CN101050006A

CN101050006A - Technique for refining salt water

Info

Publication number: CN101050006A
Application number: CN 200710040622
Authority: CN
Inventors: 赵志安
Original assignee: XIEN CHEMICAL EQUIPMENT CO Ltd SHANGHAI
Current assignee: XIEN CHEMICAL EQUIPMENT CO Ltd SHANGHAI
Priority date: 2007-05-14
Filing date: 2007-05-14
Publication date: 2007-10-10

Abstract

This invention relates to a process for refining brine. The process comprises: dissolving raw salt in a brine barrel, adding NaOH and Na2CO3 or adding Na2CO3, NaOH and BaCl2 under stirring at 0.5-3 m/s, adding flocculant, pumping uniformly reacted brine into a filter, performing solid-liquid separation, vacuumizing every 4-24 h, backwashing, dehydrating discharged salt mud, treating dry mud and returning the brine to the filter. The residual amounts of NaOH and Na2CO3 after reaction are kept 0.1-0.3 g/L and 0.4-0.6 g/L, respectively. The process has such advantages as small floor area and high removal rate of suspended substances (99%), high stability, high impact resistance, and high refined brine quality.

Description

Brine rectification process

Affiliated technical field

The present invention relates to a kind of brine treatment technology, and relate more specifically to a kind of brine rectification process.

Background technology

Crude salt is the main raw material of chlorine industry, and crude salt is made salt solution, because crude salt is impure, makes and often contain suspended substance and metal ion in the salt solution, as: Ca ²⁺, Mg ²⁺, Fe ³⁺, SiO ₂, SO ₄ ²⁺Deng material, these materials enter diaphragm electrolysis operation or electrolysis with ion-exchange film operation, then can damage electrolytic film, shorten the work-ing life of electrolytic film, therefore must these ions and suspended solids be removed by refining.

Filtering technique in the brine rectification process, brine filter in diaphragm electrolysis system alkaline process is produced, the general natural subsidence that adopts adds the sand-bed filter method, it as shown in Figure 1, with the crude salt dissolving, add and enter settling tank by the gravity settling particle after chemical agent reacts earlier, supernatant liquor also has a small amount of trickle suspended substance, further purify through sand filtration again and make refined brine one time, deliver to barrier film or ionic membrane operation.Because operation is relatively tediously long, therefore when occur salt solution fluctuate, when quality is poor slightly, the shock-resistant ability of equipment will make the salt solution concentration of suspension exceed standard, and influences the work-ing life and the quality product of barrier film or ionic membrane.There is the shortcoming that floor space is big, filtering accuracy is not high enough in this technology.

Along with the widespread use of ionic membrane, membrane separation process occurred and substituted original technology.Its technological process block-diagram is as shown in Figure 2: the crude salt dissolving, add and enter air-floating apparatus after the chemical agent hybrid reaction and remove Mg (OH) ₂Suspended substance is squeezed into the further refining CaCO of removal of membrane separation plant with pump then ₃With other suspended substance.Though the water outlet precision of this technology is higher than the sand-bed filter method, can satisfy the production demand of ionic membrane method, compare with sand-bed filter method technology, exist: operating process is loaded down with trivial details; Defectives such as matting, working cost height are invested greatly, needed to film filter, and film is handled the very high film that is easy to of the requirement of former water is stopped up.

Summary of the invention

The object of the present invention is to provide a kind of solid-liquid separation effect remarkable, suspended substance (SS) clearance height, it is few to go out water suspension, and the quality of a refined brine is higher than present traditional technology and the new brine rectification process of membrane separation process.

The present invention is realized by following design:

Crude salt is dissolved by light salt brine in salt dissolving tank, flows into then to stop in the hybrid reaction groove 0.5～1.0 hour; In the way of flowing through, add NaOH and Na ₂CO ₃, or add Na ₂CO ₃, NaOH and BaCl ₂, and the limit is reinforced, the limit is with the speed of 0.5～3 meter per second continuously stirring forward incessantly; Add flocculation agent in the salt solution after hybrid reaction again; Salt solution is squeezed into liquid filter and carry out solid-liquid separation with pump.

Described dosage is to guarantee that reaction residual content NaOH is 0.1～0.3g/L, NaCO ₃Be 0.4～0.6g/L.

The described flocculation agent that adds is the poly-propionyl acid sodium of 1～3mg/L and the iron trichloride of 5～30mg/L.

Described liquid filter is liquid filter A or liquid filter B.

Opened the gas exhausting valve of liquid filter B every 4～24 hours, the air that evacuation of air is indoor, strainer carries out back flushing simultaneously.

The salt slurry of liquid filter bottom discharging is squeezed into plate-and-frame filter press with pump and is dewatered, and dried mud outward transport is handled, and salt solution is then got back to liquid filter.

Effect of the present invention is clearly,

1. the present invention compares with membrane separation process with traditional technology, has simplified technical process, and floor space is little, and facility investment is few;

2. continuously-running of the present invention, recoil, spoil disposal need not termination of pumping.It is easy to operate to recoil, and operation energy consumption is low, and working cost is few.And after membrane separation process operation for some time in order to keep higher filtration capacity, need with chemical agent regeneration, and annually also have high film replacement charge.

3. suspended substance removal rate of the present invention is high and stable, and strong shock resistance, effluent quality can not change because of the fluctuation of influent quality, have guaranteed the quality of a refined brine.And membrane separation process anti impulsion load ability in order to prevent into water to the pollution of film device, must guarantee the salt solution effects of pretreatment, otherwise, not only can polluted membrane equipment, cause operation undesired, and influenced the quality of a refined brine.

Following table 1 is with 90m ³/ h treatment capacity is an example, and the performance of each processing method compares:

The performance comparison sheet of three kinds of technologies of table 1

Project	The sand-bed filter method	Membrane separation process	Technology of the present invention
Project	The sand-bed filter method	Membrane separation process	Technology of the present invention	Investment	3,200,000 yuan	3,200,000 yuan	2,000,000 yuan
Working cost	60,000 yuan	350,000 yuan	50,000 yuan	Investment	3,200,000 yuan	3,200,000 yuan	2,000,000 yuan
Working cost	60,000 yuan	350,000 yuan	50,000 yuan	Processing accuracy	2～5mg/L	≤1mg/L	≤1mg/L
Manipulation strength	Simply	Complicated	Simply	Processing accuracy	2～5mg/L	≤1mg/L	≤1mg/L
Manipulation strength	Simply	Complicated	Simply	It deny matting	Do not need	Need	Do not need

In a word, brine rectification process of the present invention compared with prior art has to take up an area of and lacks; Can make full use of the existing facility investment to transformation project economizes most; Operating performance is good, refined brine quality height; Simple to operation, effect such as working cost is low can be chlor-alkali plant salt refining and has opened up a new approach.

Description of drawings

Fig. 1 is the sand-bed filter method process flow sheet of salt solution natural subsidence.

Fig. 2 is a brine film partition method process flow sheet.

Fig. 3 is a brine rectification process schema of the present invention.

Embodiment

Below in conjunction with accompanying drawing embodiments of the invention are described, thereby made CONSTRUCTED SPECIFICATION of the present invention, characteristics, purpose and advantage clearer and more definite, but be not to be used for limiting scope of the present invention.

Embodiment one:

As shown in Figure 3, a kind of brine rectification process, its: earlier crude salt is dissolved by light salt brine in salt dissolving tank, in the way of flowing through, add NaOH and Na ₂CO ₃, flow into then and stopped in the hybrid reaction groove 0.5～1.0 hour, guarantee that Ca, Mg fully react to generate CaCO ₃And Mg (OH) ₂And the limit is reinforced, the limit is with the speed of 0.5～3 meter per second continuously stirring forward incessantly, and purpose is to allow it finish reaction fully.Institute's dosage is to guarantee that reaction residual content NaOH is 0.1～0.3g/L, NaCO ₃Be 0.4～0.6g/L.Water outlet after the hybrid reaction drops into poly-propionyl sodium of flocculation agent and iron trichloride again, can the flocculation of the suspending sundries in the salt solution is agglomerating, and will squeeze into liquid filter with pump through the salt solution after flocculation agent and water mix then and carry out solid-liquid separation.Through the filtering water of CN liquid filter, one-level is filtered suspended substance less than 5mg/L.Cascade filtration less than 1mg/L, directly enter the secondary refining operation again.

What the present invention adopted is the liquid filter that the contriver applies for Chinese patent separately.Can singly use liquid filter A, i.e. the CN I type filter that provides of contriver; Perhaps single liquid filter B that uses, i.e. the CN II type filter that provides of contriver; Present embodiment that also can be as shown in Figure 3, with body strainer A at night (CN I type filter) and liquid filter B (CN II type filter) string with carrying out cascade filtration, its best results.Its solid-liquid separation effect is remarkable, and suspended substance (SS) clearance height is not less than 99%, goes out water suspension less than 1mg/L, and can remove most of Ca ²⁺, Mg ²⁺Deng metal ion, guarantee to make liquid effluent limpid, the quality of a refined brine can replace present traditional technology and membrane separation process fully.

Opened the gas exhausting valve of liquid filter B every 4～24 hours, the air that evacuation of air is indoor carries out back flushing to strainer simultaneously, this moment needn't spoil disposal to save clear water.

The liquid filter bottom is provided with the device of discharging salt slurry, and the spoil disposal of one-level filter for molten is spaced apart 1～3 hour, and secondary filter is 12～24 hours, and each sludge volume is 1～2M ³The salt slurry of liquid filter bottom discharging is squeezed into plate-and-frame filter press with pump and is dewatered, and dried mud outward transport is handled, and salt solution is then got back to liquid filter.

Inner Mongol measured data: feed liquor SS is 2.5～3.5g/L, adopts CN type filter one-level to filter, result such as the table 2 surveyed once every 4 hours.

Table 2 Inner Mongol measured data

Sequence number	1	2	3	4	5	6
Sequence number	1	2	3	4	5	6	SS(mg/L)	1.76	1.16	1.0	0.9	0.7	0.5

And described liquid filter material of main part is Vinylite FRP, and acid-fast alkali-proof is anti-oxidant, and is corrosion-resistant, maintenance load is few, work reliability is high, and do not need every year and carry out anticorrosion maintenance more than 10 years integrally-built normal work-ing life.Liquid filter low pressure operation continuously, the regular discharge concentrated solution, operational administrative is very convenient.

Liquid filter B has wind box, and the air backwash pipe and the gas exhausting valve that allow wind box communicate with atmosphere, opened the gas exhausting valve of liquid filter B every 4～24 hours, air in the wind box passes through air backwash tube drainage to atmosphere, clear liquid in the liquid filter forms one strong wallop when descending rapidly, play the back flushing effect, described self backwashing technology filter stoppage and fouling can not occur, to guarantee secular filter effect.And when recoil needn't termination of pumping, the strainer continuously-running; Recoil does not need to appoint watches medium, easy to operate; The recoil water loss is little, need not matting.

The salt slurry of liquid filter bottom discharging is squeezed into plate-and-frame filter press with pump and is dewatered, and handles in the mud outward transport, and salt solution is then got back to liquid filter.Discharging can termination of pumping during salt slurry, discharges the about 1～2m of salt slurry at every turn ³, specifically looking into, the water concentration of suspension decides.

Embodiment two:

Production technique adds Na with embodiment one to the hybrid reaction groove ₂CO ₃, NaOH and BaCl ₂, generate CaCO ₃, Mg (OH) ₂And BaSO ₄, filter through CN type liquid filter one-level, as Sichuan measured data result such as table 3.

Table 3 Sichuan measured data

Embodiment three:

The same Fig. 3 of production technique adds NaCO in pipeline ₃, NaOH, BaCL ₂, generate CaCo ₃, Mg (OH) ₂And BaSO ₄Throw out is through CN type liquid filter second-stage treatment, as instance data result of Jiangsu factory such as table 4

Table 4 Jiangsu factory measured data

Sichuan Province's salt chemical product quality salt is superintended and directed the inspection center to adopting the detected result such as the table 5 of explained hereafter product of the present invention.

Table 5 product detected result

Claims

1. brine rectification process, it is characterized in that: crude salt is dissolved by light salt brine in salt dissolving tank, flows into then to stop in the hybrid reaction groove 0.5～1.0 hour; In the way of flowing through, add NaOH and Na ₂CO ₃, or add Na ₂CO ₃, NaOH and BaCl ₂, and the limit is reinforced, the limit is with the speed of 0.5～3 meter per second continuously stirring forward incessantly; The flocculation agent that adds in the salt solution after hybrid reaction again; Salt solution is squeezed into liquid filter and carry out solid-liquid separation with pump.

2. by the described brine rectification process of claim 1, it is characterized in that: described dosage, to guarantee that reaction residual content NaOH is 0.1～0.3g/L, NaCO ₃Be 0.4～0.6g/L.

3. by the described brine rectification process of claim 1, it is characterized in that: the described flocculation agent that adds is the poly-propionyl acid sodium of 1～3mg/L and the iron trichloride of 5～30mg/L.

4. by the described brine rectification process of claim 1, it is characterized in that: described liquid filter is liquid filter A or liquid filter B.

5. by the described brine rectification process of claim 4, it is characterized in that: opened the gas exhausting valve of liquid filter B every 4～24 hours, the air that evacuation of air is indoor, strainer carries out back flushing simultaneously.

6. by the described brine rectification process of claim 4, it is characterized in that: the salt slurry of liquid filter bottom discharging is squeezed into plate-and-frame filter press with pump and is dewatered, and dried mud outward transport is handled, and salt solution is then got back to liquid filter.