% wilkinite and 6% gas mud in the precipitation body refuse after the residue washing dealkalize, mix wet-milling afterwards, feed a little oxygen and agitation as appropriate.Obtain moisture at 47% stove dirt suspension finished product.

(2) stove dirt suspension is used for the jelling agent that the smart powder sintering material of iron is strengthened granulation:

The jelling agent that stove dirt suspension strengthen to be granulated as sintered material, be adopt slush pump pressurization sprinkling form in the sintered material mixed processes with itself and compound thorough mixing such as the smart powder of iron, substitute the at present general mixing machine mode of spraying water.

At first the smart powder of thin iron (admixture has 22% high-grade iron-containing furnace dust) is sprayed stove dirt suspension, stirring and evenly mixing is stand-by.First batch of mixing fine powders material moisture is grasped at 10 ± %.

Then that proportioning is the good smart powder sintering material of moisture＜4% iron (comprising first batch of mixing fine powders material) is sent into drum pelletizer, is sprayed stove dirt suspension through stirring, and (moisture controlled 5～10 minutes time, is served the sinter machine sintering again 7 ± %) to strengthen granulation.

Employing has the stove dirt suspension of certain gelling property and strengthens granulation, and effect is obvious.Reached more than 80% greater than the 5mm grade in the compound, the sintering pallet layer thickness increases 150mm, and bed permeability is greatly improved.Productivity of sintering machine is by 1.5t/m ²H brings up to 1.8t/m ²H, solid burnup drops to 57kg/t by 65kg/t, and FeO reduces to below 6%.

Embodiment 2:

Preparation stove dirt suspension is used for the smart powder acid pellet of iron compound roll extrusion balling-up.

(1) the alkali lye heat method of boiling prepares stove dirt suspension and extracts byproduct zinc:

Alkali lye preparation: Na ₂O 200g/L.

The iron-containing furnace dust raw material: based on electric furnace dirt ash, TFe=33%, ZnO=11%, the rich zinc of low iron.Admixture has 36% iron-containing furnace dusts such as sinter machine dedusting ash, bof sludge and gas ash in addition.

Alkali lye heat is boiled: liquid-solid ratio gets 4.1, and heat is boiled on request, 4 hours time.

Liquid-solid branch filter: realize liquid-solid separation by clarification and throw out pressure filtration.

Liquid-solid separation obtains alkali lye ore pulp (comprising supernatant liquor and first-time filtrate), passes in the production of byproduct zinc.Adopt salting-out process from the alkali lye ore pulp, to extract zinc hydroxide.

The filter residue that liquid-solid branch filter obtains will be used for the production of solvation iron-containing furnace dust suspension.

The filter residue solvation is handled: add 6% water glass, 1% wilkinite and 0.2% thickened pulp waste liquid in the precipitation body refuse after the residue washing dealkalize, mix wet-milling afterwards, obtain moisture at 50% stove dirt suspension finished product.

(2) stove dirt suspension is used for the jelling agent of the smart powder acid pellet of iron compound roll extrusion balling-up

Employing has the jelling agent of the stove dirt suspension of certain gelling property as the acid pellet compound, substitutes general interpolation wilkinite mode at present.Raw material is the smart powder (moisture 9.7%) of iron that wets, and allocates 5% rhombspar stone flour (granularity-200 order accounts for 80%) into, with production solvation acid pellet.Compound is dried to moisture≤2% by the garden cylinder drier.

Spray stove dirt suspension jelling agent toward the smart powder compound of the iron of oven dry, thorough mixing is mixed thoroughly, and mixture moisture is controlled at 8.5%, sends into balling disc roll extrusion balling-up.Sieve out the qualified pelletizing of diameter 15mm size and send into chain wall machine-revolution kiln drying and oxidation and sinter.

Claims (4)

1. metallurgical industry waste material-iron-containing furnace dust alkali excites comprehensive utilization method, it is characterized in that boiling iron-containing furnace dust and solvation processing by alkali lye heat, inspire the potential aquation gelling of iron-containing furnace dust, promote the useful metal element to dissolve in alkali lye simultaneously and be equipped with salting-out process it is separated; The comprehensive utilization product is that alkali excites solvation iron-containing furnace dust suspension, and mainly as the jelling agent of the smart powder agglomeration granulation of iron, byproduct can obtain crude zinc or zinc hydroxide etc.

2. according to claim 1, alkali excites the production method of solvation iron-containing furnace dust suspension: and iron-containing furnace dust alkali lye heat boils → and precipitation body refuse solvation after the residue washing dealkalize → washing of liquid-solid resulting separation handles.

3. according to claim 1, byproduct crude zinc or zinc hydroxide etc. be from iron-containing furnace dust alkali lye heat boil the back liquid-solid resulting separation ore pulp alkali lye extract, extracting method is except existing electrolytic process, according to the liquid caustic soda characteristic and transplant its concentration method, utilize the salting-out effect of inspissation alkali lye to isolate sodium zincate and then the washing hydrolysis generates zinc hydroxide.

4. according to claim 1,2,3, technical qualification and technology characteristics that iron-containing furnace dust alkali lye heat is boiled: low iron contains the iron-containing furnace dust of zinc (TFe＜50%, ZnO＞3%), alkali lye compound concentration 160～240g _(NaOH)/ L, liquid-solid ratio 3～6 (weight ratio), heat are boiled 90～102 ℃ of temperature, and under agitation condition, heat was boiled 3～5 hours.

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