CN103482655B - Lime-sodium sulfate-carbon dioxide method used for purifying calcium chloride type bittern - Google Patents

Abstract

The invention discloses a lime-sodium sulfate-carbon dioxide method used for purifying calcium chloride type bittern. The lime-sodium sulfate-carbon dioxide method comprises following steps: (A) preparation of lime milk; (B) preparation of sodium sulfate suspension; (C) preparation of a first order flocculating agent solution; (D) first-order reaction; (E) preparation of carbon dioxide; (F) preparation of a second order flocculating agent solution; and (G) second-order reaction. According to the lime-sodium sulfate-carbon dioxide method, quicklime and carbon dioxide in flue gas are used for removing Ca<2+> and Mg <2-> in calcium chloride type bittern, so as to reduce purification cost of enterprises producing calcium chloride type bittern, reduce carbon dioxide discharge capacity of thermal power plants or boiler plants, and provide novel technological methods for purification of calcium chloride type bittern.

Description

Lime-sodium sulfate-carbon dioxide process chloride-calcium type bittern purifying technique

Technical field

The invention belongs to chloride-calcium type brine purifying technique, particularly lime-sodium sulfate-carbon dioxide process removes Ca in chloride-calcium type bittern ²⁺and Mg ²⁺method.

Background technology

In adopt chloride-calcium type bittern to carry out chloride-calcium type bittern that salt making enterprises adopts, except H ₂outside O, the main NaCl(content range that contains is between 250 ~ 310 g/l), secondly containing CaCl ₂(content range is between 0 ~ 20 g/l), minor compound are CaSO ₄(content range is all between 0 ~ 3g/l) and MgCl ₂(content range is all between 0 ~ 5g/l).Ca in chloride-calcium type bittern ²⁺caSO can be generated in evaporation Salt Production process ₄affect quality product, and Mg ²⁺and Ca ²⁺can improve the boiling point of solution in evaporative process, not only reduce heat transfer efficiency significantly, also cause heating tube to clean frequent, the effective production time of influential system, affects quality product simultaneously.

Energy-saving and emission-reduction have risen to a fundamental state policy of many national sustainable developments, and energy-saving and emission-reduction from now on require can be more and more higher.By bittern purifying technique, reduce the Ca in refining bittern ²⁺, Mg ²⁺concentration, effectively can address this problem, ensure quality product, improve system heat transfer performance, extend effective production time.

Traditional chloride-calcium type Brine Chemistry purifying method adopts the Mg in " caustic soda " method removal chloride-calcium type bittern ²⁺, cause evaporation salt manufacturing can only adopt " gypsum seed method ", the Ca of enrichment ²⁺not only by outer row's salt-making mother liquor, waste resource but also waste the heat energy that salt-making mother liquor takes away, and quality product is low, the brush tank cycle is short.Simultaneously because domestic caustic soda price significantly rises in recent years, thus increase substantially bittern purifying cost.Therefore, how effectively reducing production cost, improve the quality of products, extend manufacture cycle is the current existence important business faced of enterprise.

Summary of the invention

The present invention aims to provide the Ca in a kind of lime-sodium sulfate-carbon dioxide process removal chloride-calcium type bittern ²⁺and Mg ²⁺purifying method.

Technical scheme of the present invention:

Lime-sodium sulfate-carbon dioxide process chloride-calcium type bittern purifying technique, is characterized in that adopting following processing step:

(A) preparation of milk of lime: adopt unslaked lime and chloride-calcium type bittern to carry out chemical reaction and obtain milk of lime, the Ca (OH) in gained solution ₂content is 10% ~ 15%, the solid-state Ca (OH) in suspension ₂≤ 18%;

(B) preparation of sodium sulfate suspension: adopt industrial sulphuric acid sodium and chloride-calcium type bittern to be mixed to get sodium sulfate suspension, Na ₂sO ₄content is 25% ~ 30%;

(C) preparation of one-level flocculant solution: add non-ionic group thing flocculation agent in solution, every cube of chloride-calcium type bittern adds 2 ~ 3g flocculation agent, and in solution, the massfraction of flocculation agent is 0.08% ~ 0.1%;

(D) first order reaction: the chloride-calcium type bittern in first order reaction bucket adds milk of lime under 20 ~ 100r/min mixing speed, and add-on is controlled by pH value, and the scope of pH is 12.3 ~ 12.8; Continue to stir, react and add one-level flocculant solution afterwards in 5 hours; Stop stirring clarification more than 2 hours, first order reaction supernatant liquor proceeds to second order reaction, and first order reaction mud pumps into mud disposal system;

(E) preparation of carbonic acid gas: adopt the stack gas that thermoelectric power station or boiler house produce, CO ₂content is between 10% ~ 12%, and stack gas, by after washing tower washing cooling, is compressed;

(F) preparation of secondary flocculant solution: add anionic group thing flocculation agent in solution, every cube of chloride-calcium type bittern adds 2 ~ 3g flocculation agent, and in solution, the massfraction of flocculation agent is 0.08% ~ 0.1%;

(G) second order reaction: the chloride-calcium type bittern in second order reaction bucket passes into carbonic acid gas under 20 ~ 100r/min mixing speed, and add-on is controlled by pH value, and the scope of pH is between 10.5 ~ 11; Continue stirring and add secondary flocculant solution afterwards in 2 hours; Stop stirring clarification more than 2 hours, the supernatant liquor of second order reaction is just refining bittern, and second order reaction mud pumps into mud disposal system.

Solution described in said process is chloride-calcium type bittern, and described solid sodium sulfate is technical grade Sodium sulfate anhydrous.min(99), and unslaked lime content is CaO >=60%.

Described flocculation agent is group compound, comprises following two kinds:

(1) non-ionic group thing: as Polyacrylamide, polyoxyethylene, polyvinyl alcohol etc.

(2) anionic group thing: as sodium polyacrylate, ammonium polyacrylate etc.

Principle of the present invention:

(1) Ca (OH) is utilized ₂with MgSO ₄there is chemical reaction, generate Mg (OH) ₂flocks.

(2) Ca (OH) is utilized ₂with Na ₂sO ₄there is chemical reaction, generate NaOH.

(3) CO is utilized ₂there is chemical reaction with NaOH, generate Na ₂cO ₃.

(4) Ca is utilized ²⁺with Na ₂cO ₃there is chemical reaction, generate CaCO ₃precipitation.

(5) Mg (OH) is utilized respectively ₂, CaSO ₄and CaCO ₃solubility product in chloride-calcium type bittern, generates Mg (OH) respectively ₂, CaCO ₃and CaSO ₄2H ₂o precipitates.

(6) the adding of flocculation agent, the suspended particulates in solution can be assembled connection and form thick cotton-shaped granule or agglomerate, be convenient to Mg (OH) ₂, CaSO ₄2H ₂o and CaCO ₃sedimentation.

Just the Ca in chloride-calcium type bittern can be removed through above-mentioned purifying method ²⁺and Mg ²⁺, obtained refining bittern, can utilize experiment to carry out mensuration decontamination effect improving.That is: take quantitative different content chloride-calcium type bittern and salt-making mother liquor to be placed in small test device, reaction and sedimentation certain hour, measure the Ca in clear liquid ²⁺, SO ₄ ^2-and Mg ²⁺content.Ca in clear liquid ²⁺and Mg ²⁺content less, decontamination effect improving is better, otherwise then decontamination effect improving is poorer.

Lime-sodium sulfate-carbonic acid gas chloride-calcium type bittern purifying technique is adopted for chloride-calcium type bittern, the stack gas of thermoelectric power station or boiler house discharge can be utilized, the CO2 emissions of thermoelectric power station or boiler house can be reduced.By international " carbon emission amount " method of calculation, reduce discharging 2.493kgCO ₂be equivalent to save 1kg standard coal.By the refining bittern that the inventive method is obtained, can be used for evaporating Salt Production, and evaporate salt producing craft and no longer adopt " gypsum seed " method, the quality product of salt manufacturing workshop gained is high, without outer row's mother liquor, the advantages such as production cycle long and steam consumption is low.Ca in chloride-calcium type bittern ²⁺and Mg ²⁺clearance can reach more than 98%.

Substantive distinguishing features of the present invention and marked improvement are: utilize the Ca in the co 2 removal chloride-calcium type bittern in unslaked lime, sodium sulfate and stack gas ²⁺and Mg ²⁺, reduce purification cost and the steam consumption of Salt Production enterprise, decrease the CO2 emissions of thermoelectric power station or boiler house simultaneously, for chloride-calcium type bittern purifying provides new processing method.

Accompanying drawing explanation

Accompanying drawing 1 is intermittent chlorination calcium type bittern purifying process diagram.

Accompanying drawing 2 is continuous chlorination calcium type bittern purifying process diagram.

Embodiment

Two embodiments are provided below.Intermittent chlorination calcium type bittern purifying technique is identical with parameter with the processing step of continuous chlorination calcium type bittern purifying technique.The difference of intermittent chlorination calcium type bittern purifying technique and continuous chlorination calcium type bittern purifying technique is: intermittent chlorination calcium type bittern purifying technique be by react and clarify be placed on same have in enough large container carry out; And continuous chlorination calcium type bittern purifying technique reaction is placed in an a certain amount of container to carry out, clarification is placed in multiple less container to be carried out.Embodiment 1 adopts the intermittent chlorination calcium type bittern purifying technique of accompanying drawing 1, and embodiment 2 adopts the continuous chlorination calcium type bittern purifying technique of accompanying drawing 2.

Embodiment 1:

Chloride-calcium type bittern composition is: H ₂o:885.7g/l; NaCl:310 g/l; CaCl ₂: 2.56 g/l; CaSO ₄: 1.61g/l; MgCl ₂: 0.23 g/l; Salt manufacturing Workshop Production 10t Industrial Salt, then cleaning shop need process 32.8m ³chloride-calcium type bittern and 27.5m ³salt-making mother liquor, first order reaction first adds the Na of 147.2kg under 20 ~ 100r/min mixing speed ₂sO ₄, then add 56.5kgCaO and continue stirring reaction and add one-level flocculation agent 0.12kg after 5 hours, stop stirring clarification 2 hours, measure the Mg in clear liquid ²⁺0.1ppm and 12.5 is respectively with pH value; One-level clear liquid is proceeded to second order reaction, and second order reaction passes into stack gas 298Nm under 20 ~ 100r/min mixing speed ³, continue to stir, after 2 hours, add secondary flocculation agent 0.12kg, stop stirring clarification 2 hours, measure the Ca in clear liquid ²⁺, Mg ²⁺4ppm, 0.1ppm and 11. Ca are respectively with pH value ²⁺and Mg ²⁺clearance all reaches 99%, and the amount of carbon dioxide quantity discharged simultaneously reduced is equivalent to 16kg and marks coal.

Embodiment 2:

Chloride-calcium type bittern composition is: H ₂o:885.2g/l; NaCl:300 g/l; CaCl ₂: 10.51 g/l; CaSO ₄: 1.91g/l; MgCl ₂: 2.38 g/l; Salt manufacturing Workshop Production 10t Industrial Salt, then cleaning shop need process 33.7m ³chloride-calcium type bittern and 25.6m ³salt-making mother liquor, first order reaction adds the Na of 598.9kg under 20 ~ 100r/min mixing speed ₂sO ₄, then add 99.5kgCaO and ensure more than the 5 hours residence time, proceed to one-level clarifying equipment, add one-level flocculation agent 0.12kg simultaneously, measure the Mg in clear liquid ²⁺0.1ppm and 12.5 is respectively with pH value; The clear liquid of one-level clarifying equipment is proceeded to second order reaction bucket, and second order reaction passes into carbonic acid gas 302Nm under 20 ~ 100r/min continuously stirring rotating speed ³, and ensure more than the 2 hours residence time, proceed to secondary clarifying equipment, add secondary flocculation agent 0.12kg simultaneously, measure the Ca in clear liquid ²⁺, Mg ²⁺4.3ppm, 0.1ppm and 11 are respectively with pH value.Clear liquid in secondary clarifying equipment is just refining bittern, and the body refuse in one-level clarifying equipment and secondary clarifying equipment goes body refuse treatment system.Ca ²⁺and Mg ²⁺clearance all reaches 99%, and the amount of carbon dioxide quantity discharged simultaneously reduced is equivalent to 16kg and marks coal.

Claims (1)

1. lime-sodium sulfate-carbon dioxide process chloride-calcium type bittern purifying technique, is characterized in that adopting following processing step:

(A) preparation of milk of lime: adopt unslaked lime and chloride-calcium type bittern to carry out chemical reaction and obtain milk of lime, the Ca (OH) in gained solution ₂content is 10% ~ 15%, the solid-state Ca (OH) in suspension ₂≤ 18%;

(B) preparation of sodium sulfate suspension: adopt industrial sulphuric acid sodium and chloride-calcium type bittern to be mixed to get sodium sulfate suspension, Na ₂sO ₄content is 25% ~ 30%;

(C) preparation of one-level flocculant solution: add non-ionic group thing flocculation agent in solution, every cube of chloride-calcium type bittern adds 2 ~ 3g flocculation agent, and in solution, the massfraction of flocculation agent is 0.08% ~ 0.1%;

(D) first order reaction: the chloride-calcium type bittern in first order reaction bucket adds milk of lime under 20 ~ 100r/min mixing speed, and add-on is controlled by pH value, and the scope of pH is 12.3 ~ 12.8; Continue to stir, react and add one-level flocculant solution afterwards in 5 hours; Stop stirring clarification more than 2 hours, first order reaction supernatant liquor proceeds to second order reaction, and first order reaction mud pumps into mud disposal system;

(E) preparation of carbonic acid gas: adopt the stack gas that thermoelectric power station or boiler house produce, CO ₂content is between 10% ~ 12%, and stack gas, by after washing tower washing cooling, is compressed;

(F) preparation of secondary flocculant solution: add anionic group thing flocculation agent in solution, every cube of chloride-calcium type bittern adds 2 ~ 3g flocculation agent, and in solution, the massfraction of flocculation agent is 0.08% ~ 0.1%;

(G) second order reaction: the chloride-calcium type bittern in second order reaction bucket passes into carbonic acid gas under 20 ~ 100r/min mixing speed, and add-on is controlled by pH value, and the scope of pH is between 10.5 ~ 11; Continue stirring and add secondary flocculant solution afterwards in 2 hours; Stop stirring clarification more than 2 hours, the supernatant liquor of second order reaction is just refining bittern, and second order reaction mud pumps into mud disposal system.