WO2014168599A1

WO2014168599A1 - Method for processing solid waste from the chemical purification of brines

Info

Publication number: WO2014168599A1
Application number: PCT/UA2013/000143
Authority: WO
Inventors: Валерий Иванович СЕМЕНИЙ
Original assignee: Semenii Valerii Ivanovych
Priority date: 2013-04-10
Filing date: 2013-12-06
Publication date: 2014-10-16
Also published as: UA103292C2

Abstract

The invention relates to the field of inorganic chemistry and is intended for processing waste from the chemical purification of brines in the production of sodium chloride (NaCl) from brines. The invention is novel in that the solid waste from the chemical purification of brines in the production of sodium chloride includes calcium carbonate (CaCO3) and magnesium hydroxide (Mg(OH)2), and the feedstock is diluted with water to produce a suspension which is then subjected to carbonation to produce a brine comprising magnesium hydrogen carbonate (Mg(HCO3)2) and calcium carbonate (CaCO3), following which the calcium carbonate is removed from the brine using a filter press and subsequently dried, and the remaining brine is fed into a decarbonation process, whereby basic magnesium carbonate is precipitated (3MgHCO3*Mg(OH)2), which is then calcined at a temperature of 350-400°С, and an active magnesium oxide (MgO) is liberated, wherein the heating process in a calciner is carried out by using the heat from a condensate from evaporating apparatus of steam-boilers.

Description

METHOD FOR PROCESSING SOLID WASTE OF CHEMICAL CLEANING

Saline brines

The invention relates to the field of inorganic chemistry and is intended for the treatment of waste products for the chemical treatment of salt brines in the production of sodium chloride (NaCl) from salt brines. A known method of producing magnesium oxide, according to which talc magnesite is used as raw material or talc enrichment waste from talc magnesite ores, the raw material is calcined to decarbonize magnesium carbonate, the obtained magnesium oxide is converted to water-soluble magnesium hydroxide by carbonation under conditions increased pressure, hydroxide - magnesium carbonate is precipitated from the solution during heating, the precipitated precipitate is separated and calcined at a temperature of 900-1 100 ° С to obtain pure magnesium oxide I (RU 2372289 C1, 10.11.2009).

The disadvantages of the analogue include the fact that during the implementation of the method they use firing of raw materials, this leads to the emission of harmful greenhouse gases into the atmosphere, harmful waste remains that are disposed of in landfills, all this pollutes the environment, in addition, significant energy resources are used to implement the method.

The closest in technical essence to the claimed invention is the prototype method of producing magnesium carbonate together with calcium carbonate and sodium sulfate, where it is used sludge of purified alkaline waste, which consists in the fact that the waste is washed, precipitated and filtered, the filtrate is fed to carbonization, then the calcium carbonate is filtered off, then the filtrate is heated and laid out with the precipitation of magnesium carbonate (CN 102070163 A, 05.25.2011).

In the known method, liquid solutions of soda waste are processed, its disadvantages are the use of sodium carbonate, a large amount of water for washing from chlorides, while water with washed chloride and sulfate ions gets into the settlers, harmful substances pollute the environment. High-temperature heating causes the release of greenhouse gas (carbon dioxide), while a large amount of energy is consumed (heating the liquid phase to a temperature of 100-105 ° C), and sophisticated technological equipment is used (washing devices, carbonization columns, drying centrifuges, sludge traps).

The basis of the invention is the task of creating a method for processing solid waste of chemical cleaning of salt brines in the production of sodium chloride, by stopping the emission of polluting harmful waste and obtaining products useful for the industry - calcium carbonate (CaCO3) and magnesium oxide (MgO), reducing heat load on the environment, which ensures environmental friendliness of waste processing, in addition, energy resources are effectively used, which increases the technological efficiency of the method.

The problem is solved due to the fact that in the method of processing solid waste of chemical cleaning of salt brines in the production of sodium chloride, which consists in diluting water with raw materials with further carbonization, subsequent precipitation of the precipitate, its calcination, decarbonization of the remaining brine and annealing of the separated precipitate, characterized in that solid waste chemical purification of salt brines in the production of sodium chloride contains calcium carbonate (CaCO3) and magnesium hydroxide (Mg (OH) 2), the feedstock is diluted with water to obtain a suspension, which is carbonized to form a brine containing magnesium hydrogen carbonate (Mg (HCCb) 2) and calcium carbonate (CaCO3), after which calcium carbonate is separated from the brine on a press filter, it is dried, and the remaining brine is fed to decarbonization, where a precipitate of basic magnesium carbonate (3MgHC03 * Mg (OH) 2) is formed, which is calcined at a temperature of 350-400 ° C and secrete active hydroxy Magnesium (MgO), heating is carried out in the calciner condensation heat of evaporation apparatuses boilers.

As raw materials, solid waste from chemical cleaning of salt brines is used: calcium carbonate (CaCO3) and magnesium hydroxide (Mg (OH) 2), they remain in the process of producing salt - sodium chloride (NaCl), which is carried out according to a known method as follows. Water is fed into a well drilled in a salt formation, and a saturated brine of salt is obtained, which is supplied for treatment. The following ions are contained in the brine: Na ⁺ , Ca ²⁺ , Mg ²⁺ , Sr ²⁺ , SG, S04 ^{2 "} , which form the following compounds: NaCl, CaCh, CaS04, MgCh, MgSCU, SrSO, BegOz. This brine is pre-purified from ions of calcium, magnesium, strontium, iron oxides. Then it is purified from sulphates through filters and iron oxides are removed on a magnetic separator. The brine thus purified is fed for final purification, during which caustic NaOH and soda ash Na2C03 are added. After the reaction, CaCO3 carbonate and magnesium hydroxide Mg (0H) 2 - solid precipitate NaCl production waste.

Thanks to the inventive method, the full use of solid waste products of NaCl production, which were previously disposed of in a landfill, is provided, these waste products are processed, and products useful for the industry are obtained - calcium carbonate (CaCO3) and magnesium oxide (MgO). s Dilution with water of solid wastes containing calcium carbonate (CaCO3) and magnesium hydroxide (Mg (OH) 2) to obtain a suspension allows these substances to be suspended to further carbonization in order to convert insoluble magnesium hydroxide (Mg (OH) 2) to soluble magnesium bicarbonate (Mg (HC03) 2) in the state of brine. This makes it possible to separate calcium carbonate (CaCO3) from brine, that is, without the use of aggressive chemicals, to isolate from the environmentally harmful waste a useful product - calcium carbonate (CaCO3). Decarbonization of the remaining brine allows the transfer of soluble magnesium bicarbonate (Mg (HC03) 2) to the precipitate of basic magnesium carbonate 3MgHC03 * Mg (OH) 2.

Calcination of the precipitate is carried out at a temperature of 350-400 ° C, which is sufficient for its complete decomposition and production, without excessive thermal load of the environment, a useful product - active magnesium oxide (MgO). Thus, in the implementation of the proposed method, they fully recycle solid waste products of NaCl production, which were previously disposed of in a landfill, while they do not use aggressive chemicals, reduce the heat load on the environment. Due to the fact that the substances that are necessary for the implementation of the proposed method have a low temperature regime for their conversion, they use secondary energy resources: the heat of the condensate of the evaporation apparatus of steam boilers, this increases the technological efficiency of the method and simplifies the process as a whole. When using the proposed method there is no need to use expensive energy, use expensive equipment, furnaces, thickeners.

The implementation of the proposed method is illustrated in the drawing. The drawing shows a diagram of devices for implementing the method of processing solid waste chemical cleaning of salt brines in the production of NaCl salt.

The scheme consists of a tank 1 for diluting solid waste with water, the outlet of which is connected to a carbonizer 2, to which flue gas is supplied. The output of the carbonizer 2 is connected to a press filter 3, one output of which is connected to the decarbonizer 4, and the second output of the press filter 3 is connected to thermal devices for drying 7, to which flue gas is supplied. The input of the crusher 8 is connected to the thermal device for drying 7. The output of the decarbonizer 4, to which the condensate heat of steam boilers is supplied, is connected to the press filter 5, the output of which is connected to the thermal devices for calcination 6.

The method is as follows. 600 kg of solid waste of chemical cleaning of salt brines are loaded into tank 1: CaCO3 carbonate and magnesium hydroxide Mg (OH) 2, and 2400 l of water to dilute these solid waste to a suspension state. The resulting suspension is fed into carbonizer 2, where boiler house flue gas enters to saturate the suspension with carbon dioxide, moreover, 1 liter of suspension is fed with 0.5 l of gas per minute for 1.5 hours. After carbonization, soluble magnesium bicarbonate (Mg (HC03) 2) and a precipitate of calcium carbonate (CaCO3) are obtained in the form of a brine with a density of 1.02 g / l. The brine is fed to a press filter 3, where the precipitate of calcium carbonate (CaCO3) is separated and fed to a thermal appliance for drying 7, into which the flue gas of the boiler houses with a temperature of 130 ° C is fed. The precipitate of calcium carbonate (CaCO3) is dried in a final moisture content of 0.5% and sent to a grinder 8, where it is ground to a fraction of 1-2 microns. The amount of calcium carbonate, namely: chemically precipitated chalk, which meets the requirements of GOST 8253-79, is 564 kg. Brine, the remaining after passing through the press filter 3, enters the decarbonizer 4, which serves the heat of the condensate of the evaporation apparatus of steam boilers. At a temperature of 50 ° C, soluble magnesium bicarbonate (Mg (HC03) 2) is transferred to a precipitate of basic magnesium carbonate 3MgHC03 * Mg (OH) 2 in a decarbonizer to form finely dispersed crystals, which are fed to a press filter 5 and then fed to a thermal device 6 for calcination, where the temperature is set to 350-400 ° C and active magnesium oxide (MgO) is released, which meets the requirements of GOST 4526-75, in the amount of 36 kg.

b

Claims

CLAIM

1. The method of processing solid waste chemical cleaning of salt brines in the production of sodium chloride, which consists in diluting water with raw materials with further carbonation, subsequent precipitation of the precipitate, calcining it, decarbonizing the remaining brine and calcining the separated precipitate, characterized in that the solid waste chemical cleaning of salt brines in the production of sodium chloride, they contain calcium carbonate (CaCO3) and magnesium hydroxide (Mg (OH) 2), the feedstock is diluted with water to obtain a suspension, which is subjected to carbon before the formation of a brine containing magnesium hydrogen carbonate (Mg (HC03) 2) and calcium carbonate (CaCO3), then calcium carbonate is separated from the brine on a press filter, it is dried, and the remaining brine is fed to decarbonization, where a precipitate of basic magnesium carbonate is formed ( 3MgHC03 * Mg (OH) 2), which is calcined at a temperature of 350-400 ° C and release active magnesium oxide (MgO).

2. The method according to claim 1, characterized in that the heating in the decarbonizer is carried out by the heat of the condensate of the evaporation apparatus of steam boilers.

SUBSTITUTE SHEET (RULE 26)

FIG.