CN1017416B

CN1017416B - Purification method of sodium sulphate type bittern

Info

Publication number: CN1017416B
Application number: CN 87108324
Authority: CN
Inventors: 满元康
Original assignee: Central South University
Current assignee: Central South University
Priority date: 1987-12-30
Filing date: 1987-12-30
Publication date: 1992-07-15
Also published as: CN1033782A

Abstract

The present invention relates to a method for purifying sodium sulfate type ore brine. The method is characterized in that ore brine slurry containing Mg(OH)2 and CaCO3 achieves favorable performance of sedimentation and filtration by controlling the technical conditions of working procedures, such as neutralization, adjustment, carbonation, etc., and properly adding active crystal seeds and flocculating agents, the initial settling speed is from 5 to 13.86 centimeters per minute, and the filter factor is from 300 to 670*10<-7> centimeters per second. The method can effectively and reasonably purify brine, greatly reduce the energy consumption of salt manufacture, and enhance the productivity of equipment and the quality of products. In addition, the present invention has the advantages of simple production process and equipment, automatic control, continuous production, low investment, low cost, and good social benefit and economic benefit.

Description

Purification method of sodium sulphate type bittern

The present invention relates to the purifying method of contains sodium sulfate bittern.

With hydromining method recovery well ore deposit lake salt and produce with vacuum-evaporation in the technology of sodium-chlor,, former bittern directly enters preheater and evaporation equipment system, the Mg that former bittern is brought into if not purifying in advance ²⁺And Ca ²⁺The all cpds that forms can cause preheater and the long scar of fouling of evaporator, and heat transfer rate is reduced, and hear rate increases, and not only causes being forced to frequent cleaning of evaporator, and equipment capacity descends, and owing to Mg in the product ²⁺, Ca ²⁺The compound and the former bittern silt content height that form cause whiteness low, influence quality product.In order to overcome the existing problem of the direct salt manufacturing of former halogen, people constantly study the processing method that adopts salt manufacturing behind the calcium magnesium that purifies earlier in the former bittern.Chinese higher education press in 1956 publishes the ME ripple and appoints work " inorganic salt technology " to introduce Na ₂SO ₄-Ca(OH) ₂-CO ₂The technological principle of method purified brine and method.1980 the 3rd phases " well mine salt technology " have been reported the proper station-service soda ash-soda processes of Romanian Buddhist ear, the gloomy factory in base of a fruit ground and Germany Stade station-service lime-carbon dioxide process refined brine cover with lime-soda process, Italy in Britain English salt company limited.Although about purifying Ca in the salt solution ²⁺, Mg ²⁺Method more, but for containing Na ₂SO ₄Former bittern, lime-sodium sulfate-carbon dioxide process are more suitable methods, because under the suitable operation condition, needn't add Na in bittern ₂SO ₄, and with Ca(OH) ₂As the source of alkali, do not consume soda ash or caustic soda, be expected to obtain good social benefit and economic benefit.But this method exists the defect of former bittern mud sedimentation strainability difference; Because Mg(OH) ₂Solubility product in the aqueous solution is very little, and enough OH are arranged in former aqueous salt brine ^-When existing, generate Mg(OH) ₂Speed of response be exceedingly fast, the reaction product dispersity that obtains is very high, usually makes former bittern mud be in colloidal state, liquid-solid separation very the difficulty, thereby be difficult in industrial application.Russian patent 767026 and 735566 adopts and adds Ca(OH) ₂And Na ₂SO ₄Way purify salt solution, with the preparation intermediate, generate methods such as coarse grain crystal of calcium sulfate, so as to improving mud sedimentation strainability, but settling velocity only is 0.6 meter/hour, effect is not satisfactory.

The objective of the invention is at the existing shortcoming of lime-sodium sulfate-carbon dioxide process, work out and a kind ofly can improve Mg(OH in the bittern) ₂And CaCO ₃The method of mud sedimentation strainability is so that lime-sodium sulfate-carbon dioxide process becomes the bittern purifying method with industrial application value.

Feature of the present invention is by control neutralization (1), adjusts the appropriate technology condition of (2), a sedimentation (4), carbonating (5), secondary settlement main former bittern purifying operations such as (6) and add active seed and flocculation agent, makes Mg(OH) ₂And CaCO ₃Mud has good sedimentation strainability, contains Na thereby purify effectively, economically ₂SO ₄Former bittern.

The present invention is suitable for containing Na ₂SO ₄The scavenging process of the heavy magnesium deliming of the former bittern of natural well ore deposit lake salt, the former bittern that enters neutralization (1) groove requires NaCl concentration 270～300 grams per liters, Na ₂SO ₄Concentration 10～35 grams per liters, Ca ²⁺Concentration and Mg ²⁺Concentration is not limit.

The principle technical process that lime-sodium sulfate-carbon dioxide process purifies former bittern as shown in Figure 1.(Wingdale that with lumpiness is 80～180mm is 1050～1250 ℃ of calcinings down for the refining milk of lime that the former bittern and the CaO concentration of above-mentioned composition is 50～180 grams per liters, and after thoroughly decomposing, be added continuously in one group of digestion fractionated device systems with water, preparing the refining milk of lime that CaO concentration is 50～180 grams per liters more than 80 ℃) and do overflow (Mg(OH) behind a sedimentation (4) the process underflow classified (9) of crystal seed ₂Mud) and former bittern be added continuously to and have in churned mechanically neutralization (1) groove and purify (heavy magnesium) reaction.Add and contain Mg(OH) ₂Classification (9) overflow, be for the generation that suppresses new nucleus and promote Mg(OH) ₂Crystal growth, add-on is controlled with concentration of hydraulic mixture.The refining milk of lime amount that adds neutralization (1) groove is controlled by measuring mud PH value, and bittern mud temperature should be at 10～40 ℃ in neutralization (1) groove, and pH value is controlled in 10～11.2 scopes; Concentration of hydraulic mixture is controlled at 20～45 grams per liters.Former bittern purifies (heavy magnesium) 20～40 minutes in neutralization (1) groove, enter adjustment (2) groove then continuously, adds refining milk of lime again in former bittern mud, and the pH value of former bittern mud is transferred to greater than 12.1.Adjusted former bittern mud enter before a sedimentation (4) groove by mud weight add 100,000/to millionth unconverted monomer content less than 0.5% polyacrylamide (PAM) solution, and in waterpower mixing (a 3) groove, be pre-mixed evenly, to improve the settling velocity of magnesium mud.Through the overflow of a sedimentation (4) and the underflow after classified (9), deliver to carbonating (5) groove continuously by filtrate behind the filtration washing (10) and wash water again, feed the CO that concentration of volume percent is 30-38% simultaneously ₂(utilizing the kiln gas of calcined limestone) carries out carbonating (5) operation with deliming.Its operational condition is controlled temperature 20-60 ℃, mud PH value 9.2-9.5, and with secondary settlement (6) underflow that returns, the overflow mud after classified (7) (contains CaCO ₃The 50-100 grams per liter) as crystal seed, control carbonating (5) process CaCO ₃Content is the 10-30 grams per liter, and the activity duration is 20-40 minute.The control of mud PH value is by regulating CO ₂Gas flow is realized.Underflow after the classification (7) is all by filtration washing (8).The filtrate and the dense wash water of secondary settlement (6) overflow and filtration washing (8) are refined brine, send the salt manufacturing of salt manufacturing workshop.Refined brine generally contains NaCl250-308 grams per liter, Ca ²⁺∠ 3ppm, Mg ²⁺∠ 1ppm.

The present invention has the following advantages compared with the prior art:

1. the bittern mud of heavy magnesium process has good sedimentation strainability.Just settling velocity is 3-8.32 rice/time, and filter factor is 300-670 * 10 ^-7Cel, thus increased substantially sedimentation filter plant production capacity, make the technology of lime-sodium sulfate-carbon dioxide process calcium-magnesium removing, refined brine can be applied to industrial practice;

2. technical process and equipment are simple, and reduced investment can reduce the energy expenditure of salt manufacturing operation and the production capacity and the quality product of raising salt making equipment, and particularly heavy magnesium deliming process adopts automatically regulates, realization automatic control continuous production;

3. scavenging process produced calcium slag and magnesium slag all can fully utilize, and the leaching requirement open circuit is little, be easy to handle, and whole process flow toxicological harmless gas evolution, thereby do not pollute the environment;

4. as the CaCO in alkali source ₃Aboundresources, cheap;

5. the quality height of refined brine, the rate of recovery of scavenging process NaCl are more than 99%, and it is low to purify cost, and social benefit and overall economic efficiency are good.

Example:

With chemical constitution (grams per liter) is Mg ²⁺0.34, Ca ²⁺0.22, Na ⁺111.28, Cl ^-156.75, SO ²⁺ ₄25.49 10 liters in the former bittern of well mine salt of contains sodium sulfate and the refining milk of lime of CaO 162.5 grams per liters and as the Mg(OH of crystal seed) ₂Mud (containing Mg(OH) ₂95 grams per liters) add the heavy magnesium of neutralization (1) groove continuously.The neutralization that heavy magnesium is used (1) groove is the glass guide channel of 200 * 100 millimeters of φ; The electrical heating element of charged electric relay and mercury conductivity meter measuring and controlling temp is housed in the groove, and processing temperature fluctuates in 0.5 ℃.It is in 40 ℃ neutralization (1) groove that the former bittern of the well mine salt of above-mentioned chemical constitution is added to processing temperature with 6 liters/hour speed, and adds the Mg(OH as crystal seed) ₂Mud, controlling total concentration of hydraulic mixture is 40 grams per liters, the milk of lime addition is 10.4-10.6 control with the mud PH value in given neutralization (1) groove, heavy reactive magnesium 25 minutes.Mud continuous overflow in neutralization (1) groove is in adjustment (2) groove of band refrigerating unit, be 25 ℃ in the mud temperature and add milk of lime down continuously, PH is transferred to 12.1, press 100,000 of mud gross weight/interpolation PAM solution simultaneously, mud is added continuously in a sedimentation (4) groove then, after the sedimentation (4) 10 minutes, take out primary brine (overflow) 7 liters, remaining 3 liters of mud underflows send filtration washing (10).Filtration area is 630cm, and filtration time is 90 seconds, and gained filtrate is 2.6 liters.The supernatant liquor (overflow) of filtrate and sedimentation (4) groove and the filtrate of filtration washing (10) and dense wash water merge, and the feeding volumetric concentration is 30% CO in carbonating (5) groove that a band stirs ₂Gas, and add CaCO simultaneously ₃The mud crystal seed (contains CaCO ₃100 grams per liters), keep CaCO in the salt solution ₃Content be 30 grams per liters, when PH is 9.5, stop carbonating.Take out 50% supernatant liquor (overflow) after secondary settlement (6) leaves standstill 20 minutes, remaining mud washs (8) after filtration, and supernatant liquor (overflow) is merged into 9.72 liters with filtrate, adds 0.32 liter of dense wash water again, makes 10.04 liters of refined brines altogether.Through check, refined brine contains NaCl252.23 grams per liter, Na ₂SO ₄37.08 grams per liter, Ca ²⁺2.3PPm, Mg ²⁺0.89PPm.

Claims

1, a kind of purifying method of removing calcium, magnesium from contains sodium sulfate bittern is characterized in that:

(1) in having churned mechanically neutralization (1) groove, add former bittern and refining milk of lime continuously, simultaneously with behind a sedimentation (4) underflow classified (9), its effluent concentration is 95 grams per liter Mg (OH) ₂Return neutralization (1) groove and make crystal seed, the amount of adding is to keep bittern concentration of hydraulic mixture 20-45 grams per liter in neutralization (1) groove, and controlled temperature 10-40 ℃, activity duration 20-40 minute, the control mud PH value was 10-11.2;

(2) in the material that comes self-neutralization (1) groove, add above-mentioned refining milk of lime, to adjust the bittern mud PH value greater than 12.1;

(3) in above-mentioned bittern mud through regulating pH value, by its weight add 100,000/to millionth, unconverted monomer content less than 0.5% polyacrylamide (PAM) solution, after mixing (3), enter a sedimentation (4);

The filtrate of (4) sedimentations (4) overflow behind a sedimentation (4) underflow classified (9), filtration washing (10) enters in carbonating (5) groove, and the effluent concentration behind the secondary settlement underflow classified (7) is the CaCO of 50-100 grams per liter ₃Return carbonating (5) groove and make crystal seed, control carbonating (5) groove CaCO ₃Content is the 10-30 grams per liter, and under temperature 20-60 ℃, the feeding concentration expressed in percentage by volume is 30-38%CO ₂To control its PH9.2-9.5, the activity duration is 20-40 minute;

(5) then secondary settlement (6) overflow and secondary settlement (6) underflow classified (7), filtration washing (8) gained filtrate are mixed and the bittern of the contains sodium sulfate that is purified.

2, purifying method according to claim 1 is characterized in that Wingdale 1050-1250 ℃ of calcining down, and after thoroughly decomposing, prepares the refining milk of lime that CaO concentration is the 50-180 grams per liter in water digestion more than 80 ℃.