Production of table salt. Table salt

Keywords

HALITE WASTE/ HALITE WASTE / TECHNICAL SODIUM CHLORIDE/TECHNICAL SODIUM CHLORIDE/ FOOD GRADE SALT / / MATERIAL BALANCE/ MATERIAL BALANCE / TECHNOLOGICAL DIAGRAM/ TECHNOLOGICAL SCHEME

Annotation scientific article on industrial biotechnologies, author of the scientific work - Samady Murodjon Abdusalimzoda, Mirzakulov Holtura Chorievich, Rakhmatov Khudoyor Boboniyozovich

The results of research on processing are presented halite waste on . The optimal technological parameters for producing saturated solutions of sodium chloride from technical salt obtained from halite waste potash production. To do this it is necessary to dissolve technical sodium chloride in water at T:L = 1:(2.5-3), separate water-insoluble residues and organic matter by filtration. To isolate potassium chloride, saturated solutions were evaporated. Vapor? except for a saturated solution? were also exposed to sodium chloride solutions? pre-cleaned from sulfates, magnesium and calcium. Sulfates were precipitated with barium chloride at a molar ratio of SO42-:Ba2+=1:1, magnesium with calcium hydroxide at pH 10-12, and calcium with sodium carbonate at a ratio of CaO:CO2=1:1.05. When evaporating 50% of the water from the initial mass of the saturated solution, 81.55% of the salt from the initial amount in the solution is precipitated, and at the same time the sodium chloride content, in terms of dry salt, is 99.30%, and with preliminary purification 99.68 %. There are practically no organic substances. The fundamental technological scheme, scheme material flows And material balance processing halite waste potash production, obtained from sylvinites of the Tyubegatan deposit, at food grade table salt, as well as technological standards.

Text of scientific work on the topic “Technology of table salt of food purity from halite waste from potash production”

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TECHNICAL SCIENCES

TECHNOLOGY OF FOOD PURITY SALTA FROM HALITE WASTE OF POTASH PRODUCTION

Samady Murodjon Abdusalimzoda

assistant of the Tashkent Institute of Chemical Technology 100011, Republic of Uzbekistan, Tashkent, st. Navoi, 32

Email: [email protected]

Mirzakulov Holtura Chorievich

Professor of the Tashkent Institute of Chemical Technology 100011, Republic of Uzbekistan, Tashkent, st. Navoi, 32

Rakhmatov Khudoyor Boboniyozovich

Associate Professor of Karshi Engineering and Economic Institute 180100, Republic of Uzbekistan, Karshi, st. Mustakillik, 225

TECHNOLOGY OF TABLE SALT OF FOOD CLEANLINESS FROM HALITE WASTE OF POTASIUM MANUFACTURE

Murodjon Samadiy

Assistant of Tashkent institute of chemical technology, 100011, Republic of Uzbekistan, Tashkent, Navoi st., 32

Kholtura Mirzakulov

Professor of Tashkent institute of chemical technology, 100011, Republic of Uzbekistan, Tashkent, Navoi st., 32

Khudoyor Rakhmatov

Associate professor of Karshi engineering economical institute, 180100, Republic of Uzbekistan, Karshi, Mustakillik st., 225

Samadiy M.A., Mirzakulov Kh.Ch., Rakhmatov Kh.B. Technology of table salt of food purity from halite waste from potassium production // Universum: Engineering Sciences: electron. scientific magazine 2016. No. 3-4 (25). URL: http://7universum.com/ru/tech/archive/item/3083

ANNOTATION

The results of studies on the processing of halite waste into table salt of food purity are presented. The optimal technological parameters for obtaining saturated solutions of sodium chloride from technical salt obtained from halite waste from potash production have been identified. To do this, it is necessary to dissolve technical sodium chloride in water at T:L = 1:(2.5-3), to separate water-insoluble residues and organic matter by filtration.

To isolate potassium chloride, saturated solutions were evaporated. Vapor? except for a saturated solution? were also exposed to sodium chloride solutions? pre-cleaned from sulfates, magnesium and calcium.

Sulfates were precipitated with barium chloride at the molar ratio SO42-:Ba2+=1:1, magnesium with calcium hydroxide at pH 10-12 and calcium-sodium carbonate at the ratio Ca0:CO2=1:1.05.

When evaporating 50% of the water from the initial mass of the saturated solution, 81.55% of the salt from the initial amount in the solution is precipitated, and at the same time the sodium chloride content, in terms of dry salt, is 99.30%, and with preliminary purification - 99. 68%. There are practically no organic substances.

A basic technological diagram, a diagram of material flows and a material balance for processing halite waste from potash production obtained from sylvinites of the Tyubegatan deposit into table salt of food purity, as well as technological standards are presented.

to dissolve technical sodium chloride in water at S:L=1: (2.5-3) to separate the insoluble rests in water and organics waste materials by a filtration.

For extraction sated solutions of potassium chloride subject to evaporation. Except the sated solution is subject to evaporation also solutions of sodium chloride preliminary cleared from sulphates, magnesium and calcium.

Sulphates besieged with barium chloride at the molar ratio SO42-:Ba2 + = 1:1, magnesium - with calcium hydroxide at pH 10-12 and calcium - with sodium carbonate at the ratio Ca0:C02 = 1:1.05.

At the evaporation 50% of water from initial weight of the sated solution to deposit are allocated 81.55% of salt from initial quantity in a solution and thus the contents of sodium chloride, in recalculation for dry salt, contents 99.30%, and at preliminary clearing - 99.68%. Organic substances are practically absent.

The basic technological scheme, the scheme of material streams and material balance of processing halite waste of potassium manufacture received from sylvinites of the Tyubagatan deposit, to table salt of food cleanliness, and also norm of a technological mode are considered.

Key words: halite waste, technical sodium chloride, table salt of food purity, material balance, technological scheme.

Keywords: halite waste, technical sodium chloride, table salt of food cleanliness, material balance, technological scheme.

The potash industry is a new industry for the republic. In 2010, the first stage of the Dekhkanabad Potash Fertilizer Plant Unitary Enterprise was put into operation with a capacity of 200 thousand tons of potassium chloride per year. In 2014, the implementation of the expansion project of the Dekhkanabad Potash Fertilizer Plant Unitary Enterprise was completed, bringing the enterprise’s production capacity to 600 thousand tons of potassium fertilizers per year, and thus one of the main tasks was solved - full provision agriculture republics

potash fertilizers. As the second stage of the plant reached its design capacity, export supplies also increased.

The organization of potash production has also created new environmental problems. If one of them is halite waste, then the second is low-grade sylvinite ore. The importance of this problem is also evidenced by the fact that the issues of involving low-grade sylvinites in the process of production of flotation potassium chloride or their disposal by processing into other types of products are also indicated by the decision of the meeting of the Cabinet of Ministers of the Republic of Uzbekistan dedicated to this problem. When producing one ton of potassium chloride, up to four tons of halite tailings are formed, containing 85-90% sodium chloride. To obtain 600 thousand tons of potassium chloride, it is necessary to extract more than 2.2 million tons of rich sylvinite ore. At the same time, up to 1.5 million tons of halite waste are generated annually. With an increase in the amount of sylvinite ore mined by the mine method, the amount of low-grade sylvinites raised to the surface will also increase, the share of which reaches up to 50%.

Halite waste is currently partially processed to produce technical sodium chloride at the first stage of the Dekhkanabad Potash Fertilizer Plant Unitary Enterprise using a flotation machine, and with the help of low-grade sylvinite ores, the mine carries out the mixing and averaging of ore rich in potassium chloride. These measures do not significantly affect the reduction in the amount of generated halite waste and low-grade sylvinite ores, which are stored, occupying huge areas and polluting the environment, underground and above-ground water resources.

One of the most acceptable ways to dispose of halite waste for the Dekhkanabad Potash Fertilizer Plant Unitary Enterprise is to process it into technical sodium chloride for the chemical production of the republic and then into food grade sodium chloride. Many industries use the highest grades of food for technical purposes.

table salt. Thus, “Extra” grade salt is used in non-ferrous metallurgy in the production of magnesium and bimetals, in chemical industry-in the production of dyes and detergents, in industry building materials- when receiving glaze on products made of ceramics, earthenware, porcelain.

Therefore, the goal of the research was to develop a technology for processing technical sodium chloride obtained from halite waste into table salt of food purity.

For the research, we used technical sodium chloride, obtained industrially from halite waste and containing 89.28% sodium chloride, 0.75% potassium chloride, 0.74% calcium chloride, 0.08% magnesium chloride, 2.30% n. O. and 6.85% moisture.

Analysis of initial, intermediate and final products and solutions was carried out using known methods chemical analysis.

To obtain sodium chloride of food purity, technical salt from halite waste was dissolved in water at T:L = 1: (2.5-3.0), water-insoluble residues and organics were separated by filtering, a clarified, saturated solution of technical sodium chloride containing 26.69% 0.22% 0.28% Caa2, 0.025% MgSO4, and pre-purified

from sulfates with barium chloride at the molar ratio SO4-2:Ba+2=1:1, from magnesium ions with calcium hydroxide at pH=10-12 and calcium ions with sodium carbonate at the molar ratio Ca0:CO2=1:1.05 the solution was evaporated .

The solutions were evaporated at a temperature of 80-100 °C in a glass reactor, under a vacuum of 300 mm. rt. Art.

When moisture evaporates in an amount of 50% of the initial mass of the sodium chloride solution, 81.55% of the salt from the initial amount in the solution precipitates. The resulting salt contains 99.30% sodium chloride, 0.045% calcium, 0.011% magnesium, 0.07% sulfates, 0.03% potassium in terms of dry matter. Table salt from a pre-purified solution contains

99.68% sodium chloride. There are practically no organic substances in the salts. The main part of the organic matter is removed by leaching halite waste together with leaching solutions when obtaining technical salt, and residual amounts of organic substances remain on the filter when separating the nitrate. O. and sediments of accompanying impurities.

The results obtained formed the basis for the development of a technological scheme, a diagram of material flows and a material balance.

Figure 1 shows a flow diagram and material balance for processing flotation halite waste into table salt of food purity.

The processing process includes leaching of halite waste with a saturated solution of sodium chloride, obtaining technical sodium chloride and a saturated solution from this salt, purification of the solution from associated impurities, separation of water-insoluble residues, sediment of impurities and residual amounts of organic matter, evaporation of the purified solution, separation of table salt and its drying

To obtain 1000 kg of table salt of food purity, it is necessary to leach 1143.56 kg of halite waste with a saturated solution of sodium chloride at T:L = 1:1, the resulting pulp is divided into a precipitate of sodium chloride and a liquid phase containing potassium chloride by filtration. Wash the precipitate with a saturated solution of sodium chloride and dissolve in 3368.23 kg of water until a saturated solution is formed, clean from accompanying impurities of sulfates, magnesium and calcium, filter from n. o., precipitated impurities and residual amounts of organic matter. Evaporate the purified solution in the amount of 4413.75 kg, separate the wet sodium chloride salt in the amount of 1079.66 kg and dry it at a temperature of 100-120 °C.

Figure 1. Scheme of material flows and material balance for the production of food grade sodium chloride from flotation halite waste

In Fig. 2. The basic technological scheme for processing halite waste into table salt of food purity is given.

Figure 2. Schematic flow diagram for producing food-grade sodium chloride from halite waste 1 - leach reactor, 2, 5, 7 - filters, 3 - containers, 4 - solvent reactor, 6 - evaporator, 8 - drying drum, 9 - cooling drum, 10 - refrigerator

A saturated solution of sodium chloride, prepared from halite waste, is fed into the leaching reactor (item 1), where halite waste is simultaneously fed to leach potassium chloride from it. Next, the slurry from the reactor is fed to a filter to separate the liquid and solid phases. From the filter (item 2), the wet salt flows into the technical sodium chloride solvent reactor (item 4), and the mother liquor into the filtrate collector (item 3). Reagents for purification from impurities are supplied to the solvent reactor simultaneously with technical salt. A saturated solution of technical sodium chloride from the solvent reactor is supplied to the vacuum filter (item 5). The purified, saturated solution is fed through an intermediate container (item 3) into the evaporator (item 6). From the evaporator, the sodium chloride pulp enters the belt filter (item 7). Wet salt is supplied to the drying drum (item 8), cooling drum (item 9) and then to the warehouse. Juice vapors are cooled and fed to dissolve technical salt.

Table 1 shows the norms of the technological regime for processing flotation halite waste into food grade sodium chloride.

Table 1.

Technological standards

Name of parameters Meaning

1. Preparation of a saturated sodium chloride solution

Temperature, °C 20-40

Water, kg 2700

Halite waste, kg 1000

2. Potassium chloride leaching

Temperature, °C 20-40

Halite waste, kg 1143.56

Saturated solution No. C1, kg 1143.56

3. Separation of wet sodium chloride by filter

Temperature, °C 20-40

T:F pulp 1:1

Sodium chloride pulp, kg 2287.12

Saturated sodium chloride solution, kg 1000.78

Wet sodium chloride sludge, kg 1286.34

Vacuum during filtration, kgf/cm2 0.5-0.8

4. Preparation of a saturated solution of technical sodium chloride and its purification

Temperature, °C 50-70

Water, kg 3265.32

Halite waste, kg 1286.34

5. Department no. O. and impurities on the filter

Temperature, °C 50-70

Saturated solution No. C1, kg 4413.75

Wet sediment n. o., BaSO4, Mg(OH)2, CaС03, kg 137.91

6. Reduction of saturated sodium chloride solution

Temperature, °C 100-120

Saturated solution, kg 4413.75

Vacuum during filtration, kgf/cm2 0.6-0.8

7. Separation of wet sodium chloride by filter

Temperature, °C 90-100

T:F in the condensed part of the pulp 1:1.1

Evaporated sodium chloride pulp, kg 2233.05

Evaporated water, kg 2190.53

Saturated sodium chloride solution, kg 1153.39

8. Drying wet sodium chloride and cooling

Flue gas inlet temperature, °C 350-450

Flue gas outlet temperature, °C 100-150

Wet sodium chloride sludge, kg 1079.66

Moisture, kg 79.66

Dust fraction, kg 0.5-1

Dry sodium chloride, kg 1000

Cooling air temperature, °C 20-30

On a model installation simulating production conditions, at the Dekhkanabad Potassium Fertilizer Plant Unitary Enterprise, the technology for processing wet technical sodium chloride obtained from halite waste in industrial conditions using existing equipment for the production of flotation potassium chloride into food-grade sodium chloride was tested. A pilot batch of sodium chloride has been produced, characterized by the following quality indicators (wt. %): NaCI - 99.68; K2O - 0.03; H2O - 0.26; SO4, CaO etc. O. - absent.

The resulting samples of sodium chloride meet all the requirements for table salt of food purity in terms of the content of foreign inorganic impurities. Organic substances in the salt samples could not be detected by gas chromatography-mass spectrometry.

The results of the tests indicate the possibility of processing flotation halite waste from the Dekhkanabad Potash Fertilizer Plant into table salt of the highest grade of food grade purity. To do this, from the technical salt of sodium chloride obtained from halite waste, it is necessary to obtain a saturated solution of sodium chloride, clean it of impurities, evaporate the purified solution until moisture is removed in an amount of 50% of the original mass, separate the precipitated sodium chloride crystals and dry. This produces sodium chloride, containing 99.68% of the main substance and meeting the requirements of GOST 13830-91, the highest grade.

References:

1. Burriel-Marti F., Ramirez-Muñoz H. Flame photometry. - M.: Mir, 1972. - 520 p.

2. GOST 20851.3-93. Mineral fertilizers. Methods for determining the mass fraction of potassium. - M.: IPK Publishing House standards, 1995. - 32 p.

3. Kreshkov A.P. Fundamentals of analytical chemistry. In 3 volumes. T.2. Quantitative analysis. - M.: Chemistry, 1965. - 376 p.

4. Methods for the analysis of brines and salts / ed. Yu.V. Moracevsky and E.M. Petrova. - M. - L.: Chemistry. 1965. - 404 p.

5. Samady M.A., Yorboboev R.Ch., Boynazarov B.T. and others. The influence of technological parameters on the process of processing halite waste // Chemistry and chemical technology. - Tashkent, 2013. - No. 2. - P. 14-18.

6. Samady M.A., Mirzakulov Kh.Ch., Usmanov I.I. and others. Technology of processing halite waste from potassium production into technical sodium chloride // Uzbek chemical journal. - Tashkent, 2013. - No. 3. -S. 55-60.

7. Shubaev A.S., Krasheninin G.S., Rezantsev I.R. and others. Main directions of scientific and technological progress in the salt industry for 1986-1990. // Salt industry. Ser. 25. - 1986. - Issue. 4. - pp. 16-20.

1. Byurriel-Marti F., Ramires-Munos H. Photometry of flame. Moscow, "Mir" Publ., 1972, 520 p. (In Russian).

2. GOST 20851.3-93. State Standard 20851.3-93. Fertilizers mineral. Methods of definition of a mass potassium. Moscow, IPK Izdatel "stvo standartov Publ., 1995. 32 p. (In Russian).

3. Kreshkov A.P. Basis of analytical chemistry. V. 2. The quantitative analysis. Moscow, Khimiia Publ., 1965. 376 p. (In Russian).

4. Morachevskii Iu.V., Petrova E.M. Methods of the analysis of brines and salts. Moscow-Leningrad, Khimiia Publ., 1965. 404 p. (In Russian).

5. Samady M.A., Yorboboev R.Ch., Boynazarov B.T., Mirzakulov Kh.Ch. Influence of technological parameters on processing process halite waste. Khimiia I khimicheskaia tekhnologiia. Tashkent, 2013, No. 2. pp. 14-18. (In Russian).

6. Samady M.A., Mirzakulov Kh.Ch., Usmanov I.I., Boynazarov B.T., Rakhmatov Kh.B. Technology of processing halite waste of potassium manufacture to technical sodium chloride. Uzbekskii khimicheskii zhurnal. Tashkent, 2013. No. 3. pp. 55-60. (In Russian).

7. Shubaev A.S., Krasheninin G.S., Rezantsev I.R., etc. The Basic directions of scientific and technical progress in the hydrochloric industry for 1986-1990. Solianaia promyshlennost". Seriia 25. 1986. series 25. Issue 4. pp. 16-20 (In Russian).

Salt production is a complex multi-stage process, consisting of the extraction of raw materials, purification from mechanical and chemical impurities, enrichment with useful elements, drying and crushing. To obtain a quality product you need modern equipment and strict adherence to technology.

The technology and process of salt production, in turn, depend on the type of deposit and the characteristics of the product: purity, granule size, presence of additives. Let's talk about everything in more detail.

Main methods of salt extraction and production

The most common options:

Closed mine method. This is how 60% of all salt in the world is mined. Solid sodium chlorine, located in the bowels of the planet, forms mountains. Their bases are five to eight kilometers deep, and their domed tops can be visible on the surface of the earth. To extract such salt, long tunnels are cut. There are many chambers and galleries branching off from the main tunnel. All this is built using road boring machines or cutting machines. In order to get the salt to the surface, it is immersed in scraper installations. Next, to facilitate and speed up the process, large pieces are cut into small pieces and sent on trolleys or elevators to the processing workshop. Here sodium chlorine is ground, purified (if necessary) and packaged. The advantage of mine production is that it does not depend on the season. Production doesn't stop all year round.
In-situ leaching. Groundwater erodes the salt layers, resulting in a natural solution. It is pumped out and then evaporated. Also, in some cases, leaching is carried out artificially: taking into account the location of the deposits, a network of wells is laid. They pump through them hot water, which dissolves sodium chlorine, is then pumped out with slurry pumps into vacuum tanks with reduced pressure. Here the water evaporates and the crystals settle to the bottom. The sediment is ground in a centrifuge. This method of producing table salt is relatively inexpensive.
Career method. Sodium chlorine is mined in open pits from the bottom of salt lakes or mines. This material is of low quality and at an affordable price. The purity of the extracted NaCl does not exceed 90%. Most often, quarry salt is used as a base for de-icing reagents, as well as for other technical purposes.
Evaporation. Lake and sea salt are evaporated artificially, or sodium chlorine that has already precipitated naturally is extracted. The disadvantage of this method is its strong dependence on the vagaries of nature.

Depending on the extraction method, the following types of salt are distinguished:

stone- extracted by mine or quarry method from sedimentary rocks;
evaporation- obtained by boiling artificial or natural brines;
cage- evaporated in special pools with lake or sea water;
self-planting- deposits itself, it is collected with a special pump from the bottom of the lake.

More than 95% of sodium chlorine mined in the Russian Federation is self-salting and rock salt.

Differences in production technologies for technical, food and feed salt

Obtaining technical salt

This salt is delivered from the deposit, purified from solid halite waste in a metal collector, and crushed to obtain the desired size. If necessary, products are treated with an anti-caking agent.

Production of table salt

Consists of the following stages:

Cleaning. Halite goes through several washes, then it is crushed and unnecessary metal impurities are removed using a special separator.
Drying produced using an industrial centrifuge.
Crushing. The salt is sent to a vibrating conveyor, where the granules acquire the desired size.
Final drying produced in a furnace where hot air is blown by an industrial fan.

Feed salt production process

Lick salt is made from pure self-planting salt on special machines. Crystalline sodium chloride is poured into trays, where under pressure they turn into a briquette, similar in density to stone. Another option for making briquettes is to use a vibrating table.

Production of tableted salt

Highly purified raw materials are used to make tablets. The sodium chlorine content reaches 99.7%. The product is obtained by evaporation on special equipment, dosing and pressing into tablets.

As you know, bread, salt and water are the “three pillars” of the food world, which you cannot do without and which will always be sold in large volumes. In fact, a business based on the production of table salt is an inexhaustible source of income. Despite the low selling price, there is a wide market for the final product and constant demand guarantee very good profits.

Naturally, having the necessary financial capabilities, even a small start-up enterprise can master the independent extraction of halite (rock salt). The main condition is the proximity of the location to the immediate place of development of halite deposits, in order to minimize transportation costs, which significantly affect the cost of the finished product.

There is an alternative way to obtain table salt - by evaporating it from sea water or saline lakes and ponds. But normal profitability in this case is ensured only by very large production volumes and the presence of the above-mentioned reservoirs in the region.

If there is no opportunity or desire to extract it yourself, you can build a profitable, quick-paying business by processing, packaging and subsequent sale of table salt.

Technological process for producing table salt from halite

The first stage - the extracted salt is cleaned from foreign impurities in a magnetic separator and undergoes a two-stage washing process. Dried in an industrial centrifuge, the purified mass enters a vibrating sieve and a roller crusher for grinding to large and small sizes. Iodine is added in a special apparatus.

If necessary, at the same stage, various additives and useful substances are added to the salt, such as, for example, potassium ferrocyanide, which prevents the formation of lumps, iodides, fluorides (to prevent dental problems). Final drying takes place in an oven using a jet of hot air provided by an industrial fan.

A second powerful fan cools the salt. Next, along a belt and spiral conveyor, the processed product enters the packaging and packaging line.

Equipment and personnel

The cost of an automatic line for the production of table salt directly depends on the productivity and its functionality.

There is no need to purchase expensive European equipment. A Chinese-made line with a capacity of one ton per hour with proper installation and timely maintenance copes with the task quite well.

Equipment that allows you to produce exceptionally coarse edible salt will cost 230-250 thousand dollars. A universal installation that outputs both coarse and fine salt, plus iodized and without iodine additives - 350,000 USD. Naturally, the wider the range of products, the greater the income of the enterprise.

Maintenance will require a staff of 3-5 people.

The conveyor line for the production of edible table salt can be purchased either assembled or purchased separately.

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Equipment cost:

Magnetic separator - $750;

Crusher – $12,000;

Interfering and spiral sinks – $23,000;

Industrial pumps for salt and brine – $9900;

Spiral and belt conveyors – $12,500;

Industrial centrifuge – $40 thousand;

Iodization unit – $6600;

Vibration drying – 22000 USD;

Furnace with fan - $24,000;

Cooling fan – $780;

Hoods, dust extractor - $7900;

Tanks, containers, and bunkers for salt and solutions will also be needed.

Business prospects

Today, in addition to linear business expansion, there are several additional prospects and directions related to salt production.

The first, borrowed from Western colleagues, is the production of table salt with the addition of potassium chloride, magnesium chloride and with a minimum sodium content.

The second is the processing of salt not only as a food additive, but also for the needs of the chemical industry.

Third, it is not necessary to limit the production and mining cycle exclusively to rock salt; sylvinite is also found in nature - rock, which serves as a raw material for the production of potassium chloride. The latter is actively used in agriculture in the production of potash fertilizers and salts.

Unpurified brine from the brine production facility continuously flows into the crude brine tank pos. E18 with a capacity of 2000 m3. From the reservoir with centrifugal pumps type X 200-150-400 pos. H29 is supplied for heating to a group of heat exchangers. In heat exchangers pos. T4 brine is heated to 40°C due to the heat of the condensate of the secondary steam of the evaporators.

Having passed the heating unit, the brine enters the central part of the settling tank stabilizer, pos. X10, where it is mixed with a soda-caustic reagent and a PAAG working solution. The piping scheme for settling tanks provides for their operation in autonomous and sequential mode. The soda-caustic reagent is supplied in an amount of 0-8 m3/hour.

After mixing the crude brine and the caustic soda reagent, poorly soluble compounds are formed: calcium carbonate CaCO3 and magnesium hydroxide Mg(OH)2. The solubility of calcium carbonate decreases with increasing temperature and therefore, to reduce the residual content of calcium ions, it is recommended to purify the brine at a temperature of 30-40ºC. In addition, with increasing temperature, larger and more easily settling calcium carbonate crystals are formed, which is very important for the subsequent settling of the brine.

The purified brine must contain:

CaI+ ions no more than 0.05 g/dm³;

MgI+ ions no more than 0.04 g/dmі;

excess СО3ІЇ no more than 0.15 g/dmі;

excess OH is not more than 0.1 g/dm3.

In the settling tank, CaCO3 and Mg(OH)2 are formed and the brine is clarified from these sediments. Single-tier settling tanks with a central paddle drive and a central input of the settled liquid.

Through a drain funnel installed in the upper peripheral part of the drain chute of the settling tank (in sequential operating mode), the clarified brine flows by gravity into the purified brine tanks pos. E20 with a capacity of 2000 m3 each.

To intensify the settling process of the purified brine, PAAG is used with a working concentration of 0.001-0.1%, which is supplied to thickener settling tanks by pumps pos. H30. Sludge from the settling tanks, thickening, continuously descends into the sludge collection pos. E19. Sludge from collectors, partially diluted with water 1:10 to a solid phase concentration of up to 18%, goes to a sludge storage facility.

Brine purified from calcium and magnesium salts in an amount of up to 240 m3 from tanks using centrifugal pumps type X280/29T pos. H32 is supplied to the evaporation department and in an amount of 25-100 m³ per shift to the reagent department for the preparation of reagents.

The evaporation department has three evaporation units, including one backup.

Initial purified brine in quantities up to 240 m3/hour (based on two working evaporation units) with a temperature of 18-35ºC from tanks with pumps type X 280/29-T pos. H32 is supplied to the nutrient tanks pos. E21 with a capacity of 100 m³ each, part of the purified brine in the amount of 25-40 m³/hour is sent to the centrifugation department for washing the salt in Brandeis thickeners and centrifuges.

The feed tanks also receive recirculating mother brine in the form of part of the discharge from Brandeis thickeners and centrifuge centrifuge.

A mixture of the initial purified brine with the recirculating mother brine necessary to remove the solid phase from the installation, called feed brine, is supplied respectively to each evaporation unit, pos. K6 in parallel to all evaporators.

Before feeding into the evaporator, the feed brine is heated in a shell-and-tube heat exchanger pos. T5 with a heat exchange surface of 75 m².

Heating of the feed brine before feeding it into 1 evaporator of the evaporator unit is carried out by condensate of the heating steam of 1 housing and secondary steam of 2-4 housings. The brine moves through the pipe space, condensate from the heating chambers moves through the interpipe space. The main flow of the feed brine is supplied to the irrigation rings located in the upper part of the separators of the evaporators; a small part of this brine in the amount of 2-4 m3/hour is supplied to each of the surge tanks to prevent the deposition of table salt on them.

During evaporation in the apparatus, crystallization of table salt occurs, and the flow rate of the supply brine into each apparatus is set so that the mass fraction of the solid phase in the evaporated suspension (pulp) of each evaporator is equal to 30-40%. At mass fraction Below 30%, the cost of heating steam to produce salt increases and salt deposits form on the walls of the separator of the evaporator, which leads to a reduction in the inter-flushing period of operation of the evaporator. At a mass fraction above 40%, heat transfer in evaporators deteriorates and the productivity of the evaporation unit decreases, in addition, the size of table salt crystals decreases.

The evaporated pulp flows from body to body by gravity through the overflow tank. This is facilitated by a consistent decrease in pressure throughout the housings. A decrease in pressure leads to partial self-evaporation of the solution in subsequent housings and additional release of secondary steam in them.

From the fourth (last) evaporator, production salt pulp containing 30-40% wt. crystalline table salt, in the amount of 60-90 m3/hour with a pump type GrT 160/31.5 pos. H31 is pumped into the centrifugation department into Brandeis type thickeners, pos. X11.

The pressure in the heating chamber of the first evaporator is maintained in the range of 0.15-0.22 MPa. Steam consumption per evaporation unit is up to 30 t/hour.

Secondary steam from the first evaporator enters the heating chamber of the second evaporator, the pressure in which should not exceed 0.7 MPa. Subsequent evaporators are heated by secondary steam from the previous evaporator. From the fourth evaporator, secondary steam enters a barometric condenser with a diameter of 2.0 m.

The condensate from the heating steam of the first evaporator is cooled in heat exchangers, then pumped to the boiler room.

The secondary steam condensate from the heating chamber of the second evaporator enters the heating chamber of the third evaporator, and then from it into the heating chamber of the fourth evaporator, from where it is supplied for other production needs.

To utilize vapors and non-condensed gases in barometric condensers, recycled water with a temperature not exceeding 28°C is used. Heated water from barometric condensers enters tanks - hydraulic seals with a capacity of 10 m3 each with a temperature not exceeding 50 ° C and is then supplied to fan cooling towers. The chilled water is collected in a cold water receiver and is sent for vapor recovery in barometric condensers.

Non-condensable gases from the heating chamber of the first evaporator are discharged into the heating steam pipeline of the second evaporator. From the heating chamber of the second evaporator, non-condensable gases are discharged into the heating steam pipeline of the third evaporator, from the third heating chamber into the heating steam pipeline of the fourth evaporator, and from the fourth heating chamber into the barometric condenser. The outlet is carried out through a central pipe located in the interpipe space of the heating chamber.

Thickening of salt pulp from 30-40% to 40-60% of the mass. the solid phase is carried out in thickeners of the Brandes type, and the separation of the solid phase is carried out in horizontal filter centrifuges of type S FGP 1201T-01 pos. Ts23 with pulsating sediment unloading. Washing the salt from the mother brine is done with purified brine in Brandeis type thickeners. The consumption of purified brine for washing is 25-35 m 3 /hour. Washed and centrifuged salt with a moisture content of 2-3% wt. enters conveyor belts. Wet salt on the conveyor is treated with a solution of potassium ferrocyanide (PFC) as an anti-caking agent.

The FCC solution is prepared in a tank, into which a sample of crystalline potassium ferrocyanide, condensate and compressed air are supplied to mix and dissolve the FCC. From the tank, the FCC solution flows by gravity through a pipeline through nozzles to the wet salt conveyor, pos. PT 24. Passing along the conveyor, the salt is partially mixed and supplied for drying.

The flow rate of the FCC solution is regulated automatically, depending on the amount of salt entering the conveyor. Salt consumption is determined using scales (indicator scales) on the conveyor.

Wet table salt containing 2.5 ± 0.5% wt. H2O and a temperature of 40 ±5 °C are distributed by conveyors into bins pos. X12. From the bunker, table salt is fed by a feeder and a mechanical thrower into the “fluidized bed” apparatus, pos. T3, where salt is dried with hot air. Air is supplied to the apparatus by a pipe-gas blower after preheating in the air heater pos. T1.

Air is supplied to the air heater in an amount of 11000 ± 2000 nm/h per drying unit at a pressure of 4000 ± 500 Pa.

In an air heater, the air is heated by flue gases from combustion natural gas in burners type GMG - 2 M firebox pos. T 2. When the gas is turned off, high-sulfur fuel oil grade M-100 can be used as fuel. Before combustion, fuel oil is heated with steam at a pressure of 0.6 MPa to 120°C. Air for combustion of fuel oil, gas (to the burner), for cooling of the furnace roofs and after-combustion is supplied by a VDN type fan - 11.2 pos. At 33-34 under a pressure of 2000 ±500 Pa. In this case, the air consumption for the burners is 5000 ± 1000 nmі/h, and for blowing the roofs and afterburning - 1600 ± 200 nmі/h.

The combustion of natural gas or fuel oil in the furnace occurs at a vacuum of 50 ± 20 Pa and a temperature of up to 1300°C. The specified vacuum is maintained by a smoke exhauster pos. B36.

A decrease in vacuum can lead to the release of hot flue gases into the room; an increase in vacuum leads to increased suction of cold air into the firebox, which can lead to a torch failure.

Flue (smoke) gases in the mixing chamber of the firebox pos. T2 is mixed with waste (after the air heater) return flue gases having a temperature of 180 ± 10°C. As a result of mixing, the temperature of the flue gases decreases to 550 ± 50°C, at this temperature they enter the pipe space of the air heater through underground ducts to heat the drying agent, where they are cooled from 550 ± 50°C to 180 ± 10°C, and are pumped into the packed adsorber pos. K8, where gases are purified from sulfur-containing compounds, after which the latter are purified by a smoke exhauster type DN - 12.5 N = 75 kW, n = 1500 rpm with a capacity of 37,000 m³/h pos. X13 is emitted into the atmosphere through a common flue and two chimneys with a diameter of 600 mm. The height of the first chimney is 45 m, the height of the second chimney is 31.185 m. A decrease in the temperature of the flue gases below 170°C leads to the formation of acid corrosion of gas pipelines and chimneys, and an increase in temperature above 200°C leads to failure of the smoke exhauster. Part of the cooled flue gases is supplied by the same smoke exhauster to the mixing chamber of the firebox to maintain their temperature in front of the air heater in the range of 550 ± 50°C.

Adsorber pos. K8 is irrigated with soda. The wastewater generated in this case is sent to the industrial waste collection facility, pos. E16, from where they are discharged into the sewer.

Dried table salt from the "KS" apparatus through the overflow chute is supplied to the "KS" apparatus for cooling. Cooling air is supplied to the device by a fan. Chilled table salt is unloaded onto the conveyor pos. PT27, from where it is supplied to vertical elevators type TsG - 400 pos. PT28 and further to electromagnetic vibrating screens to separate the pellets formed during drying.

Large salt particles (more than 1.2 mm) and lumps that did not pass through the holes in the sieve fabric of vibrating screens pos. E22, leave it and, by gravity, in an amount of 320 ± 50 kg/h enter a vertical mixer with a capacity of 10 m³ to dissolve the pellet, pos. E14.

The resulting solution in an amount of 3-6 m and 5-10% is pumped out by pumps type AX 45/54 into the industrial waste collector, pos. E15.

At the unit for transferring salt from vibrating screens onto conveyors, magnetic traps are installed. The installation was carried out in 2 tiers: the top -3 magnets, the bottom -4 magnets. The main flow of salt with particle sizes less than 1.2 mm is supplied to inclined belt conveyors KLS - 800 positions. PT26, supplying salt to the salt packing and packing shop.

The dusty air leaving the "KS" apparatus enters the gas cleaning system. Cleaning is carried out in two stages: preliminary cleaning of the largest particles is carried out in cyclones pos. K7 and cleaning from fine dust particles in a bag filter pos. F9.

The spent drying agent with = 70 ± 10°C and dust content of 12-50 g/nm under a discharge of 200 ± 50 Pa is supplied to the battery cyclone for cleaning. Air purified in a battery cyclone to a concentration of 12-17g/nmі t=68±8єС in the amount of (16±4)x10і nmі/hour under a discharge of 1500±500Pa is sucked in by a fan pos. B35 and is supplied under a pressure of 4500±500 Pa for cleaning into a bag filter.

Salt dust is removed from the battery cyclones using chutes equipped with flashing lights (sluice gates) and fed into the container pos. E17, where recycled water flows. The resulting saline water is directed to a pit located in the brine field. Fine dust collected in a bag filter is fed to a belt conveyor pos. PT25, from where it enters the pellet washout tank.

The spent drying agent, finally cleared of the smallest particles of salt dust, at a temperature of 110°C is supplied to the air heater pos. T1, where it is heated to a temperature of 300°C and returned to the “KS” dryer.

The process flow diagram for the production of sodium chloride is presented in Appendix C.

Having chemical formula"sodium chloride", used as food product and is of great importance for the life of humans and other creatures. Table salt has white crystals because it undergoes several processing steps during production. Although salt of natural sea origin has brown and gray shades due to the content of impurities. Produce salt different types: pure, iodized, nitrite.. Salt is divided into grades depending on purity: extra, highest, first and second.

Salt extraction technologies

There are various salt extraction technologies. Self-settling salt technology consists of extracting salt from “salt waterfalls” by natural evaporation of seawater from caverns. Sad salt is mined from the depths of salt lakes or in salt cave lakes. The extraction of cage salt is carried out during the warm season in areas with a suitable climate through the natural evaporation of cage brine in artificial flat pools. In regions with cold climates, the freezing method is used. Rock salt is extracted by mining and is not subjected to heat or water treatment. Evaporated salt is extracted by evaporation from salt solutions (from natural underground brines or rock salt layers obtained by pumping water through drill holes. Salt is also extracted by purifying halite (rock salt), deposits of which are located on the site of dried up seas.

Previously, in ancient times, salt was extracted by burning certain plants doused with sea water - hazel and deciduous trees. The resulting ash was used as a seasoning. The very first saltworks were found in Bulgaria. In the 6th millennium BC, salt was evaporated in massive dome-shaped adobe ovens.

Today, salt is used not only for food purposes, but also for industrial and technical purposes. Technical salt is used for chemical production. Table salt is also used to produce soda, chlorine, hydrochloric acid, sodium hydroxide and sodium metal. The healthiest one is sea salt, which contains many minerals. Today, the choice of salt processing and production technology depends on its type.

Salt production technology

Table salt is obtained from halite. Halite (or rock salt) is a mineral and may contain various impurities, sand, earth, and metal particles. In the technology for the production of table salt, after the development of halite deposits, the raw material goes through several stages of purification, then washed, crushed, and finally washed 2 more times. On the production line, a magnetic separator sifts out metal impurities. At the final stage, the salt is dried in a special centrifuge.

Iodized salt is obtained by adding iodine to a purified semi-finished product. The salt is then sent to a dryer and crusher if fine iodized salt is required. If you want to obtain coarse iodized salt, then the crushing process is skipped. During the drying process, it is possible to add other auxiliary substances, for example, anti-caking agents, fluorides, iodides and carbonates. In accordance with the standard, the content of food additives should not exceed 2-3%. Then the products are packaged and packaged.

Salt is also used in the production of polymers and plastics, in the oil industry (for defrosting soil), in the production of soap, paper, glass, in animal husbandry, as well as for other technical purposes. Such a popular product is a very promising line of business today.

Production of table salt. Table salt

Annotation scientific article on industrial biotechnologies, author of the scientific work - Samady Murodjon Abdusalimzoda, Mirzakulov Holtura Chorievich, Rakhmatov Khudoyor Boboniyozovich

Related topics scientific works on industrial biotechnologies, author of the scientific work - Samady Murodjon Abdusalimzoda, Mirzakulov Holtura Chorievich, Rakhmatov Khudoyor Boboniyozovich

Text of scientific work on the topic “Technology of table salt of food purity from halite waste from potash production”

Main methods of salt extraction and production

Differences in production technologies for technical, food and feed salt

Obtaining technical salt

Production of table salt

Feed salt production process

Production of tableted salt

Salt extraction technologies

Salt production technology