CN1020272C - Preparation method of magnesium sulphate and sodium chloride from high temp. salt - Google Patents

Abstract

The present invention relates to a method for preparing magnesium sulphate and sodium chloride by waste slag with high-temperature salt in the process of bittern chemical chloratum kalium production of similar seawater systems. The high-temperature salt is prepared into high-temperature salt slurry, the salt slurry is separated by an overflow separator, and the separated magnesium sulfate is converted, washed and separated to produce magnesium sulfate hydrates of dihydrate to heptahydrate; or the high-temperature salt slurry is converted, and then is separated by the overflow separator, and the separated product is refined into magnesium sulfate and sodium chloride. The magnesium sulfate yield reaches more than 89%, and the sodium chloride yield reaches more than 92%. The present invention has the advantages of no need of adding any additive, no three waste pollution, reliable technique, low investment and obvious economic benefit, and is suitable for the comprehensive utilization of high-temperature of brine chemical plants.

Description

Preparation method of magnesium sulphate and sodium chloride from high temp. salt

The invention belongs to the comprehensive utilization of similar seawer system bittern aquation worker waste residue high temp. salt.

The waste that the bittern method of evaporation is produced behind the Repone K is in the high temp. salt, and sulfur acid magnesium is about 30%, sodium-chlor is about 30%, and contains small amount of impurities such as Repone K, magnesium chloride and bromine, ten tons of high temp. salts of the about by-product of one ton of Repone K of every production.Both at home and abroad high temp. salt is not made full use of as yet at present, domestic most of producer all discard need not, promptly water melts to enter to refute and continues to evaporate brine or enter the sea in the salt ditch, as spends to evaporate brine the sal epsom amount is increased, produce vicious cycle, not only polluted product but also wasted resource; Domestic some producer still adopts different methods that high temp. salt is reclaimed, as " natural freezing method ", freeze system sal glauberi with high temperature salinization halogen winter, be reprocessed into anhydrous sodium sulphate (claiming anhydrous nitre again), this method investment is many, the cost height, energy consumption is big, its sal epsom rate of recovery has only about 40%, and recent anhydrous nitre is unsalable, and some producer has to stop production; The principle that " hot melt soaks method " Nan Bao chemical plant utilizes common-ion effcet and increases the total ionic strength adjustment buffer degree is the thin up high temp. salt at first, heating then, leach with magnesium chloride solution, remove the suspension naturally frozen or freeze the system magnesium sulfate heptahydrate again behind the sodium-chlor with the mechanical refrigeration method, this method equipment is many, and energy consumption is big, and the sal epsom rate of recovery has only about 45%, the sodium-chlor rate of recovery has only about 30%, not fine as yet applying in actual production process; " succusion ", saltern, Hangu utilizes the reason that sodium-chlor is different with the sal epsom particle, proportion is different thereby settling velocity is different, adopt vibration separation of produced magnesium sulfate heptahydrate, but this method can not effectively be separated sal epsom with sodium-chlor, the rate of recovery of magnesium has only 30～40%, and sodium-chlor still can not be recycled.

The present invention there are differences in view of sal epsom and sodium-chlor crystalline characteristics, be that proportion and granularity have than big-difference, one water and magnesium sulfate heptahydrate are the magnesia magma shape, magnesium sulfate heptahydrate proportion is 1.68, sodium-chlor proportion is 2.165, granularity is bigger, analyze discovery by screen analysis, account for 87.20% at the above sodium-chlor of 200 orders, the following magnesium salts of 200 orders accounts for 95.88%, from then on draws significantly to have the separableness conclusion, and the hydraulic classification that the present invention utilizes mining industry department to adopt is that the overflow size separation principle is utilized static vertical-overflow device, the overflow separation method of control certain flow rate is applied to separating of magnesium salts and sodium salt in the high temp. salt, has obtained satisfied result.

The object of the present invention is to provide a kind of static vertical-overflow device that utilizes, the method for magnesium salts in the overflow separating high-temp salt of control certain flow rate.

The present invention is achieved in that the waste residue high temp. salt that has now in the producing potassium chloride by halogen conversion method process by the method for high temp. salt system sal epsom, its sal epsom/sodium-chlor ratio is 0.4～2.5, with the dense halogen in crude magnesium clear liquor or the system potassium process or mix halogen to be mixed with solid-to-liquid ratio be 1: 0.5～1: 5 high temp. salt slurry, separate to such an extent that crude magnesium breast and crude salt are starched by flooding separator, the crude magnesium breast is through concentrating clarifying, separate, add water transform washing separate the sal epsom product, the crude salt slurry is through separating, add water washing separate the sodium-chlor product, this is to separate earlier afterwards to transform the purified method, and accompanying drawing 1 is seen in technical process.

The present invention is by the method for high temp. salt system sal epsom, with bittern chemical factory waste residue high temp. salt is raw material, getting a certain amount of sal epsom/sodium-chlor ratio is 0.4～2.5 high temp. salt, add the dense halogen in quantitative crude magnesium clear liquor or the system potassium process or mix halogen, being mixed with solid-to-liquid ratio is 1: 0.5～1: 5 high temp. salt slurry, the before flooding separator top that is full of the crude magnesium clear liquor adds, add with the bottom of crude magnesium clear liquor simultaneously from flooding separator, the control flow velocity is 1.2～7.1M/h, the crude magnesium breast is flowed out from the last overflow port of flooding separator, contain MgSO ₄H ₂The crude magnesium breast of O is through concentrating, clarification separates to such an extent that crude magnesium is starched and the crude magnesium clear liquor, crude magnesium slurry through separate crude magnesium and crude magnesium separatory, crude magnesium transforms the washing separation through adding water again, its amount of water is 15～90% of a crude magnesium amount, stir to transform washing through 40～60 minutes, correspondingly controlled temperature is 10～100 ℃, and the magnesium sulfate hydrate that can obtain containing crystal water and be two water to seven water is the finished product; The crude salt slurry of discharging from flooding separator bottom through separate crude salt and crude salt separatory, crude salt is again through adding sodium-chlor product and the refined salt separatory that water washing separates qualifiedly, do the one way test with above-mentioned flow process, the yield of sal epsom can reach 71.47%, the sodium-chlor yield is 78.18%, its purity is more than 98%, the crude magnesium clear liquor of output from said process, the crude magnesium separatory, smart magnesium separatory, refined salt separatory, the merging of refined salt separatory is commonly referred to as the halogen of growing nonparasitically upon another plant together, can return the Repone K workshop and do the raw material use, produce magnesium salts again through recirculation, two kinds of qualified product of sodium salt, the new halogen of growing nonparasitically upon another plant returns again, the circulation that goes round and begins again is like this gone down, and consequently the sal epsom yield can reach 89.97% in this system, and the sodium-chlor yield can reach more than 92.88%.

With reference to accompanying drawing 2, the present invention is a flooding separator by its key equipment of method of high temp. salt system sal epsom, it is by main body (1), last filling tube (2), overflow groove (3), overflow port (4), following opening for feed (5), distribution piping (6), crude salt slurry store holder (7) and end discharge gate (8) are formed, the agent structure form is straight tubular, also can be made into top fuller shape, also can be made into diameter greater than height, band stirs frame, the bottom is the form of top fuller shape, no matter adopt which kind of form, all act as purpose to play overflow size separation, in order to make the crude magnesium clear liquor evenly enter separator, described distribution piping (1) can be made into the outer forms of distribution of dividing four～six mouths to be communicated with store holder around crude salt slurry store holder, also can make annular in store holder inside and divide the interior forms of distribution of four～six spouts, described high temp. salt slurry adds from last filling tube (2), the crude magnesium clear liquor goes out down, and opening for feed (5) enters, divide four～six mouths to enter the bottom of crude salt slurry store holder (7) through distribution piping (6), rise with 1.2～7.1M/h speed, the control flow velocity makes the crude magnesium breast flow out and do not make sedimentation from last overflow port (4) just, makes the sodium-chlor sedimentation and unlikely overflow is gone out.

The present invention is by the method for high temp. salt system sal epsom, and control transformation time and invert point purpose are the magnesium sulfate hydrates that obtains containing the different crystal water of two water to seven water, and existing document announcement invert point and sal epsom crystal water quantity corresponding relation are as follows:

Invert point sal epsom product

80～100℃ MgSO ₄.2H ₂O

70～80℃ MgSO ₂.3H ₂O

48～68℃ MgSO ₄.6H ₂O

10～40℃ MgSO ₄.7H ₂O

The present invention is by the method for high temp. salt system sal epsom, produce the halogen of growing nonparasitically upon another plant in the production process and comprise that high temp. salt is solid phase and carries Repone K in the liquid phase, magnesium chloride, bromine secretly in recycling, make the rate of recovery on former basis, improve more than 15%, calculate to produce 40000 tons of comprehensive products of Repone K per year in the whole nation, by processing method of the present invention, can go out 6000 tons of comprehensive products of Repone K by fecund.

The method of high temp. salt system sal epsom of the present invention can make high temp. salt thoroughly be utilized, and technology is simple, and energy consumption is lower, and reduced investment, benefit are very remarkable, is applicable to the comprehensive utilization of similar seawer system salt chemical engineering.

Description of drawings:

Accompanying drawing 1 is the schematic flow sheet by the method for high temp. salt system sal epsom.

Accompanying drawing 2 is the flooding separator structural representation.

Embodiment sees Table 1

Table 1:

Project data numbering embodiment 1 embodiment 2 embodiment 3

High temp. salt consumption (g) 1733.1 1,352 813

High temp. salt slurry solid-to-liquid ratio 1: 0.5 1: 11: 2

Partial flow rate M/h 1.2 4.58 6.5 overflows

Crude magnesium washing conversion condition: amount of water (g) 317 317 317

Churning time 1h 1h 1h

Washing invert point ℃ 27 27 27

Washing separating method centrifugation centrifugation centrifugation

Get smart magnesium amount (g) 563 809 712

Smart magnesium composition (g) Nacl-0.59-

Mgso ₄48.78 49.80 47.93

Mgcl ₂0.54 0.01 0.94

Kcl - - -

Mgso ₄·7H ₂O（%） 99.73 100.90 93.09

Get refined salt amount 865 456 150

Refined salt composition (%) wet basis Nacl 96.63 96.71 95.94

Mgso ₄0.65 0.77 0.75

Mgcl ₂0.19 0.20 0.22

Kcl - - -

Butt sodium-chlor (%) 99.14 99.01 98.99

+ 0.5% water post chlorization sodium (%) 98.63 98.50 98.48

Annotate: the crude salt purification condition omits.

Claims (1)

1, a kind of method by high temp. salt system sal epsom, it is characterized in that with sal epsom/sodium-chlor ratio being: the high temp. salt of 0.4-2.5 is mixed with the high temp. salt slurry with crude magnesium clear liquor or bittern, separate to such an extent that crude magnesium breast and crude salt are starched by flooding separator, the crude magnesium breast through concentrating clarifying, separate, add that water transforms, washing separates to such an extent that contain the sal epsom product of two water to seven water, the main technique condition is:

A, high temp. salt slurry solid-to-liquid ratio: 1: 0.5～1: 5;

Flow rate of liquid: 1.2～7.1m/h in b, the flooding separator;

Amount of water was 15～90% of a crude magnesium amount when c, crude magnesium breast added the water conversion;

D, transformation time: 40～60 minutes;

E, invert point: 10～100 ℃.

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