CN104556182B - Method for preparing solid high-efficiency flocculant polyaluminum chloride from fly ash - Google Patents

Abstract

The invention discloses a method for preparing a solid high-efficiency flocculant polyaluminum chloride from fly ash. According to the method, by using the fly ash as the raw material, an intermediate product alpha-Al(OH)3 is adopted to prepare the solid high-efficiency flocculant polyaluminum chloride 13 [Al13(OH)24(H2O)24Cl15.13H2O] (P-Al13 for short) crystal. The method comprises the following steps: reacting an aluminiferous solution, which is prepared by carrying out acid dipping on clinker prepared by carrying out high-temperature solid-phase reaction on sodium carbonate and fly ash, with sodium hydroxide to obtain the alpha-Al(OH)3 intermediate product, carrying out hydrolysis-polymerization reaction with hydrochloric acid under the conditions of high temperature and normal pressure until a certain degree of alkalization, naturally crystallizing to precipitate the P-Al13 solid product, and merging the residual mother solution with the acid dipping solution to implement reutilization, thereby achieving the goal of zero discharge of aluminum ions. The flocculation test indicates that the method has the advantages of low loss rate of aluminum ions and high conversion rate of P-Al13; the obtained solid product P-Al13 has obviously better flocculation effects than Keggin-Al13([AlO4Al12(OH)24(H2O)12]7+); and the solid high-efficiency flocculant polyaluminum chloride conforms to the specifications for premium grades in national standard (GB15892-2009).

Description

A kind of method that solid-state efficient flocculant aluminium polychlorid is developed for raw material with flyash

Technical field

The present invention relates to total utilization of PCA and solid-state High-purity Polyaluminum Chloride preparation method, refer in particular to one kind with fine coal The method that ash develops solid-state efficient flocculant aluminium polychlorid for raw material.

Background technology

Flyash is the complicated multiphase solid waste that left behind after coal burns in burning boiler.Flyash main Thing phase composition is mullite, and primary chemical composition is SiO₂, Al₂O₃.At present, many experts and scholars both at home and abroad are engaged in flyash Comprehensive development and utilization is it is achieved that flyash is widely used in construction material, agricultural (plantation) cultivation, concrete construction, chemicalization The fields such as work；Also good economic benefit, environmental benefit and social benefit is created while turning waste into wealth.With flyash it is The process that efficient flocculant realizes sewage, waste water prepared by raw material, is one of method of flyash high value added utilization.At present, real Existing having prepares silicic acid aluminium flocculating agent, silicate aluminium ferric flocculating agent, aluminium iron polychloride floculant with flyash for raw material.And utilize Coal ash for manufacturing is standby to be considered most effective flocculation morphology in polymeric aluminum, has the Al of superior water purification performance₁₃But have no report.

Al₁₃Because of its nano molecular size and high electric charge it is considered to be minimum and most stable of receive in polymeric aluminum chlorides solution Rice species.However, each technical field attempts various synthesis preparation methods both at home and abroad so far, all cannot obtain with commercial Application valency The high concentration of value, high Al₁₃The polymerization aluminum solutions of content and rafifinal 13 solid product.

Sun Zhong is in Chinese J.Struct.Chem.25 (10) within 2006：1217-1227 reports and Keggin-Al₁₃ There is same polymeric degree, composition, the different P-Al of structure₁₃(Al₁₃(OH)₂₄(H₂O)₂₄Cl₁₅·13H₂O), its polycation carries 15 positive charges, number of patent application 200510064782.6 discloses under 200 DEG C of autoclave conditions, with aluminium hydroxide, crystallization Aluminum chloride, water are obtained high-purity P-Al for raw material₁₃Method, and prove P-Al₁₃Ratio has all been shown under different pH value Keggin-Al₁₃Turbid ability, broader effective flocculation is preferably gone to add the water pH value of scope and adaptation.It is indicated above that P- Al₁₃It is a kind of superior performance, rising efficient flocculant, to developing Huanghe water, process various waste water, frugally Lower water resource is significant.

Content of the invention

The technical problem to be solved in the present invention is to provide one kind to develop the polymerization of solid-state efficient flocculant with flyash for raw material The method of aluminum chloride, this method with flyash as raw material, by intermediate product α-Al (OH)₃Development high-purity, form are single The superior solid-state efficient flocculant P-Al of flocculating property₁₃.

For solving above-mentioned technical problem, the present invention proposes following scheme：A kind of efficient for raw material development solid-state with flyash The method of flocculant poly aluminum chloride it is characterised in that with flyash as raw material, by intermediate product α-Al (OH)₃Develop Al₁₃ (OH)₂₄(H₂O)₂₄Cl₁₅·13H₂(letter is calculated as P-Al to O₁₃), including following five steps：

1. high-temperature fusion reaction：Flyash and sodium carbonate are pressed 0.8～2.0: the 1 finely ground mixing of mass ratio, in Muffle furnace In calcination 30～150min at 750～950 DEG C, be fully ground standby after clinker cooling to room temperature；

2. acid-leaching reaction：In above-mentioned grog, add the hydrochloric acid of 3～12mol/L, every gram of grog correspondence Jia 4～20mL body Long-pending hydrochloric acid, after being sufficiently stirred for, room temperature is filtrated to get pickle liquor after standing 5～30min；

③α-Al(OH)₃Preparation：Take above-mentioned pickle liquor, Deca concentration is more than 4mol/L's under the conditions of 70 DEG C～90 DEG C Sodium hydroxide solution, to pH=7.5～8.5, is precipitated, and filters to obtain filter cake as α-Al (OH)₃, after repeatedly washing and drying Finely ground standby；

④P-Al₁₃Preparation：By α-Al (OH)₃Under reflux conditions with 8～12mol/L hydrochloric acid reaction, reaction temperature exists 110～120 DEG C, condition of normal pressure issues unboiled water solution-polyreaction 6～10 hours, obtains storing solution so as to hydroxide aluminium ratio basicity is 0.4～1.3, after filtered while hot, filtrate moves into crystallizer, evaporative crystallization at room temperature～50 DEG C, Al to be separated out₁₃(OH)₂₄ (H₂O)₂₄Cl₁₅·13H₂Separate after O crystal or powder, solid product is scrubbed, at room temperature～50 DEG C, dry product, prepared solid-state Efficient flocculant Al₁₃(OH)₂₄(H₂O)₂₄Cl₁₅·13H₂O, filtrate reusable edible；

5. mother liquid recycling：The mother solution of the 4. step gained is fully incorporated the 2. circulation profit in the pickle liquor of step gained With achievable aluminium ion conversion ratio maximizes, the purpose of zero-emission.

The experimental principle of this method：

1st, solid phase fusion reaction：

The principal crystalline phase material of flyash is mullite, and amorphous phase material is alumina silicate glass body.Mullite is in room temperature Do not dissolve in down acid, be also insoluble in alkali.But under heating condition, can react with alkaline matter.This experiment is with sodium carbonate for helping Flux, under the high temperature conditions, flyash is reacted with sodium carbonate, generates nepheline.

Al₆Si₂O₁₃+Na₂CO₃=2NaAlSiO₄+2Al₂O₃+CO₂

Meanwhile, the Al that reaction generates₂O₃With the magma cell in flyash also can and Na₂CO₃React：

Al₂O₃+2SiO₂+Na₂CO₃=2NaAlSiO₄+CO₂

2nd, acid-leaching reaction：

Nepheline is acid soluble material, can be decomposed by acid and generate silica gel and Al³⁺；Realize efficiently separating of sial.

NaAlSiO₄+4H⁺=Al³⁺+Na⁺+H₂O+H₂SiO₃

3、α-Al(OH)₃Preparation：Sodium hydroxide solution and liquor alumini chloridi react the aluminium hydroxide that can obtain variform, But by controlling temperature and pH, α-Al (OH) can be obtained₃Single form.

4、P-Al₁₃Preparation：

By α-Al (OH)₃Hydrolyze-polyreaction reach certain basicity with hydrochloric acid at a temperature of determining, in solution Just obtain including P-Al₁₃In interior various polymerization al species, after reaching corresponding saturation, P-Al₁₃Hydrochlorate can be analysed naturally Go out crystallization.

5th, Recycling Mother Solution：

Due to preparing P-Al₁₃Reaction do not introduce any other ion, so remaining mother solution can be merged with pickle liquor Recycle, reach the purpose of zero-emission.

High-temperature fusion reaction described in this method refers to：Using the high-temperature solid-phase sintering method of sodium carbonate and flyash, anticipate By the main thing phase mullite in flyash, react with sodium carbonate at high temperature and generate the nepheline grog being soluble in acid；Acidleach Reaction refers to：By the salt acid dip of above-mentioned grog, so that silicon and aluminum is efficiently separated, obtain the chlorine being main foreign ion with iron ion Change aluminum solutions；α-Al(OH)₃Preparation refer to：By pickle liquor, under constant temperature, adjust pH so that α-Al is obtained with sodium hydroxide (OH)₃；P-Al₁₃Preparation refer to：With α-Al (OH)₃Hydrolyze with hydrochloric acid under the conditions of high-temperature pressure-be polymerized instead for raw material Storing solution should be obtained, stand under room temperature, P-Al₁₃Hydrochlorate is separated out crystallization naturally, obtains product after filtration；Mother liquid recycling Refer to：By P-Al₁₃Preparation process in the mother solution of gained be fully incorporated in the pickle liquor of acid-leaching reaction gained and recycle, can be real Existing aluminium ion conversion ratio maximizes, the purpose of zero-emission.

The mass ratio of the flyash described in this method and sodium carbonate, and the determination of calcining heat and time is to guarantee powder In coal ash, main thing phase mullite is reacted completely with sodium carbonate, and premised on not causing energy waste.

The sour consumption of the hydrochloric acid leaching grog described in this method is according to the leaching rate maximum of aluminum, loss rate in flyash It is minimised as foundation to draw；The excessive recyclable recycling of hydrochloric acid.

α-Al (OH) described in this method₃Preparation temperature be 70～90 DEG C, adjust pH value 7.5～8.5.

α-Al (OH) described in this method₃It is not necessarily intended to the freshly prepd compound of Seeking Truth.

Described in this method with α-Al (OH)₃For raw material in 110～120 DEG C of temperature ranges, with salt under condition of normal pressure Acid hydrolyzes-polyreaction 6～10 hours, obtains storing solution.

α-Al (OH) described in this method₃Ensure storing solution basicity (the hydroxyl aluminum of end reaction with the used in amounts of hydrochloric acid Than) it is 0.4～1.3.

Gained α-Al (OH) described in this method₃Al species can be implemented under condition of normal pressure with hydrochloric acid reaction and reach Preparation P-Al₁₃Basicity.

α-Al (OH) described in this method₃With the reactant liquor of hydrochloric acid, can naturally separate out P-Al at ambient temperature₁₃Knot Crystalline substance, directly obtains solid-state efficient flocculant after filtration, need not any other solidification equipment and technique.

Preparation P-Al described in this method₁₃Required raw material is only α-Al (OH)₃With hydrochloric acid it is not necessary to other any urge Agent or reagent, do not introduce the other any impurity ions in addition to Al (III) in preparation process.

P-Al described in this method₁₃Hydrochloric acid salts out the remaining mother solution reusable edible after crystallization, is a kind of aluminium ion Loss rate bottom, high conversion rate, the preparation P-Al of zero-emission₁₃Method.Advantages of the present invention：

The present invention has the advantages that to project as follows：

1st, flyash is converted into solid-state efficient flocculant by this method, there is provided it is comprehensive that one kind realizes flyash high added value Using approach.

2nd, this method is easily operated, affecting parameters are few, product quality is secure.

3rd, this method has sought one kind by adjusting temperature, pH value, quickly prepares α-Al (OH)₃Method.

4th, this method can be implemented in and prepares P-Al with aluminium hydroxide for raw material under condition of normal pressure₁₃.

5th, this method makes P-Al by adjusting degree of supersaturation₁₃Naturally separate out crystallization, obtain solid-state efficient flocculant, need not appoint What its solidification equipment and technique.

6th, this method preparation P-Al₁₃During do not introduce other any impurity ions in addition to Al (III).

7th, its effectively flocculation composition P-Al of this method products therefrom₁₃Content up to more than 93%, excellent aqueous solubility, there is no water Insoluble matter, products therefrom meets national standard (GB15892-2009) high-class product specification.

8th, this method is a kind of aluminium ion loss rate bottom, high conversion rate, the preparation P-Al of zero-emission₁₃Method.

9th, products obtained therefrom P-Al of the present invention₁₃Flocculating effect is better than Keggin-Al₁₃([AlO₄Al₁₂(OH)₂₄(H₂O)₁₂]⁷⁺). Contrast experiment is as shown in table 1.From table, the P-Al of present invention preparation₁₃With Keggin-Al₁₃Compare, no matter high concentrtion is stable Water sample and the unstable water sample of low turbidity, all show and compare Keggin-Al₁₃Superior flocculating effect.

Table 1, P-Al₁₃With Keggin-Al₁₃ ^aFlocculating experiment^bResult

Annotation^a：Keggin-Al₁₃Preparation is using a slowly alkaline process：Under the conditions of 80 DEG C of constant temperature oil bath, strong magnetic agitation, to AlCl₃It is slowly added dropwise NaOH solution, rate of addition controls in 0.6mL/min in solution.It is cooled to room temperature after completion of dropping, Ripening certain time must contain Keggin-Al₁₃Polymerization PAC solution, Al_bContent 80% about,²⁷Al-NMR characterizes proves that it is main For Keggin-Al₁₃.Annotation^b：Flocculating experiment adopts chamber test method：Instrument adopts JJ-4 type six motor stirrer, will In 500mL simulated water sample injection beaker, start stirring, under quick stirring (rotating speed is 200r/min) to water sample in put into certain The flocculant of amount, is changed to (rotating speed is 40r/min) stirring 15min at a slow speed, stops stirring and standing after continuing quick stirring 1min Sedimentation 15min.Precipitation terminates to draw clarification aqueous humor at 1cm under liquid level, detects that it is remaining using 2100N type transmissometer Turbidity.)

Brief description

Fig. 1 is process chart.

Fig. 2 is intermediate product α-Al (OH)₃XRD spectrum.

Fig. 3 is to separate out P-Al for the first time₁₃The XRD spectrum of product.

Fig. 4 is to separate out P-Al second₁₃The XRD spectrum of product.

Fig. 5 is that third time separates out P-Al₁₃The XRD spectrum of product.

Fig. 6 is the 4th precipitation P-Al₁₃The XRD spectrum of product.

Specific embodiment

The present invention will be further described by the following examples, but the scope of protection of present invention not limitation in The scope of embodiment protection.

1st, high-temperature fusion reaction：The flyash of Huhehaote power plant and sodium carbonate are pressed 1.2: 1 mass ratio, both generals exist Finely ground mixing in mortar, 870 DEG C of calcination 80min in Muffle furnace.Clinker cooling is fully ground standby to room temperature.(powder Coal ash Al₂O₃Content is 49.2%)

2nd, acid-leaching reaction：Take above-mentioned grog 75.2g in beaker, add 380mL concentrated hydrochloric acid and 20mL distilled water, through fully After stirring, room temperature stands 5min, is filtrated to get pickle liquor.

3、α-Al(OH)₃Preparation：Take above-mentioned pickle liquor, Deca concentration is the sodium hydroxide of 8mol/L under the conditions of 70 DEG C Solution, to pH=8, is precipitated, and filters to obtain filter cake as α-Al (OH)₃, finely ground standby after repeatedly washing and drying.Product XRD characterization result is shown in accompanying drawing 2.

4、P-Al₁₃Preparation：(1) take 43g α-Al (OH)₃In 500mL there-necked flask, add the dense salt of 74mL under reflux conditions Acid and 15mL distilled water, after reaction 30min under room temperature condition, are warming up to 120 DEG C and continue to react, stopped reaction after coreaction 6h, Filtered while hot obtains storing solution, and its basicity (hydroxide aluminium ratio) is 1.2, moves into crystallizer and in room temperature condition spontaneous nucleation, treats Separate out Al₁₃(OH)₂₄(H₂O)₂₄Cl₁₅·13H₂O(P-Al₁₃) separate after crystal.Product washing with alcohol, claims after room temperature air-dries Amount preserves.

Sample analysis result：Solid product gross mass：13.51g, wherein P-Al₁₃Mass content is 94.2%, and aluminium ion turns Rate：16.28%.Remaining mother solution 140.48g.The XRD characterization result of product is shown in accompanying drawing 3.

(2) the remaining mother solution of (1) is incorporated to the pickle liquor of second step, under the conditions of 70 DEG C Deca sodium hydroxide to pH=8, Obtain α-Al (OH) again₃Solid, takes the α-Al (OH) of 43g₃Repeat (1st) step experimental procedure, obtain P-Al again₁₃Crystallization.

Sample analysis result：Solid product gross mass：13.49g, wherein P-Al₁₃Mass content is 93.5%, with for the first time Reacting worthwhile total aluminium ion conversion ratio is：28.58%.The XRD characterization result of remaining mother solution 140.50g product is shown in accompanying drawing 4.

(3) the remaining mother solution of (2) is incorporated to the pickle liquor of second step, under the conditions of 70 DEG C Deca sodium hydroxide to pH=8, Obtain α-Al (OH) again₃Solid, takes the α-Al (OH) of 43g₃Repeat (1st) step experimental procedure again, obtain P-Al again₁₃Knot Brilliant.

Sample analysis result：Solid product gross mass：13.52g, wherein P-Al₁₃Mass content be 95.7%, with front twice Reacting worthwhile total aluminium ion conversion ratio is：34.44%.Remaining mother solution 140.48g.The XRD characterization result of product is shown in accompanying drawing 5.

(4) the remaining mother solution of (3) is incorporated to the pickle liquor of second step, under the conditions of 70 DEG C Deca sodium hydroxide to pH=8, Obtain α-Al (OH) again₃Solid, takes the α-Al (OH) of 43g₃Repeat (1st) step experimental procedure again, obtain P-Al again₁₃Knot Brilliant.

Sample analysis result：Solid product gross mass：13.53g, wherein P-Al₁₃Mass content is 94.1%, with first three time Reacting worthwhile total aluminium ion conversion ratio is：40.12%.Remaining mother solution 140.47g.

Can Theoretical Calculation be gone out according to the aluminium ion conversion ratio of first four times experiments：After 5th mother liquid recycling, aluminium ion turns Rate up to：48.07%；The aluminium ion conversion ratio of the 6th mother liquid recycling is：50.96%.I.e. Recycling Mother Solution number of times is got over Many, aluminium ion conversion ratio is higher, finally can achieve aluminum ions zero-emission.

Claims (1)

1. a kind of the method for solid-state efficient flocculant aluminium polychlorid is developed it is characterised in that with fine coal for raw material with flyash Ash is raw material, by intermediate product α-Al (OH)₃Develop Al₁₃(OH)₂₄(H₂O)₂₄Cl₁₅·13H₂O, letter is calculated as P-Al₁₃, including Five steps below：

1. high-temperature fusion reaction：Flyash and sodium carbonate are pressed 0.8～2.0: the 1 finely ground mixing of mass ratio, 750 in Muffle furnace Calcination 30～150min at～950 DEG C, is fully ground standby after clinker cooling to room temperature；

2. acid-leaching reaction：In above-mentioned grog, adding the hydrochloric acid of 3～12mol/L, every gram of grog correspondence Jia 4～20mL volume Hydrochloric acid, after being sufficiently stirred for, room temperature is filtrated to get pickle liquor after standing 5～30min；

③α-Al(OH)₃Preparation：Take above-mentioned pickle liquor, Deca concentration is more than the hydrogen-oxygen of 4mol/L under the conditions of 70 DEG C～90 DEG C Change sodium solution to pH=7.5～8.5, be precipitated, filter to obtain filter cake as α-Al (OH)₃, finely ground after repeatedly washing and drying Standby；

④P-Al₁₃Preparation：By α-Al (OH)₃Under reflux conditions with 8～12mol/L hydrochloric acid reaction, reaction temperature 110～ 120 DEG C, condition of normal pressure issues unboiled water solution-polyreaction 6～10 hours, obtains storing solution so as to basicity, and that is, hydroxide aluminium ratio is 0.4～1.3, after filtered while hot, filtrate moves into crystallizer, evaporative crystallization at room temperature～50 DEG C, Al to be separated out₁₃(OH)₂₄ (H₂O)₂₄Cl₁₅·13H₂Separate after O crystal or powder, solid product is scrubbed, at room temperature～50 DEG C, dry product, prepared solid-state Efficient flocculant Al₁₃(OH)₂₄(H₂O)₂₄Cl₁₅·13H₂O, filtrate reusable edible；

5. mother liquid recycling：The mother solution of the 4. step gained is fully incorporated the 2. recycle in the pickle liquor of step gained.