CN111111929B

CN111111929B - Method for separating calcium carbonate by alkali residue pretreatment

Info

Publication number: CN111111929B
Application number: CN201911390851.0A
Authority: CN
Inventors: 郭强; 贾志军; 刘国振
Original assignee: Hebei Zhongke Tongchuang Technology Development Co ltd
Current assignee: Hebei Zhongke Tongchuang Technology Development Co ltd
Priority date: 2019-12-30
Filing date: 2019-12-30
Publication date: 2021-10-15
Anticipated expiration: 2039-12-30
Also published as: CN111111929A

Abstract

The invention relates to the technical field of solid waste treatment, and provides a method for separating calcium carbonate by alkali residue pretreatment, wherein the alkali residue is subjected to water leaching and then filtered to obtain dechlorinated alkali residue; the alkaline residue is generated in the production of soda by an ammonia-soda process; and mixing the dechlorinated alkaline residues with water to prepare slurry, adjusting the pH value to 9.5-10.5, sequentially adding an inhibitor and a collecting agent, and performing flotation to obtain calcium carbonate. The method provided by the invention has the advantages of simple process and easy operation, and can effectively separate calcium carbonate from the alkaline residue and improve the yield of the calcium carbonate.

Description

Method for separating calcium carbonate by alkali residue pretreatment

Technical Field

The invention relates to the technical field of solid waste treatment, in particular to a method for separating calcium carbonate by alkaline residue pretreatment.

Background

A large amount of alkaline residue can be generated in the industrial process of producing the soda by the ammonia-soda process, and the main components of the alkaline residue comprise calcium salt waste residues such as calcium carbonate, calcium sulfate, calcium chloride and the like, and also contain components such as magnesium hydroxide, chloride, a small amount of sulfur dioxide and the like; in the actual production process, due to technical limitation or the aim of reducing the working procedures and saving the cost, most of alkaline residues generated by enterprises are treated in a surface accumulation mode, so that a 'white sea' is formed in an accumulation area, and the pollution is caused to the surrounding environment. Therefore, how to effectively utilize the alkaline residue and apply the alkaline residue to industrial production becomes a problem which needs to be solved urgently at present.

At present, aiming at different effective components and different purposes of soda ash residue, the recovery mode of soda residue can be roughly divided into: sea reclamation, alkali residue mortar modifier preparation, marine product cultivation and water quality modifier preparation, alkali residue building material preparation, alkali residue compound fertilizer preparation, alkali residue flue gas desulfurizer preparation and the like, see "Wangzui et al, the development and utilization progress of waste residue in ammonia-soda process soda production [ J ] soda industry, 2005 (6). Calcium carbonate is used as an important industrial raw material and has wide industrial application, calcium salt is one of main raw materials for preparing calcium carbonate, and if adverse effects (such as corrosion of chloride and mixing of magnesium salt) of other substances can be avoided, the calcium salt in the alkaline residue is effectively converted into the calcium carbonate, so that the calcium carbonate has good environmental benefit and can add great economic benefit.

At present, researches on the industrial application of the alkaline residue mainly stay in the removal of chloride ions and the reuse of a mixed alkaline residue composition after chlorine removal, and no relevant documents report on how to further separate the alkaline residue to obtain calcium carbonate and improve the product yield.

Disclosure of Invention

In view of the above, the present invention aims to provide a method for separating calcium carbonate by alkaline residue pretreatment. The method provided by the invention can effectively separate calcium carbonate from the alkaline residue and improve the yield of the calcium carbonate.

In order to achieve the above purpose, the invention provides the following technical scheme:

the invention provides a method for separating calcium carbonate by alkaline residue pretreatment, which comprises the following steps:

soaking the caustic sludge in water, and filtering to obtain dechlorinated caustic sludge; the alkaline residue is generated in the production of soda by an ammonia-soda process;

and mixing the dechlorinated alkaline residues with water to prepare slurry, adjusting the pH value to 9.5-10.5, sequentially adding an inhibitor and a collecting agent, and performing flotation to obtain calcium carbonate.

Preferably, the alkali residue is subjected to water leaching and then is subjected to a crushing process, and the crushed alkali residue is powdery.

Preferably, the mass ratio of the particles with the fineness of less than 200 meshes in the powdery alkaline residue is 60-70%.

Preferably, the water immersion is carried out under stirring conditions, and the stirring time is preferably 10-20 min.

Preferably, the mass ratio of the inhibitor to collector is 2: 1.

Preferably, the inhibitor comprises sodium hexametaphosphate and/or water glass.

Preferably, the collector comprises sodium oleate and/or oleic acid.

Preferably, the time interval between the addition of the inhibitor and the collector is 3-5 min.

Preferably, the flotation comprises the steps of stirring, aeration and froth scraping.

Preferably, the floating product after flotation is calcium carbonate.

The invention provides a method for separating calcium carbonate by pretreating alkaline residue, which comprises the steps of soaking the alkaline residue in water, and filtering to obtain dechlorinated alkaline residue; the alkaline residue is generated in the production of soda by an ammonia-soda process; and mixing the dechlorinated alkaline residues with water to prepare slurry, adjusting the pH value to 9.5-10.5, sequentially adding an inhibitor and a collecting agent, and performing flotation to obtain calcium carbonate. According to the invention, the alkaline residue is subjected to water leaching, chlorine-containing salts such as sodium chloride and potassium chloride in the alkaline residue can be dissolved in water to form water-soluble salts, the dechlorinated alkaline residue is obtained after filtration and removal, the hydrophobic difference between calcium carbonate and other impurities can be increased by adding the inhibitor under the pH condition, and calcium carbonate particles can adhere to bubbles to float upwards in the flotation process to obtain the final product calcium carbonate. The alkaline residue pretreatment separation method provided by the invention is simple in process and easy to operate, and the yield of calcium carbonate reaches 26.79% -28.54%, so that the method is suitable for industrial production.

Drawings

FIG. 1 is a process flow diagram for the pretreatment and separation of calcium carbonate from caustic sludge in example 1 of the present invention.

Detailed Description

The invention carries out water leaching on the caustic sludge and then filters the caustic sludge to obtain dechlorinated caustic sludge.

In the invention, the caustic sludge is waste residue generated in the production of soda ash by an ammonia-soda process. In the invention, the waste residue generated in the production of soda ash by an ammonia-soda process mainly comprises calcium salt (about 70 wt%), and other components comprise magnesium hydroxide, sodium chloride, potassium chloride, calcium sulfate and other substances; in order to improve the separation effect of calcium carbonate in the subsequent process, the chloride in the alkaline residue needs to be removed, and the inclusion of magnesium salt impurities needs to be avoided.

In the invention, the water immersion temperature is preferably 20-40 ℃, and the liquid-solid ratio of the water immersion is preferably 2-3: 1; in the invention, the water immersion is preferably carried out under stirring conditions, and the stirring time is preferably 10-20 min, and more preferably 15 min. In the invention, the purpose of water leaching is to dissolve sodium chloride and potassium chloride in the caustic sludge to form water-soluble chloride salt, and the water-soluble chloride salt is further removed through a subsequent filtering step to achieve dechlorination effect.

In the invention, before the alkaline residue is subjected to water leaching, a crushing process is preferably further included, and the crushed alkaline residue is powdery; in the present invention, the crushing apparatus is preferably a small crusher. In the invention, the mass ratio of the particles with the fineness of less than 200 meshes in the powdery alkaline residue is 60-70%, and more preferably 65.3%. The invention aims to reduce the granularity of the alkaline residue, reduce the fineness distribution deviation and further improve the yield of calcium carbonate products in the subsequent flotation process by crushing the alkaline residue before water leaching.

The filtering scheme is not particularly limited, and the conventional filtering scheme in the field is adopted, and the chlorine-containing aqueous solution can be removed by filtering the alkali residue after water leaching to obtain dechlorinated alkali residue.

After the dechlorination alkaline residue is obtained, the dechlorination alkaline residue and water are mixed to prepare slurry, the pH value is adjusted to 9.5-10.5, an inhibitor and a collecting agent are sequentially added, and calcium carbonate is obtained through flotation.

The preparation method of the slurry is not particularly limited, and a conventional method for preparing flotation slurry in the field is adopted, and the dechlorinated alkali residues are preferably dispersed in water and stirred to prepare the slurry; in the invention, the mass concentration of the dechlorinated alkali residues in the slurry is preferably 35-45%.

In the present invention, the pH adjusting agent is preferably hydrochloric acid; under the alkaline condition that the pH value is 9.5-10.5, the floatability of calcite in the dechlorinated alkaline residues is good under the condition of the pH value, and the inhibiting effect of the inhibitor on other components is the best within the pH range.

In the present invention, the mass ratio of the inhibitor to collector is preferably 2: 1; in the present invention, the inhibitor preferably comprises sodium hexametaphosphate and/or water glass; sodium hexametaphosphate is further preferred in the embodiment of the invention, and the addition amount of the sodium hexametaphosphate is preferably 100 g/t; in the invention, the sodium hexametaphosphate is a linear chain compound with the chain length of about 20-100 PO^-3When the calcium carbonate is adsorbed on the surface of the mineral, the steric hindrance effect among particles is intensified, the floating rate of the calcium carbonate in the flotation process is increased, the floatability difference between the calcium carbonate and the magnesium hydroxide is increased to the maximum extent, and the yield of the flotation product is increased.

In the present invention, the collector preferably comprises sodium oleate and/or oleic acid; further preferred in the specific embodiment of the present invention is sodium oleate, the addition amount of said sodium oleate is preferably 50 g/t; in the invention, the appearance of the sodium oleate is light yellow to yellow powder, belongs to an anionic surfactant, is a compound consisting of a hydrophobic group and a hydrophilic group, has excellent emulsifying power, penetrability and detergency, has good solubility in hot water, can be dissolved in water, and has alkaline aqueous solution.

In the invention, the time interval between the addition of the inhibitor and the collector is preferably 3-5 min, and more preferably 5 min.

In the present invention, the flotation preferably comprises the steps of stirring, aeration and froth scraping; in the invention, the stirring time is preferably 3-5 min; and the foam scraping time is preferably 5-10 min, the floating product obtained after the step is finished is calcium carbonate, the obtained bottom product is a flotation solution, and the flotation solution is used for recycling.

The method for separating calcium carbonate by alkaline residue pretreatment according to the present invention will be described in detail with reference to the following examples, but they should not be construed as limiting the scope of the present invention.

Example 1

S1: smashing the caustic sludge into powder by using a small crusher, wherein the mass of particles with the fineness of less than 200 meshes accounts for 65.3%;

s2: soaking powdery alkaline residue in water in a flotation tank, stirring for 15min, and filtering to remove soluble salts such as sodium chloride and potassium chloride to obtain dechlorinated alkaline residue;

s3: mixing the dechlorinated alkali residues with water, adding the mixture into a flotation tank to prepare slurry, adding hydrochloric acid to adjust the pH value of the slurry to 10, and stirring for 3 min;

s4: adding 100g/t of inhibitor sodium hexametaphosphate, and stirring for 3 min;

s5: adding 50g/t of collecting agent sodium oleate for flotation: stirring for 3min, aerating, and scraping for 5min to obtain calcium carbonate as floating product in 26.79% yield.

FIG. 1 is a process flow diagram of example 1, which is to crush caustic sludge, perform water leaching, and obtain soluble chloride salt and dechlorinated caustic sludge by stirring and filtering; the dechlorinated alkali residues are compounded with water in a flotation tank to form slurry, hydrochloric acid is used for adjusting the pH value of the slurry, inhibitor sodium hexametaphosphate and collecting agent sodium oleate are sequentially added, and then flotation is carried out to obtain floating product calcium carbonate and flotation residues.

Example 2

S1: mashing the caustic sludge into powder by using a small crusher, wherein the mass of particles with the fineness of less than 200 meshes accounts for 69.5%;

s2: soaking powdery alkaline residue in water in a flotation tank, stirring for 15min, filtering to remove soluble salts such as sodium chloride and potassium chloride to obtain dechlorinated alkaline residue;

s3: mixing the dechlorinated alkali residues with water, adding the mixture into a flotation tank to prepare slurry, adding hydrochloric acid to adjust the pH value of the slurry to 9.5, and stirring for 3 min;

s4: adding inhibitor sodium hexametaphosphate 1000g/t, and stirring for 3 min;

s5: adding 50g/t of collecting agent sodium oleate for flotation: stirring for 3min, aerating, and scraping for 5min to obtain calcium carbonate as floating product in 28.54% yield.

Example 3

S1: smashing the caustic sludge into powder by using a small crusher, wherein the particles with the fineness of less than 200 meshes account for 61.4 percent;

s2: soaking powdery alkaline residue in water in a flotation tank, stirring for 20min, filtering to remove soluble salts such as sodium chloride and potassium chloride to obtain dechlorinated alkaline residue;

s3: mixing the dechlorinated alkali residues with water, adding the mixture into a flotation tank to prepare slurry, adding hydrochloric acid to adjust the pH value of the slurry to 10.5, and stirring for 5 min;

s4: adding 100g/t of inhibitor water glass, and stirring for 3 min;

s5: adding 50g/t of collecting agent oleic acid for flotation: stirring for 3min, aerating, and scraping for 5min to obtain calcium carbonate as floating product in 23.45% yield.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. The method for separating calcium carbonate by pretreating alkaline residue is characterized by comprising the following steps:

mixing the dechlorinated alkaline residues with water to prepare slurry, adjusting the pH value to 9.5-10.5, sequentially adding an inhibitor and a collecting agent, and performing flotation to obtain calcium carbonate; the collector comprises sodium oleate and/or oleic acid; the inhibitor comprises sodium hexametaphosphate and/or water glass; the mass ratio of the inhibitor to the collector is 2: 1.

2. The method as claimed in claim 1, wherein the caustic sludge before water leaching further comprises a pulverization process, and the pulverized caustic sludge is in powder form.

3. The method according to claim 2, wherein the mass ratio of the particles with fineness less than 200 meshes in the powdery alkaline residue is 60-70%.

4. The method according to claim 1, wherein the water immersion is performed under stirring for 10 to 20 min.

5. The method according to claim 1, wherein the time interval between the addition of the inhibitor and the collector is 3-5 min.

6. The method according to claim 1, characterized in that the flotation comprises the steps of stirring, aeration and froth scraping.

7. The method of claim 1, wherein the post-flotation product is calcium carbonate.