阅读说明：本技术 一种利用富铝黏土制备硫酸铝净水剂并联产微细硅酸的方法 (Method for preparing aluminum sulfate water purifying agent and co-producing micro silicic acid by utilizing aluminum-rich clay ) 是由 潘爱芳 马昱昭 孙悦 马润勇 于 2021-10-20 设计创作，主要内容包括：本发明涉及一种利用富铝黏土制备硫酸铝净水剂并联产微细硅酸的方法,该方法通过添加助剂,进行活化焙烧和水酸联合分步溶出,可将富铝黏土中的铝分离提取,并转化为硫酸铝净水剂产品,同时将硅分离提取并制备为微细硅酸。本发明方法具有工艺过程简单、对设备无特殊要求、能耗低、工艺参数可控性好、成本低等优点,为富铝黏土的开发利用开辟了新的途径。(The invention relates to a method for preparing an aluminum sulfate water purifying agent and coproducing fine silicic acid by utilizing aluminum-rich clay. The method has the advantages of simple process, no special requirement on equipment, low energy consumption, good controllability of process parameters, low cost and the like, and opens up a new way for the development and utilization of the aluminum-rich clay.)

1. A method for preparing an aluminum sulfate water purifying agent and coproducing micro silicic acid by utilizing aluminum-rich clay is characterized by comprising the following steps:

step 1: mixing the aluminum-rich clay and the auxiliary agent, and grinding to 100-300 meshes to obtain a mixed raw material;

step 2: roasting the mixed raw material obtained in the step 1 to obtain roasted clinker;

and step 3: placing the roasted clinker obtained in the step 2 in water, reacting, and filtering and separating to obtain a water leaching solution and water leaching slag;

and 4, step 4: adding sodium aluminate or sodium silicate into the water leaching slag to adjust the concentration of the sodium aluminate and the concentration of the sodium silicate in the water leaching solution obtained in the step 3, aging for a certain time, and filtering to obtain filter residue of the sodium aluminosilicate;

and 5: adding sulfuric acid into the sodium aluminosilicate obtained in the step 4, mixing and stirring, performing secondary aging, and then filtering to obtain a mixed solution of aluminum sulfate and sodium sulfate, wherein filter residues contain fine silicic acid;

step 6: evaporating and crystallizing the mixed solution of the aluminum sulfate and the sodium sulfate obtained in the step 5, and filtering to obtain a mixture of the aluminum sulfate and the sodium sulfate;

and 7: slowly adding Ca (OH) into the aluminum sulfate and the sodium sulfate obtained in the step 6₂And adjusting the pH value of the solution to 3-5, and filtering and separating to obtain the aluminum sulfate water purifying agent.

2. The method of claim 1, wherein in step 1, the adjuvant is sodium hydroxide or sodium carbonate or potassium hydroxide.

3. The method of claim 1, wherein in step 1, the aluminum-rich clay and the auxiliary agent are mixed in a mass ratio of 1: 0.85 to 1.5.

4. The method of claim 1, wherein in the step 2, the roasting temperature is 600 to 900 ℃ and the roasting time is 15 to 60 min.

5. The method according to claim 1, wherein in the step 3, the addition amount of the roasted clinker and water is 1: 5-15 by solid-liquid mass ratio, and the reaction time is 5-30 min.

6. The method of claim 1, wherein in step 4, sodium aluminate or sodium silicate is added in an amount such that the concentration of the sodium aluminate and sodium silicate species in the resulting aqueous leach solution is equal.

7. The method of claim 1, wherein in the step 4, the aging is performed at a temperature of between room temperature and 90 ℃ for 0.5 to 10 hours.

8. The method according to claim 1, wherein in the step 5, the concentration of sulfuric acid is preferably 1-6 mol/L, and the sulfuric acid is added according to a solid-liquid mass ratio of 1: 5-15; the temperature of the secondary aging is 25-100 ℃, and the time of the secondary aging is 0.5-4 h.

9. The method according to claim 1, wherein in step 6, the mixed solution is evaporated until the solution becomes 30 to 50% of the volume of the original mixed solution, and the evaporation is stopped.

10. The method of claim 1, wherein in step 7, the Ca (OH)₂The mass fraction of the solution is 10-40%.

Technical Field

The invention relates to a method for preparing an aluminum sulfate water purifying agent and co-producing fine silicic acid by utilizing aluminum-rich clay, belonging to the technical field of metallurgy and mineral product utilization.

Background

The water purifying agent is a chemical which can react with other impurities in water when being put into the water. Mainly plays the role of water purification. The commonly used water purifying agents include polyaluminium chloride, polyaluminium ferric chloride, basic aluminium chloride, polyacrylamide, ferrous sulfate, aluminium sulfate, polyferric sulfate and the like.

The aluminum sulfate is a novel, high-quality and high-efficiency ferric salt inorganic polymeric flocculant, has excellent water purification effect and good water quality, does not contain harmful substances such as aluminum, chlorine, heavy metal ions and the like, does not have the water phase transfer of iron ions, and is non-toxic, harmless, safe and reliable. The aluminum sulfate has wide application. The sizing agent is used as a paper sizing agent in the paper industry to enhance the water resistance and seepage resistance of paper; after being dissolved in water, the water coagulant can lead fine particles and natural colloidal particles in the water to be coagulated into large floccules, thereby being removed from the water, thus being used as a coagulant for water supply and waste water; in the fire-fighting industry, the foam extinguishing agent is formed by the foam extinguishing agent, baking soda and a foaming agent; in the fuel industry, it is used as a precipitant in the production of chrome yellow and lake dyes and at the same time as a fixing and filling agent.

In the prior art, aluminum-silicon clay is directly used as an adsorbent, but the adsorbent contains more heavy metal ions and is easy to cause heavy metal pollution. How to fully utilize the aluminum-silicon clay is not reported yet for preparing the aluminum sulfate water purifying agent. The invention provides a new method for preparing an aluminum sulfate water purifying agent from aluminum-silicon clay, and opens up a new way for utilizing aluminum-rich clay.

Disclosure of Invention

The invention provides a method for preparing an aluminum sulfate water purifying agent and co-producing fine silicic acid by utilizing aluminum-rich clay, which separates and extracts aluminum in the aluminum-rich clay and converts the aluminum into an aluminum sulfate water purifying agent product, thereby realizing the utilization of the aluminum in the aluminum-rich clay.

In order to achieve the purpose, the invention adopts the main technical scheme that:

a method for preparing an aluminum sulfate water purifying agent and coproducing micro silicic acid by utilizing aluminum-rich clay comprises the following steps:

step 1: mixing the aluminum-rich clay and the auxiliary agent, and grinding to 100-300 meshes to obtain a mixed raw material;

step 2: roasting the mixed raw material obtained in the step 1 to obtain roasted clinker;

and step 3: placing the roasted clinker obtained in the step 2 in water, reacting, and filtering and separating to obtain a water leaching solution and water leaching slag;

and 4, step 4: adding sodium aluminate or sodium silicate into the water leaching slag to adjust the concentration of the sodium aluminate and the concentration of the sodium silicate in the water leaching solution obtained in the step 3, aging for a certain time, and filtering to obtain filter residue of the sodium aluminosilicate;

and 5: adding sulfuric acid into the sodium aluminosilicate obtained in the step 4, mixing and stirring, performing secondary aging, and then filtering to obtain filter residues containing micro silicic acid, wherein the filtrate is a mixed solution of aluminum sulfate and sodium sulfate;

step 6: evaporating and crystallizing the mixed solution of the aluminum sulfate and the sodium sulfate obtained in the step 5, and filtering to obtain a mixture of the aluminum sulfate and the sodium sulfate;

and 7: slowly adding Ca (OH) into the aluminum sulfate and the sodium sulfate obtained in the step 6₂And adjusting the pH value of the solution to 3-5, and filtering and separating to obtain the aluminum sulfate water purifying agent.

The method as described above, preferably, in step 1, the auxiliary agent is sodium hydroxide or sodium carbonate or potassium hydroxide.

The method as described above, preferably, in step 1, the aluminum-rich clay and the auxiliary agent are mixed in a mass ratio of 1: 0.85 to 1.5.

In the method, preferably, in the step 2, the roasting temperature is 600-900 ℃, and the roasting time is 15-60 min.

In the method, in step 3, the addition amount of the calcined clinker and water is preferably 1:5 to 15 by solid-liquid mass ratio, and the reaction time is preferably 5 to 30 min.

In the method as described above, preferably, in step 4, sodium aluminate or sodium silicate is added in an amount such that the amount concentrations of the sodium aluminate and sodium silicate substances in the resulting aqueous leachate are equal.

In the method, preferably, in the step 4, the aging is carried out for 0.5-10 h at the temperature of normal temperature-90 ℃. Further, it is preferable that the aging temperature is 40 to 90 ℃.

In the method, preferably, in the step 5, the concentration of the sulfuric acid is preferably 1-6 mol/L, and the sulfuric acid is added according to the solid-liquid mass ratio of 1: 5-15; the temperature of the secondary aging is 25-100 ℃, and the time of the secondary aging is 0.5-4 h.

Further, preferably, the secondary aging temperature is 80-100 ℃, and the secondary aging time is 0.5-3 h.

In the method described above, preferably, in step 6, the mixed solution is evaporated until the solution becomes 30 to 50% of the volume of the original mixed solution, and the evaporation is stopped.

The method as described above, preferably, in step 7, the Ca (OH)₂The mass fraction of the solution is 10-40%.

(III) advantageous effects

The invention has the beneficial effects that:

according to the method for preparing the aluminum sulfate water purifying agent and coproducing the micro silicic acid by using the aluminum-rich clay, provided by the invention, the aluminum in the aluminum-rich clay can be separated and extracted and converted into the aluminum sulfate water purifying agent product by combined step-by-step dissolution of activated roasting and water acid, and meanwhile, silicon is converted into the micro silicic acid, so that the elements of silicon and aluminum in the aluminum-rich clay are extracted and utilized to a great extent, and the economic benefit is effectively improved.

The method for preparing the aluminum sulfate water purifying agent and co-producing the micro silicic acid by utilizing the aluminum-rich clay has the advantages of simple process, no special requirements on equipment, low energy consumption, good controllability of process parameters, low cost and the like, and opens up a new way for effectively extracting aluminum from the aluminum-rich clay.

Drawings

FIG. 1 is a schematic flow diagram of the process of the present invention.

Detailed Description

The invention provides a method for preparing an aluminum sulfate water purifying agent and co-producing micro silicic acid by utilizing aluminum-rich clay, which has a flow schematic diagram shown in figure 1 and specifically comprises the following steps:

step 1: mixing the aluminum-rich clay and the auxiliary agent according to the mass ratio of 1: 0.85 to 1.5, and grinding to 100 to 300 meshes to obtain the mixed raw material.

Preferably, the auxiliary agent is alkali, and can be sodium hydroxide or sodium carbonate or potassium hydroxide.

Step 2: and (3) roasting the mixed raw material obtained in the step (1) at the temperature of 600-900 ℃ for a certain time to obtain roasted clinker.

In the step, under the high-temperature roasting, the reaction mainly occurs in that alumina and alkali generate meta-aluminate, SiO₂Formation of silicates with alkali (NaOH for example):

Al₂O₃+2NaOH＝2NaAlO₂+H₂O

SiO₂+2NaOH＝Na₂SiO₃+H₂O

a large number of experimental researches show that the roasting time is preferably 15-60 min, the time is too short and is shorter than 15min, the reaction is insufficient, the aluminum or silicon element cannot be completely reacted, and the energy is excessively consumed and wasted if the time is too long and exceeds 60 min.

And step 3: and (3) placing the roasted clinker obtained in the step (2) into water, reacting for 5-30 min at normal temperature-90 ℃ according to a certain liquid-solid ratio, and filtering and separating to obtain a water leaching solution and water leaching slag.

And 4, step 4: and (3) adjusting the concentrations of sodium aluminate and sodium silicate in the water extract obtained in the step (3) by adding sodium aluminate or sodium silicate, aging for a certain time (0.5-10 h) at a certain temperature of between normal temperature and 90 ℃ (preferably between 40 and 90 ℃), and filtering to obtain the sodium aluminosilicate.

The reaction principle of the step is as follows:

Na₂SiO₃+NaAlO₂+H₂O＝NaAlSiO₄↓+2NaOH；

the added sodium aluminate or sodium silicate is the amount which enables the aluminum element and the silicon element in the aluminum-rich clay to be equal according to the amount of the substances, so that the aluminum or the silicon is completely converted into the sodium aluminosilicate.

And 5: mixing and stirring the sodium aluminosilicate obtained in the step 4 and sulfuric acid according to a solid-liquid mass ratio of 1: 5-1: 15 for 1-5 min, performing secondary aging at 25-100 ℃ for 0.5-4 h to obtain a mixed solution of fine silicic acid, aluminum sulfate and sodium sulfate, filtering, wherein filter residues contain fine silicic acid, and a filtrate is a mixed solution of aluminum sulfate and sodium sulfate.

The reaction principle of the step is as follows:

2NaAlSiO₄+4H₂SO₄＝2H₄SiO₄↓+Al₂(SO₄)₃+Na₂SO₄；

a large number of experimental researches show that the concentration of sulfuric acid is preferably 1-6 mol/L, the sodium aluminosilicate cannot be completely reacted due to the fact that the concentration of the sulfuric acid is too low, the concentration is too high, and the operation is unsafe, so that the sulfuric acid with the concentration of 1-6 mol/L is preferably selected, the temperature of secondary aging is preferably 80-100 ℃, the time of secondary aging is preferably 0.5-3 h, and the aging temperature is too low, so that the reaction of silicic acid is not facilitated.

Step 6: and (4) evaporating and crystallizing the mixed solution of the aluminum sulfate and the sodium sulfate obtained in the step (5), and filtering to obtain a mixture of the aluminum sulfate and the sodium sulfate.

Research shows that when the mixed solution of aluminum sulfate and sodium sulfate is evaporated to 30-50% of the original volume, a large amount of solid solute is separated out and is detected to be a mixture of aluminum sulfate and sodium sulfate. When the mixed solution is completely crystallized to obtain aluminum sulfate and sodium sulfate, the recovery rate can reach more than 99 percent, but the time consumption is long, and when the mixed solution is generally evaporated to 30 to 50 percent of the original volume, most of the aluminum sulfate and the sodium sulfate can be recovered, so that the evaporation can be stopped for saving the cost and energy.

And 7: slowly adding Ca (OH) into the aluminum sulfate and the sodium sulfate obtained in the step 6₂And adjusting the pH value of the solution to 3-5, and filtering and separating to obtain the aluminum sulfate water purifying agent.

Added Ca (OH)₂The concentration of (A) is preferably 10-40%, when the concentration is too high, a large amount of calcium-containing precipitates are generated, and when the concentration is too low, the aluminum cannot be completely reacted. Ca (OH)₂Stopping adding Ca (OH) when the pH value of the solution reaches 3-5₂When the pH value reaches 3-5, aluminum sulfate can be completely precipitated. The reaction principle of the step is as follows:

2Al₂(SO₄)₃+2nH₂O＝2Al₂(OH)_n(SO₄)_3-n/2+nH₂SO₄

m[Al₂(OH)_n(SO₄)_3-n/2]＝[Al₂(OH)_n(SO₄)_3-n/2]_m。

for a better understanding of the present invention, reference will now be made in detail to the present invention by way of specific embodiments thereof.

Example 1

The aluminum in the aluminum-rich clay of this embodiment is Al₂O₃Calculated as 36.03 percent, the silicon is SiO₂42.85% of iron in terms of Fe₂O₃The content is 5.38%. The method comprises the following specific steps:

step 1: mixing the aluminum-rich clay and sodium hydroxide according to the mass ratio of 1:1, mixing and grinding to 150 meshes to obtain a mixed raw material;

step 2: roasting the mixed raw material obtained in the step 1 at 600 ℃ for 20min to obtain roasted clinker;

and step 3: putting the roasted clinker obtained in the step 2 into water, adding water according to a liquid-solid ratio of 5:1, reacting for 30min at normal temperature, and filtering and separating to obtain a water leaching solution and water leaching residues;

and 4, step 4: adding sodium aluminate and adjusting the concentration of the sodium aluminate and the sodium silicate in the water extract obtained in the step 3 to ensure that the quantity concentration of the sodium aluminate and the sodium silicate in the solution is equal, aging for 8 hours at the temperature of 40 ℃, and filtering to obtain the sodium aluminosilicate, wherein the recovery rate is 96.56%;

and 5: mixing and stirring the sodium aluminosilicate obtained in the step 4 and 2mol/L sulfuric acid according to a solid-liquid mass ratio of 1:15 for 5min, then performing secondary aging for 0.5h at the temperature of 100 ℃, and filtering to obtain filter residue of fine silicic acid and a mixed solution of aluminum sulfate and sodium sulfate;

step 6: evaporating and crystallizing the mixed solution of the aluminum sulfate and the sodium sulfate obtained in the step 5 to ensure that the volume of the evaporated solution is 30 percent of that of the original solution, and filtering to obtain the aluminum sulfate and the sodium sulfate, wherein the recovery rates are 81.26 percent and 80.77 percent respectively;

and 7: slowly adding 10 percent Ca (OH) by mass into the aluminum sulfate obtained in the step 6₂Adjusting the pH value of the solution to 3.5, and filtering and separating to obtain the aluminum sulfate water purifying agent.

Example 2

The aluminum in the aluminum-rich clay of this embodiment is Al₂O₃Calculated as 36.03 percent, the silicon is SiO₂42.85% of iron in terms of Fe₂O₃The content is 5.38%. The method comprises the following specific steps:

step 1: mixing the aluminum-rich clay and sodium carbonate according to the mass ratio of 1: 1.5, mixing and grinding to 150 meshes to obtain mixed raw materials;

step 2: roasting the mixed raw material obtained in the step 1 at 900 ℃ for 20min to obtain roasted clinker;

and step 3: placing the roasted clinker obtained in the step 2 in water, reacting for 30min at normal temperature according to a liquid-solid ratio of 5:1, and filtering and separating to obtain a water leaching solution and water leaching residues;

and 4, step 4: adding sodium aluminate into the water extract obtained in the step 3, wherein the adding amount is equal to the amount concentration of substances of the sodium aluminate and the sodium silicate in the obtained water extract, aging for 2 hours at the temperature of 90 ℃, and filtering to obtain the sodium aluminosilicate, wherein the recovery rate is 94.93%;

and 5: mixing and stirring the sodium aluminosilicate obtained in the step 4 and 4mol/L sulfuric acid according to the solid-liquid mass ratio of 1:10 for 2min, then performing secondary aging for 0.5h at the temperature of 100 ℃, and filtering to obtain a mixed solution of fine silicic acid, aluminum sulfate and sodium sulfate;

step 6: evaporating and crystallizing the mixed solution of the aluminum sulfate and the sodium sulfate obtained in the step 5 to ensure that the volume of the evaporated solution is 40 percent of that of the original solution, and filtering to obtain the aluminum sulfate and the sodium sulfate, wherein the recovery rates are 80.31 percent and 75.44 percent respectively;

and 7: slowly adding 30 mass percent of Ca (OH) into the aluminum sulfate obtained in the step 6₂Adjusting the pH value of the solution to 5, and filtering and separating to obtain the aluminum sulfate water purifying agent.

Example 3

The aluminum in the aluminum-rich clay of this embodiment is Al₂O₃Calculated as 36.03 percent, the silicon is SiO₂42.85% of iron in terms of Fe₂O₃The content is 5.38%. The method comprises the following specific steps:

step 1: mixing the aluminum-rich clay and sodium hydroxide according to the mass ratio of 1: 1.3, mixing and grinding to 150 meshes to obtain mixed raw materials;

step 2: roasting the mixed raw material obtained in the step 1 at 800 ℃ for 30min to obtain roasted clinker;

and step 3: putting the roasted clinker obtained in the step 2 into water according to the liquid-solid ratio of 10:1, reacting for 45min at normal temperature, and filtering and separating to obtain water extract and water extract slag;

and 4, step 4: adding sodium aluminate into the water extract obtained in the step 3, wherein the adding amount is equal to the amount and concentration of substances of the sodium aluminate and the sodium silicate in the obtained water extract, aging for 10 hours at the temperature of 60 ℃, and filtering to obtain the sodium aluminosilicate, wherein the recovery rate is 98.93%;

and 5: mixing and stirring the sodium aluminosilicate obtained in the step 4 and 2mol/L sulfuric acid according to a solid-liquid mass ratio of 1:8 for 2min, then performing secondary aging at the temperature of 90 ℃ for 3h, and filtering to obtain filter residue of fine silicic acid and a mixed solution of aluminum sulfate and sodium sulfate;

step 6: evaporating and crystallizing the mixed solution of the aluminum sulfate and the sodium sulfate obtained in the step 5 to ensure that the volume of the evaporated solution is 50 percent of that of the original solution, and filtering to obtain the aluminum sulfate and the sodium sulfate, wherein the recovery rates are 90.45 percent and 85.37 percent respectively;

and 7: slowly adding 30 mass percent of Ca (OH) into the aluminum sulfate obtained in the step 6₂Adjusting the pH value of the solution to 4.5, and filtering and separating to obtain the aluminum sulfate water purifying agent.

Compared with the adsorbent prepared by directly preparing clay in the prior art, the method disclosed by the invention can be used for fully recovering the aluminum component in the aluminum-enriched clay and also can be used for recovering components such as silicon, sodium and the like, and the adsorbent prepared by directly preparing the clay contains more heavy metal ions.

Compared with the method for preparing the water purifying agent by using the fly ash, the method has the advantages of low cost (the raw materials in the method can be recycled), environmental protection (a large amount of acidic wastewater needs to be discharged in the preparation of the water purifying agent by using the fly ash), good controllability of process parameters (the method is simple in process and easy to operate), and high economic benefit (products obtained by the method are high value-added products).

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in other forms, and any person skilled in the art can change or modify the technical content disclosed above into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention are within the protection scope of the technical solution of the present invention.