CN1042842C - Method for prodn. of sodium chlorate by enclosed circulation of non-evaporating mother liquor - Google Patents

Abstract

A method for producing sodium chlorate by electrolyzing salt, comprising preparing sodium chlorate by electrolyzing a saturated salt solution and putting the electrolyzed solution into a sodium chloride thickener to increase the NaCl concentration to 120-165 g/l with industrial salt, adding Urea, caustic soda, soda ash, and barium chloride are removed from hypochlorite, magnesium, calcium, and sulfate ions, and then enter the freezing crystallization tank to fold out the crystals, separate, and dry to obtain the product. The mother liquor enters the salt-dissolving tank to make saturated salt water and electrolyzes again. This closed-loop process avoids the treatment of hexavalent chromium ions and pollutes the environment, saves energy, reduces costs, and improves product quality. The thickener in the equipment is novel in design, powerful in function and high in efficiency.

Description

The method of the production sodium chlorate that electrolyzes table salt

The present invention relates to a kind of method of the production sodium chlorate that electrolyzes table salt, particularly use subzero fractionation method production sodium chlorate.

Sodium chlorate is increasing as its consumption of SYNTHETIC OPTICAL WHITNER such as paper pulp, fabric, and Gross World Product reaches 1,430,000 tons/year.At present, the production technique of sodium chlorate is still based on the salt electrolysis method, and its flow process as shown in Figure 1.This technical process greatest drawback be solution repeatedly vacuum-evaporation concentrate, energy dissipation is big; Secondly concentrate back Cr ⁶⁺Concentration also increases, and its barium salt also needs Application and Development after the precipitation process, otherwise contaminate environment, content overproof in the sodium chlorate product simultaneously; Have again sodium chlorate liquid concentrate the back than great (850～900g/l), very easily with the sodium-chlor particle suspension in solution, then need clarify precipitation for what get rid of, evaporation once more caused waste after precipitation also need be dissolved.

The present invention its objective is on the basis with the salt electrolysis method, changes traditional method of evaporation and is separated into the subzero fractionation method, and a whole set of new separating technology is provided, thereby avoids defective such as the miscellaneous and energy dissipation of technology.

Electrolysis section of the present invention still adopts the outer circulation type electrolyzer, the electrolysis saturated common salt aqueous solution, and its flow process sees shown in the accompanying drawing 2, and electrolysis makes that density of sodium chlorate reaches about 550g/l in the electrolytic solution, and sodium-chlor reaches 100～110g/l, uses NaClO then ₃-NaCl-H ₂The mixed dissolution degree principle of O adopts industrial crude salt to improve sodium chloride concentration in the sodium-chlor enrichment device of special use, makes it reach 120～165g/l.And the utilization electrolysis is finished liquid self temperature (need not heat) and is added urea, caustic soda, soda ash and bariumchloride to handle impurity such as by product hypochlorite and magnesium, calcium, sulfate ion, after separating its throw out, clear liquid enters the crystallisation by cooling jar, folds NaClO under 80～160 rev/mins stirrings and-10～5 ℃ ₃Crystal, crystal carries out dry packing and becomes product after separating.Entering of mother liquor salt operation enters electrolytic system after dissolving makes sodium-chlor reach 240～270g/l with salt, electrolysis once more, so repeatedly.Special-purpose sodium-chlor enrichment device as shown in Figure 3, it act as: the one, add sodium-chlor and make its concentration reach 120～165g/l, the crystallization that prevents sodium-chlor is not on the other hand dissolved and is flowed in the crystallisation by cooling jar and make that sodium chloride content exceeds standard in the crystalline sodium chlorate.Its size two drums that are configured to be made by the titanium material are formed, and outer bucket diameter is 1.7～2.2 times of interior bucket diameter, and interior bucket is than the high 200mm of outer bucket, as outer bucket diameter 600mm, high 1200mm, on the outlet pipe of band micropore is arranged, discharging hole is arranged down; An interior bucket diameter is 350mm, high 1400mm, and 4 100 * 100mm perforates are arranged symmetrically at the bottom, and electrolytic solution and industrial crude salt enter on interior bucket, constantly dissolve the back from perforate effusion down, return up from the outlet pipe of band micropore to spill out.The crystallisation by cooling jar has the chuck and the agitator that can lead to chilled brine for to make with stainless steel, and requiring mixing speed is 80～160 rev/mins, and temperature is-10～5 ℃.Because the closed cycle of mother liquor, the dichromate of adding does not run off, and not enrichment reduces consuming and three wastes processing.

Method of the present invention relatively has its outstanding feature with the method for evaporation of usefulness:

(1) technology is simple and reasonable.1. utilize the sodium-chlor temperature variation and solubleness is constant, and sodium chlorate under certain sodium chloride concentration through freezing crystallizable separating out (NaCl does not separate out simultaneously), this is just avoided repeatedly evaporation concentration to waste energy and the time, simplifies technology.2. there is not the enrichment of dichromate in mother liquor closed cycle, without special disposal, and non-hexavalent chromium ionic soil environment.3. electrolytic solution reduces cost without refined salt with Industrial Salt enrichment sodium chloride concentration.

(2) equipment reduces, and the novel and efficient height of sodium-chlor enrichment device, the crystallisation by cooling jar set up.

(3) because energy expenditure greatly reduces with cold method replacement method of evaporation.Frozen portions of the present invention is partly compared with method of evaporation, and its energy consumption has descended 97%.

(4) quality product surpasses national standard.In eight indexs, there are five to be better than the product that method of evaporation is produced.Should be mentioned that especially the product appearance of producing with method of the present invention is pure white, crystal form is the quicksand shape, and exhausted nothing has caking.

(5) product cost descends more than 12% than method of evaporation.

Fig. 1 is the production sodium chlorate prior art separation process scheme figure that electrolyzes table salt.Fig. 2 is separation process scheme figure of the present invention.Fig. 3 is a sodium-chlor enrichment device synoptic diagram, and electrolytic solution and industrial crude salt are entered by interior bucket top, and the dissolving back enters outer bucket by interior bucket lower opening place gradually, is flowed out by outer bucket top band micropore outlet pipe.

Example

Drop into electrolysis and finish liquid 4.5m ³, NaClO wherein ₃Be 565g/l, NaCl102g/l; In sodium-chlor enrichment device, throw industrial crude salt 230kg (containing NaCl92.5%) then NaCl concentration rise to 148g/l, add urea 4kg, caustic soda 6.75kg, Na ₂CO ₃4.5kg BaCl26.75kg is to remove impurity such as hypochlorite and magnesium, calcium, sulfate ion.Electrolytic solution after the processing is made a gift to someone in the freezing and crystallizing jar, under-10～5 ℃, 80 rev/mins mixing speed, separate out crystallization and separate NaClO ₃820kg gets product 758kg after the drying.Mother liquor enters the molten system saturated brine of dissolved salt jar, wherein K ₂Cr ₂O ₇Content is 2.5g/l, is used for electrolysis once more.Product all reaches country-level standard.

Claims (3)

1, a kind of method for producing sodium chlorate by electrolytic table salt, comprise the sodium chlorate electrolytic solution that each contains 550g/l sodium chlorate and 100～110g/l sodium chloride electrolytic solution, it is characterized in that electrolysis completes liquid in chlorination Raw salt in the processing industry is increased in the sodium concentrator, and the NaCl concentration is 120-165g/l. Add urea, caustic soda, soda ash, and _BaCl to remove hypochlorite, magnesium, calcium, and sulfate ions. The solution enters the freezing crystallization tank. Stirring at 80-160 rpm and at -10-5°C, the crystals are folded out, separated and dried to obtain the product; the mother liquor enters the salt process, and the salt is dissolved to make NaCl reach 240-270g/l, and then enters the electrolysis system again electrolysis. 2. The method for producing sodium chlorate by electrolyzing table salt as claimed in claim 1, characterized in that the structure of the sodium chloride thickener is as follows: it consists of two drums, the diameter of which is 1.7 to 2.2 diameters of the diameter of the inner drum. times, the height of the outer barrel is 1200mm, there is an outlet pipe with micro-holes on the top of the barrel, and a drain port at the bottom; the inner barrel is 200mm higher than the outer barrel, and there are four holes of 100×100mm evenly and symmetrically in the lower part, and the electrolyte and industrial raw salt come from the upper end of the inner barrel It enters, dissolves continuously, escapes from the lower opening, and returns to the outlet pipe above the outer barrel to flow out. 3. The method for producing sodium chlorate by electrolyzing table salt as claimed in claim 1 or 2, characterized in that the sodium chloride thickener is made of titanium.