WO2002002833A2

WO2002002833A2 - Preparation of pure ferric chloride from hydrochloric acid solutions by solvent extraction

Info

Publication number: WO2002002833A2
Application number: PCT/RU2001/000231
Authority: WO
Inventors: Leonid Irineevich Sklokin; Vladimir Trofimovich Kalinnikov; Walter Sieckman; Satish Wadhawan
Original assignee: Leonid Irineevich Sklokin; Kalinnikov Vladimir Trofimovic; Walter Sieckman; Satish Wadhawan
Priority date: 2000-06-19
Filing date: 2001-06-18
Publication date: 2002-01-10
Also published as: AU6964101A; WO2002002833A3; WO2002002833B1

Abstract

The present invention relates to a field of preparing high-purity ferric chloride from hydrochloric solutions containing impurities. More specifically the invention concerns a ferric iron extraction from water solutions as a result of concentrated hydrochloric acid interaction with iron-containing concentrates, as a result of multi-stage extraction of ferric chloride from solutions of complicated composition and due to processing of industrial wastes, including spent etching solutions of metallurgical plants after chlorination. The essence of the invention is that the proposed method includes two stages of concentration, extraction, and stripping steps. As an extracting agent use is made of aliphatic alcohol, predominantly octanol-1, octanol-2, 2-ethylgexanol, and decanol-1 or their mixtures. The alcohol content in organic phase is up to 100 %. Attained technical result consists in obtaining high-purity ferric chloride solution with not less than 300 kg/m3 FeCl3 concentration. Ferric chloride recovery is 96-98 % irrespective of the nature of impurities present in a feed hydrochloric solution concurrently with the limitation of waste solutions and optimization of material flows and equipment used. The resulting ferric chloride solutions are feasible for further processing in high performance installations of spray roasting which permit combine in one process receiving of high-purity ferric oxide and regenerated hydrochloric acid of high concentration.

Description

A METHOD FOR PREPARING FERRIC CHLORIDE SOLUTION

The present invention relates to a field of preparing high-purity ferric chloride from hydrochloric acid solutions containing impurities. More specifically the invention concerns a ferric iron extraction from water solutions originating as a result of concentrated hydrochloric acid interaction with iron-containing concentrates, as a result of multistage extraction of ferric chloride from solutions of complicated composition and due to processing of industrial wastes, including spent etching solutions of metallurgical plants after chlorinating the solutions.

Recovery of ferric chloride from hydrochloric acid solutions containing impurities faces the problem of purity increasing of the resulting ferric chloride solutions concurrently with affording an increased yield of ferric iron irrespective of the nature of impurities present in a feed solution. At rather high concentrations of hydrochloric acid and hydrogen ions, ferric chloride is well extracted by organophosphoric compounds, in particular tributyl phosphate (TBP), to yield fairly pure product practically free from silicon and calcium impurities. However, it is quite impossible to eliminate zinc and phosphorus impurities, the last being a decomposition product of TBP. Problem also arises while providing high (up to 350 kg/m³ and more) concentration of pure ferric chloride in resultant solutions with a view to their possible further processing in modern high-performance installations of spray roasting which permit to combine in one process receiving a regenerated hydrochloric acid of high concentration and pure feme oxide, in particular, for production of high-purity ferrites. Commercial use of extraction technology makes it necessary to limit volume of waste solutions and optimize material flows and capacity of working equipment.

A method is known for preparing ferric chloride solution (see US patent No. 4 490 338), which consists in extracting ferric chloride from a feed aqueous chloride solution containing not less than 18 kg/m³ of hydrochloric acid, not less than 10 kg/m³ of ferric chloride, at least one of the elements Zn, Cu, Mn, Co and Ni, and also hexavalent molybdenum and /or pentavalent vanadium. An aqueous solution of ferric chloride is contacted with organic phase containing as an extracting agent, in volume percent: 10-60 of tributyl phosphate, 40-55 of isodecanol as an antiemulsion agent, and up to 50 of kerosene as an inert diluent. Isodecanol fulfills also the function of an extracting agent. Extraction is carried out with an organic to aqueous phase ratio equal to 1.20-1.32:1. Iron-filled organic phase is separated from an aqueous solution and is washed out if necessary by water at an organic to aqueous phase ratio equal to 30:1. Iron is re- extracted from the organic phase by interaction with water or acidified water with an organic to aqueous phase ratio equal to 2.5-6.0:1, yielding liquor is a water solution of ferric chloride.

A drawback to this method is utilization of three-component organic mixture in which at least two ingredients (TBP and kerosene) have an enhanced solubility as compared to long chain aliphatic alcohols, therefore the composition of extracting agent will vary during usage. Besides, TBP has a tendency to a hydrolysis and partial polymerization what reduces its extraction properties. According to the patent basic share of extracted iron is due to TBP, therefore it is impossible to receive a high purity solution of ferric chloride because of its unsatisfactory purification of such impurities as: P, Si, Ca, Zn etc. The known method does not allow to receive highly concentrated relative to FeCl₃ liquors for their subsequent high- efficiency processing by spray roasting, the volume of raffmate obtained being practically equal to the volume of the feed solution, what complicates raffmate utilization. When employing as a feed solution the solution with high FeCl₃ concentration (250 kg/m³ and more) and low concentration of impurities (less than 10-15 kg/m³) there would be required a greater ratio of organic and aqueous phases.

A further known method for preparing ferric chloride solution is disclosed in US patent No. 3 497 330. This method comprises providing from iron-containing phosphate rock a feed ferric chloride solution containing, kg/m³: 2.5 of iron ions, 40-80 of hydrochloric acid, 100 of a phosphoric acid and also chlorides of cations of metals, mainly Ca and Mg, present in phosphate rock, and handling so obtained feed solution by means of liquid extraction and re- extraction of ferric chloride. Extraction of ferric chloride is effected by aliphatic alcohols, including isoamyl alcohol, octanol, and hexanol, and also by ketones and esters containing from 5 to 18 carbon atoms at an organic to aqueous phase ratio equal to 0.1-0.2:1.0 to provide an organic phase comprising the most part of ferric chloride and part of phosphoric acid, and an aqueous phase comprising the most part of phosphoric acid and calcium chloride. Organic and aqueous phases are separated to obtain an iron loaded organic solution containing less than 120 kg/m³ FeCl₃, and a raffmate, which is directed to a phosphoric acid extraction. Iron loaded organic is successively stripped and washed to transfer ferric chloride into an aqueous phase part of which is used as stripping agent and is recycled to the feed solution. Regenerated and purified organic phase is returned to the extraction step.

A drawback to this method is that a feed solution contains considerable quantity of calcium chloride which is used as a salting out agent for ferric chloride. However, calcium chloride being an impurity passes into a liquor and is present in the resultant solution of ferric chloride contaminating the latter. Along with calcium chloride the liquor contains substantial quantities of phosphorus. So, phosphoric acid in an amount of 70.0, 44.2 and 47.6 % as calculated for P₂O₅ is co-extracted for isoamyl alcohol, octanol and hexanol accordingly. A known method does not enable to receive highly concentrated in respect of FeCl₃ (300 kg/m³ and more) liquors for their subsequent high performance processing in the installations of spray roasting as far as the solution of ferric chloride is not the main end product.

An object of the present invention is to provide a high-purity concentrated solution of ferric chloride suitable for further processing by spray roasting.

An object of the present invention is also to provide high recovery of ferric chloride (up to from 96 to 98%) irrespective of the nature of impurities present in a feed hydrochloric solution.

An additional object of the invention is to limit volume of waste solutions and optimize material flows and capacity of working equipment.

A still further object of this invention is to restrict the content of any impurity in resulting solution by the order of several mg/1, the concentration of ferric chloride being not less

•a than 300 kg/m , for further processing of the solution in high performance installations of spray roasting which permit to combine in one process receiving of high-purity ferric oxide and regenerated hydrochloric acid of high concentration.

Depending on the nature and content of impurities in a primary chloride solution there are two variants of the present invention realization. The first is preferable in the case when impurities content in a primary chloride solution is less than 2.5 kg/m³ and after concentration step their quantity is insignificant and/or aliphatic alcohols co-extract the impurities to a small extent with consideration for extraction characteristics of the alcohols. Under this embodiment a pure liquor is produced at the first stage of the process.

The second embodiment of the invention is preferable in the case when impurities content in a primary chloride solution is more than 2.5 kg/m³ and after concentration step their quantity is rather great and/or aliphatic alcohols co-extract one or more impurities to a large extent. Under this embodiment a pure liquor is produced at the second stage of the process.

Attainment of the above-mentioned objects with reference to the first embodiment of the invention is provided by a method for preparing ferric chloride solution, which comprises providing a feed hydrochloric acid solution of ferric chloride from a material containing impurities, adding a recycle solution to the feed solution with the formation of a primary hydrochloric acid solution of ferric chloride and processing said solution at a first stage of solvent extraction and stripping steps, the solvent extraction step being performed by aliphatic alcohol as an extracting agent for ferric chloride so as to transfer main portion of ferric chloride into an organic phase, and main portion of impurity chlorides into an aqueous phase, separating said organic phase from said aqueous phase to provide a loaded organic solution and a raffmate, the latter being a source of wastes, and the stripping step is performed by handling said loaded organic solution by a water strip solution with transferring purified ferric chloride into a liquor, and returning spent organic to the extraction step, characterized in that before said extraction step the primary hydrochloric acid solution of ferric chloride is subjected to a concentration step, the method comprises a second stage of concentration, extraction and stripping steps, carried out in the same manner as at the first stage, a first stage raffmate and a main part of the second stage raffmate are combined and directed as a secondary hydrochloric acid solution of ferric chloride to the concentration step of the second stage, a second stage liquor is added as a recycle solution to the feed hydrochloric acid solution and directed to the concentration step of the first stage; concentration steps of the first and second stages are performed by evaporating hydrochloric acid solutions and cooling evaporated solutions to a working temperature, the evaporation being carried out until ferric and impurities chlorides content is below a starting point of salts crystallization in the concentrated and cooled solutions; a resultant condensate containing hydrochloric acid is used as the strip solution at the appropriate stage; purified ferric chloride is withdrawn with the first stage liquor, and the wastes are withdrawn with the second stage raffmate.

Preferably the main and residual parts of the second stage raffmate are in the 3.6-14.2:1 ratio.

Preferably the evaporation of the primary hydro-chloric acid solution is carried out until the ferric and impurity chlorides content is from 650 to 805 kg/m , the first stage extraction step is made in 5 to 6 stages with an organic to aqueous phase ratio equal to 2.9-3.7:1 and residual content of ferric and impurity chlorides in raffmate of 286 to 330 kg/m³, stripping step is performed in 4 to 5 stages, using a condensate from the primary hydrochloric acid solution evaporation as the strip solution, until the ferric chloride content in the liquor solution is from 320 to 400 kg/m³; while the evaporation of the secondary hydrochloric acid solution is carried out until the ferric and impurity chlorides content is from 650 to 792 kg/m³, the second stage extraction step is made in 5 to 6 stages with an organic to aqueous phase ratio equal to 2.8-3.7:1 and residual content of ferric and impurity chlorides in raffmate of 279 to 330 kg/m³, the stripping step being performed in 4 to 5 stages, using condensate from the secondary hydrochloric acid solution evaporation as the strip solution, until ferric and impurity chlorides content in the liquor solution is from 354 to 402 kg/m³.

Preferably also the first stage raffmate is directed in an amount of from 15 to 60% to the evaparation step of the first stage.

Attainment of the mentioned above objects with reference to the second embodiment of the invention is provided by a method for preparing ferric chloride solution, which comprises providing a feed hydrochloric acid solution of ferric chloride from a material containing impurities, adding a recycle solution to the feed solution with the formation of a primary hydrochloric acid solution of ferric chloride and processing said solution at a first stage of solvent extraction and stripping steps, the solvent extraction step being performed by aliphatic alcohol as an extracting agent for ferric chloride so as to transfer main portion of ferric chloride into an organic phase, and main portion of impurity chlorides into an aqueous phase, separating said organic phase from said aqueous phase to provide a loaded organic solution and a raffmate, the latter being a source of wastes, and the stripping step is performed by handling said loaded organic solution by a water strip solution with transferring purified ferric chloride into a liquor, and returning spent organic to the extraction step, characterized in that before said extraction step the primary hydrochloric acid solution of ferric chloride is subjected to a concentration step, the method comprises a second stage of concentration, extraction and stripping steps, carried out in the same manner as at the first stage; a first stage liquor and a residual part of the second stage raffmate are combined and directed as a secondary hydrochloric acid solution of ferric chloride to the concentration step of the second stage, a main part of the first stage raffmate and a main part of the second stage raffmate are added as a recycle solutions to the feed hydrochloric acid solution and directed to the concentration step of the first stage; concentration steps of the first and second stages are performed by evaporating hydrochloric acid solutions and cooling concentrated solutions to a working temperature, the evaporation being carried out until ferric and impurities chlorides content is below a starting point of salts crystallization in concentrated and cooled solutions; a resultant condensate containing hydrochloric acid is used as the strip solution at the appropriate stage; purified ferric chloride is withdrawn with a second stage liquor, and the wastes are withdrawn with a residual part of the first stage raffmate.

Preferably the main and residual parts of the first stage raffmate are in the 4.5-11.3:1 ratio.

Preferably also the main and residual parts of the second stage raffmate are in the 3.0- 3.9:1 ratio.

Preferably the evaporation of the primary hydrochloric acid solution is carried out until the ferric and impurity chlorides content of from 650 to 781 kg/m³, the first stage extraction step is made in 5 to 6 stages with an organic to aqueous phase ratio equal to 2.9-3.6:1 and residual content of ferric and impurity chlorides in raffmate of 280 to 328 kg/m³, stripping step is performed in 4 to 5 stages, using a condensate from the primary hydrochloric acid solution evaporation as the strip solution, until ferric and impurity chlorides content in the liquor solution is from 320 to 400 kg/m³; while the evaporation of the secondary hydrochloric acid solution is carried out until the ferric and impurity chlorides content is from 750 to 821 kg/m³, the second stage extraction step is made in 5 to 6 stages with an organic to aqueous phase ratio equal to 2.8-3.6:1 and residual content of ferric and impurity chlorides in raffmate of 280 to 331 kg/m³, the stripping step being performed in 4 to 5 stages, using a condensate from the secondary hydrochloric acid solution evaporation as the strip solution, until ferric chloride content in the liquor solution is from 350 to 400 kg/m³.

The features which follow reefer to the first as well as the second variants of the invention.

Preferably that the feed hydrochloric acid solution is used containing from 200 to 534 kg/m of ferric chloride and from 30 to 75 kg/m of hydrochloric acid.

Preferably also that the feed hydrochloric acid solution is used containing at least one of the elements Al, Ca, Cu, Cr, Mg, Mn, Na, Ni, P, Si and Zn as an impurity from which ferric chloride is separated, the total content of impurities being from 1.6 to 40.0 kg/m³.

Preferably that at least one of the alcohols: octanol-1, octanol-2, 2-ethyl-gexanol, decanol- 1 is used as an aliphatic alcohol at the first and second stages of the method, the alcohol content being up to 100%). These alcohols have general formula C₈H_2n+ιOH in which n = 6-12.

Preferably as well that the working temperature of the evaporated and cooled solutions at the first and second stages of the method is from 18 to 45°C. Preferably that a condensate from the primary and secondary hydrochloric acid solutions evaporation used as a strip solution contains from 31.5 to 82.5 kg/m³ of hydrochloric acid.

Preferably also at the first and second stages of the method that loaded organic solution after extraction is wash with water containing from 20 to 100 kg/m³, predominantly from 30 to 70 kg/m³, of hydrochloric acid for removal undesirable co-extracted impurities.

A primary solution of ferric chloride is prepared from a feed ferric chloride solution containing impurities with adding to it recycle solutions. According to the first embodiment of the method, a primary solution of ferric chloride is prepared from a feed ferric chloride solution and a second stage liquor to which can be added a part of first stage raffmate. As applied to the second embodiment of the method, a primary solution is prepared from a feed ferric chloride solution containing impurities, a main part of a second stage raffmate and a main part of a first stage raffmate.

Use of the feed hydrochloric solution containing from 200 to 534 kg/m³ of ferric chloride is stipulated by the composition of a feed raw material from which the solution was obtained, processing technology and designation of the end product. Solutions of 200 to 300 kg/m³ FeCl₃ content are usually obtained as a result of ore concentrates leaching by 18-20% hydrochloric acid, as a result of multi-stage extraction of ferric chloride from solutions of complicated composition with respect to impurities and due to processing of industrial wastes. Concentration of from 200 to 300 kg/m³ FeCl₃ corresponds to standard ferric chloride solutions which are usually used on a commercial scale. Ferric chloride content in feed solutions less than 200 kg/m³ makes their processing economically disadvantageous.

Concentrating the primary hydrochloric acid solution of ferric chloride at the first stage of the process allows to raise the content of ferric and impurity chlorides by a factor of 2 to 4. The step is influenced by the peculiarities of extracting agents used, in particular aliphatic alcohols such as octanol-1, octanol-2, 2-ethylgexanol or decanol-1, effective extraction with their use being possible at ferric chloride concentration in a solution of more than 300 kg/m³.

The availability of the second stage of concentrating, extraction and stripping steps with aliphatic alcohols as extracting agents for ferric chloride allows to ensure higher purity of the end product providing simultaneously higher recovery of ferric chloride in an amount of from 96 to 98%). In case of single-stage process the yield does not exceed 70 % at invariably high purity of end ferric chloride solution. Use of the feed hydrochloric acid solution containing from 30 to 75 kg/m³ of free hydrochloric acid is stipulated by the fact that at an acid content less than 30 kg/m³ the solution of ferric chloride is susceptible to hydrolysis while being evaporated with formation of a precipitate. In practice, at small hydrochloric acid content and prolonged boiling such solution is decomposed into HCl and intermediate solid compounds such as Fe(OH)₂Cl and FeOHCl₂. Concentration of hydrochloric acid in a feed solution of more than 75 kg/m³ leads to formation of a condensate with HCl concentration up to 100 kg/m³ and more what makes subsequent stripping difficult.

Use of a feed hydrochloric acid solution containing at least one of the elements Al, Ca, Cu, Cr, Mg, Mn, Na, Ni, P, Si and Zn as an impurity from which ferric chloride is separated with the total content of impurities of 1.6 to 40.0 kg/m³ is stipulated by the following. The quantity of impurities and their composition in primary and secondary chloride solutions depends on the composition of starting raw material from which they are obtained. As a raw material an iron-ore concentrate - magnetite or etching solutions of different origin can be used, in particular, solutions produced as a result of carbon and chromium steels etching etc. Therefore the above-listed raw of impurities is not exhaustive. Apart from the foregoing there may be present in a feed hydrochloric acid solution such impurities as K, Mo, Pb, Ti and so on. The end use of ferric chloride solutions under treatment is also an important factor, in particular, for production of ferrites, magnetic carriers, pigments, storage batteries or using directly for printed circuit cards etching. Overall content of impurities in said solutions can be as high as 40 kg/m and even more. As it was noted earlier it is preferable to treat the primary chloride solution containing less than 2.5 kg/m of impurities according to the first embodiment of the process, and with the content of more than 2.5 kg/m³ using the second variant, the amount of impurities of the order of 40 kg/m being due to from 1 to 3 of the most representative elements.

Concentrating the hydrochloric acid solutions at the first and second stages of the process by way of evaporation is determined by commercial use of the process. Evaporation is effected up to ferric and impurity chlorides concentration that eliminates their crystallization, preferably till from 650 to 820 kg/m³.

Such solutions cooled to a working temperature of 18 to 45°C are chemically stable and in case of sudden apparatus slowdown do not change their state of aggregation for a long period of time. At a temperature less than 18°C crystallization of metal chlorides present in solutions is liable to occur and viscosity growth of organic and water phases is possible what can hamper emulsion stratification during extraction. A temperature of more than 45°C is undesirable due to possible losses of extracting agent as a result of evaporation.

Use as stripping agents of condensates with HCl content of from 31.5 to 82.5 kg/m³ resulting from evaporation of primary and secondary hydrochloric acid solutions is determined by the following. A step of evaporation by itself is rather expensive. In the proposed method a step of ferric chloride stripping at each stage requires a lot of water. If the water be prepared purposely, for example, by ion exchange-distillation method or double distillation procedure then evaporation of such produced water would require a fair quantity of heat, proportional in general to latent heat of condensation - 540 kkal/kg and actually even more. Distillation step, however, takes place by itself when primary and secondary hydrochloric acid solutions are subjected to concentration by evaporation. As a rule, in generated condensates, there is some amount of organic phase, which is added into a feed hydrochloric acid solution along with a recycle solutions. With such condensates for stripping steps it is possible to return into a process some quantity of organic phase thus limiting its losses. The presence of hydrochloric acid in condensates is a favorable factor with regard to ferric chloride stripping. However, at HCl content less than 31.5 kg/m³ there arises a danger of the working solution hydrolysis, especially at the first stage of stripping step. As the quantity of ferric chloride diminishes, and the volume of an aqueous phase accordingly increases, then at reduced solution acidity complete or partial hydrolysis of ferric chloride up to Fe(OH)₂Cl and FeOHCl₂ can take place. At HCl content more than 82.5 kg/m³ a stripping becomes complicated what can lead to growth in number of stripping stages and to slow down the process dew to presence of exorbitant content of acid in an organic phase. In actual practice at HCl content of more than 82.5 kg/m it is possible either to use condensates partially with their previous dilution by water or to reduce an acid content in a primary hydrochloric acid solution.

Use of aliphatic alcohols, mainly octanol-1, octanol-2, 2-ethylgexa-nol, decanol-1 and mixtures thereof, as ferric chloride extracting agent is stipulated by the following. The aliphatic alcohols has a general formula C₈H_2n+ιOH, where n = 6-12. Extraction equilibrium isotherms of said alcohols are mathematically featured by bent in curves. An initial portion of such curve is near an abscissa, what with reference to ferric chloride means practical absence of FeCl₃ extraction into an organic phase at ferric chloride content in an aqueous phase of less than 250 kg/m³. Tangible extraction of FeCl₃ starts at its concentration of 300 kg/m³. Ferric chloride contrary to, for example, ferric sulfate is a well soluble compound. It can be concentrated up to 1000 kg/m³ at increased temperatures. Stability of ferric chloride solution depends on quantity of crystallizing impurities present in it. In practice there can be stable solutions with FeCl₃ concentration of 780 to 850 kg/m³, the lower value concerning greater concentration of impurities.

Aliphatic alcohols are practically insoluble in hydrochloric acid. Use of aliphatic alcohols with alcohol content in organic phase up to 100% allows to utilize mono-product as an extracting agent what is of great importance for preparation of high-purity ferric chloride. In practice it is preferable to use commercial aliphatic alcohols: octanol-1, octanol-2, 2-ethyl- gexanol, decanol-1, which according to acting standards usually contain up to 98% of alcohol.

In case of washing a loaded organic solution at the first and second stages of the process it can be effected by water with adding some portion of a condensate and/or a portion of a liquor, being an end product. Acid concentration in a wash solution can be within from 20 to 100 kg/m limits (preferably from 30 to 70 kg/m ), the solution volume being from 15 to 20 times less than the volume of a loaded organic due to high solubility of ferric chloride in water.

As was told above there are two modifications of the proposed invention depending on the character and content of impurities present in a feed hydrochloric acid solution. Specific features of the first embodiment are as follows.

Guiding a first stage raffmate to the concentration step of the second stage of the process is necessaiy for complete extraction of fenic chloride and removal of the main portion of impurities at the first stage. There is a relationship in this case between content of ferric and impurity chlorides in a feed hydrochloric acid solution and their concentration of 286 to 330 kg/m³ in raffmate that is produced as a result of feed solution processing by aliphatic alcohols as extraction agents.

Recycling a second stage liquor to the concentration step of the first stage of the process is stipulated by the fact that fairly pure liquor forms at the first stage. At the second stage therewith a first stage raffmate evaporation is taking place and additional evaporation of the main part of a second stage raffmate that is artificial concentration of impurities proceeds.

If content and character of impurities in a feed hydrochloric acid solution enable to return a part of the first stage raffmate into the beginning of the process without quality deterioration, then ferric chloride recovery can be increased. Generally, the volume of raffmate recycled portion depends on the quantity of impurities contained in it and their influence upon purity of the liquor, being withdrawn at the first stage as an end product. It is preferable to recycle from 15 to 60% of the first stage raffmate to the concentration step of the first stage. When amount of recycled raffmate is less than 15% ferric chloride recovery drops while its purity rises and on the contrary when amount of added raffmate is more than 60% ferric chloride recovery rises but simultaneously grows an amount of impurities in end product and required capacity of extraction equipment what is undesirable. If extraction step affords effective concentration of increased amount of impurities, then such recycling is rather acceptable.

Concentrating metals chlorides at the first stage of the process till the content of 650 to 805 kg/m³ is stipulated by the following. At concentrations of metals chlorides below prescribed level the process efficiency substantially drops. When pure end product is obtained at the first stage in full volume there is no necessity in the second stage. The problem resides in accomplishing a top FeCl₃ recovery at the first stage. At concentrations of metals chlorides below 650 kg/m³ the recovery falls off to 55-60%. At concentrations higher than 805 kg/m³ a spontaneous crystallization of contained salts will occur during solutions cooling. The most stable operating conditions take place at FeCl₃ concentration of 750 kg/m³.

Carrying out extraction step in 5 to 6 stages at the first stage of the process is due to the following. In the course of extraction using solutions with ferric and impurity chlorides content around 800 kg/m FeCl₃ concentration will be as low as 400 kg/m and less after 3 extraction stages. With two more stages of extraction would successively lowered till 330 and 300 kg/m³. That is growth in number of extraction stages and lowering FeCl₃ concentration lead to a marked drop in certified end product recovery. In other words, growth in number of extraction stages over 6 is commercially unjustifiable, because this leads to growth in amount of equipment used such as pumps, agitators, tanks with appropriate rise of floor area. At stages number less than 5 there appears a danger of underrecovery of base product at the first stage of the process. Naturally, ferric chloride will be recovered additionally at the second stage, but thereafter according to accepted flow sheet it will be recycled along with the liquor to the first stage what would result in material flows increase.

Choice of organic phase to aqueous phase ratio of 2.9-3.7:1 arises from the fact that as organic phase content increases over 3.7:1 value, ferric chloride concentration in organic phase falls. As a result this leads to decrease in ferric chloride concentration in liquor with proper rise in volume of the latter what is undesirable. If organic phase content decreases below 2.9:1 value, ferric chloride concentration in organic phase will substantially (over 170 kg/m ) rise resulting in increased number of extraction stages and undesirable growth of organic phase viscosity.

Residual content of ferric and impurity chlorides in raffmate in amount of 286 to 330 kg/m³ is due to the following. At chlorides concentration below 286 kg/m³ extraction efficiency substantially decreases what makes it necessary to rise (and markedly) a hydrochloric acid concentration. This is yet undesirable from the aforesaid. Fenic and impurity chlorides concentration over 330 kg/m³ leads to undenecovery of fenic chloride at the first stage of the process. This adversely affects on the process effectiveness.

Carrying out a stripping step in 4-5 stages using a condensate from the primary hydrochloric acid solution evaporation as a stripping agent for fenic chloride is caused by the following. A number of stages and a stripping agent consumption are chosen so as to get needed FeCl₃ concentration in a liquor (from 320 to 400 kg/m³) and in a regenerated organic phase (from 10 to 20 kg/m³). Deeper stripping is commercially unjustifiable because of stripping agent consumption increase and considerable dilution of resulting solution what is intolerable for reasons of its subsequent processing. The stripping stages number over 5 is undesirable due to insignificant growth in recovery of resulting product: 10 kg/m³ with 5 stages and 9.5 kg/m³ with 6 stages. At stripping stages number below 4 insufficient FeCl₃ recovery into liquor will take place.

Fenic chloride concentration of 320 to 400 kg/m³ in liquor is due to the following. At concentration below 320 kg/m³ diluted resulting solutions shall be produced what is undesirable since there are certain minimal FeCl₃ and HCl concentrations in the solutions which are directed to spray roasting for production of high-purity ferric oxide and high-concentration hydrochloric acid.

Guiding a first stage raffmate together with a main part of the second stage raffmate to the concentration step of the second stage of the process is stipulated by the fact that pure fenic chloride is produced at the first stage as part of a liquor, while main amount of impurities and about 30% of FeCl₃ remain in raffmate. Therefore a first stage raffmate is guided after extraction to the second stage that is designed for additional recovering of fenic chloride. Combining a first stage raffmate with a main part of the second stage raffmate contributes to maximum fenic chloride recovery. The lack of such second stage raffmate recycle would have resulted in from 90 to 91%) recovery using aliphatic alcohols as extraction agents Returning a main part of the second stage raffmate into a process allows to recover from raffmate some additional amount of fenic chloride, thus affording ultimate recovery of 96 to 98%.

Combining a second stage liquor with a feed hydrochloric acid solution and directing combined solution to the concentration step of the first stage, contributes is determined by the following. In the course of a main part of the second stage raffmate recycling there appear not very favorable conditions for extraction at the stage because of steep rise of impurities. As a result an amount of impurities rises in organic phase and further on in a containing fenic chloride liquor which will not meet the requirements of certified solution. That is why a second stage liquor is combined with a feed hydrochloric acid solution. As far as an amount of impurities per unit weight of FeCl₃ in loaded organic solution is not large after extraction, recycling a second stage liquor to the beginning of the process upgrades feed solution with respect to comparative content of impurities and improves extraction conditions as a whole.

Concentrating metals chlorides at the second stage of the process is effected till their content of 650 to 792 kg/m³ subject to the condition that in the feed solution there are strongly crystallizing impurities such as FeCl₂, CrCl₃, NiCl₂, that is, the impurities which crystallize by themselves even at metals chlorides concentration of 550 kg/m³. At concentration of metals chlorides below 650 kg/m , insufficient FeCl₃ recovery will take place and volume of raffmate part that is directed to the concentration step of the second stage will rise. In this case the said raffmate will contain much more impurities what is undesirable. Upon concentrating till the magnitude of more than 790 to 800 kg/m³, spontaneous crystallization of salts present in evaporated solutions will take place during their cooling down.

Carrying out extraction step in 5 to 6 stages at organic to aqueous phase ratio of 2.8- 3.7:1 is due to the following. Organic phase to aqueous phase ratio both at the first and the second extraction stages of the process depends on degree of end product recovery. If fenic chloride recovery is relatively low, an amount of required organic phase is low too. With organic phase volume increasing over 3.7:1 value, fenic chloride concentration in organic phase lowers. As a result this leads to decrease in fenic chloride concentration in liquor with proper rise in volume of the liquor what is undesirable. If organic phase content decreases below 2.8:1 value, ferric chloride concentration in organic phase will substantially rise (over 180 kg/m ), resulting in increased number of extraction stages and undesirable growth of organic phase viscosity. Residual content of ferric and impurity chlorides in the second stage raffmate in the range of 279 to 330 kg/m³ is due to abrupt fall in fenic chloride transfening into organic phase what complies with extraction equilibrium isotherm. At fenic and impurity chlorides content over 330 kg/m there will be insufficient recovery of end product what is economically disadvantageous.

Carrying out a stripping step in 4 to 5 stages using a second stage condensate as a stripping agent for ferric chloride is caused by the following. According to the first embodiment of the method, solutions produced at the first stage do not contain considerable amount of impurities. While caπying out solution concentrating by means of evaporation, a portion of feed hydrochloric acid solution in dropwise state (spray, condensate and the like) get subsequently into a condensate. If such condensate contains insignificant amount of impurities, it is worthwhile to utilize the condensate as a stripping agent at the first stage of the process. At the second stage solutions are more contaminated by impurities what results in more impure condensates. Excessive condensate formed at the first stage can be used at the second stage. The reverse is yet undesirable because of higher second stage condensate impurity.

Carrying out stripping at the second stage of the process till fenic chloride concentration in liquor of 354 to 402 kg/m³ is due to the following reasons. If solution evaporation at the second stage is effected till fenic and impurities chlorides content of 650 kg/m³ for guaranteed elimination of contained impurities crystallization, then concentration of fenic chlorides and residual impurities in organic phase is lower and chlorides content in liquor will conespondingly be at the lower limit of claimed interval, that is 354 kg/m³. This will not cause any complications since a liquor produced at the second stage is fully recycled to the beginning of the process. Naturally, that more concentrated liquors are more preferable during primary hydrochloric acid solution evaporation at the first stage from energy saving standpoint.

Thus, according to the first embodiment of the method, the following results take place. Guaranteed purity of fenic chloride solution is attained and high recovery of fenic chloride is provided. Along with a raffmate essentially all the impurities are withdrawn, from 2 to 3% of FeCl₃ being lost relative to its initial content. The proposed embodiment of the method is preferable in absence of substantial co-extraction of impurities, which are hard to eliminate without additional washing. Such washings substantially complicate the process and rise it in price with merely partial reduction in impurities content. However, an actual practice shows that there are such co-extracted impurities as chromium, for example, which can be eliminated from an organic phase only together with fenic chloride.

Aforesaid reasoning and arguments are true also for the second of the method. Process peculiarities in this case lie in the following.

Guiding main parts of raffmate produced during extraction steps at the first and the second stages of the process to the concentration step of the first stage is necessary for additional recovery of fenic chloride, otherwise its recovery at the first and the second stages shall be lower than needed. Here the main amount of impurities is withdrawn with residual part of the first stage raffmate as a waste solution of limited volume.

Choice of 4.5-11.3:1 ratio for the main and residual parts of the first stage raffmate is caused by the following. At the ratio value below 4.5:1, that is with decreasing the part of the first stage raffmate directed to the concentration step of the same stage, FeCl₃ recovery will be less than 96%, a purity of ferric chloride solution being somewhat higher. When the ratio is over 11.3:1, a reverse pattern takes place. That is increases the raffmate part directed to the concentration step of the first stage and rises FeCl₃ recovery, a purity of produced ferric chloride solution being somewhat lower.

Guiding a first stage liquor to the concentration step of the second stage of the process results from the fact that insufficiently pure liquor is produced at the first stage. At the second stage therewith a liquor of the first stage and a residual part of the second stage raffmate are subjected to evaporation.

Choice of 3.0-3.9:1 ratio for the main and residual parts of the second stage raffmate is caused by the fact that with the ratio value below 3.0:1 fenic chloride recovery will be below the necessary limit, a purity of fenic chloride at the same time being somewhat higher. At the ratio magnitude over 3.9:1 fenic chloride recovery rises but purity of ferric chloride lowers.

Along with the first stage raffmate a main portion of impurities is withdrawn, about 3.5 to 4%> of FeCl with reference to its initial content being lost. Therefore impurities content in evaporated solution of the second stage is not high and impurities content is substantially lower in loaded organic solution of the second stage and hence in produced liquor than that of the first stage.

Thus, according to the second embodiment of the method co-extraction of unwanted impurities, which contaminate the end product and are hard to eliminate by known practice, takes place at the first stage. Here the first stage liquor, freed from the most part of impurities, along with a residual part of the second stage raffmate acts as a secondary hydrochloric acid solution for repeated concentration. As far as at the output of the second stage of the process there should be produced a fenic chloride of required purity and provided a specified FeCl₃ recovery (not less than 96%), then according to the second embodiment of the method, purified ferric chloride is withdrawn with the second stage liquor, and the wastes - with a residual part of the first stage raffmate. Nevertheless, parameters of concentration, extraction and stripping steps at the first and second stages of the second embodiment of the method are comparable for the most part with the similar parameters of the first embodiment of the method.

In order that the invention may be more readily understood, and so that further features thereof may be appreciated, the both embodiments of the invention will be described below with reference to the accompanying drawings in which:

Figure 1 shows flow sheet of fenic chloride solution production according to the first embodiment of the method;

Figure 2 shows equilibrium isotherm for aliphatic alcohol as extractant for fenic chloride extraction from hydrochloric acid solution with HCl content up to 50 kg/m³, and

Figure 3 shows flow sheet of fenic chloride solution production according to the second embodiment of the method. In compliance with the first embodiment of the invention (see Fig.l), a primary hydrochloric acid solution 1 of ferric chloride is formed by combining a feed fenic chloride solution, produced as a result of acid leaching iron-containing concentrates or chlorinating spent etching solutions, with a liquor 2 of the second stage. The primary ferric chloride solution 1 is directed to the concentration step 3 of the first stage. Concentration is performed by evaporating primary solution 1. A resultant condensate 4 is used as a strip solution 5. A condensate excess 6 is directed to a spray roasting installation. An evaporated solution 7 after cooling (not shown) enters at an extraction step 8 of the first stage of the process where it interacts counter-currently with an extracting agent 9 such as octanol-1, octanol-2, 2-ethylgexanol, decanol-1 or mixtures thereof. Based upon examination of the extraction equilibrium isotherm (see Fig. 2), it is seen that at ferric chloride content in water phase below 250 kg/m³ a FeCl₃ extraction into water phase is practically lacking. Marked FeCl₃ extraction begins as its concentration in solution is about 300 kg/m³. At first stage a FeCl₃ recovery from water phase is no more than 70%. The fact is positive yet from the point of view of limitation of impurities co-extraction into organic phase. Unrecovered fenic chloride acts therewith as a salting out agent for the fenic chloride portion that is being extracted into organic phase. The extraction is carried out in conventional 5 to 6 stages mixer-settlers where the main portion of fenic chloride is extracted into organic phase. A volume of organic phase in the course of extraction decreases, actual decreasing being 10 to 20%. A water phase depleted in fenic chloride - raffmate 10 contains practically all the impurities, while a loaded organic solution or extract 11 comprises most of fenic chloride. A loaded organic solution 11 enters further at a stripping step 12, where as a strip solution use is made of a condensate 5 from the primary solution 1 concentration. Stripping is also effected counter-cunently in multistage mixer-settler where fenic chloride passes from a loaded organic solution 11 into condensate 5 as a water phase. A loaded organic solution 11 loses the most portion of FeCl₃ and, as regenerated extracting agent 9, is recycled to the extraction step 8. A residual content of FeCl₃ in organic phase is from 10 to 20 kg/m³. Fenic chloride stripping by condensate 5 proceeds rather quickly and effectively. Obtained liquor 13 contains essentially fenic chloride with practical absence of impurities and, as an end product, is directed to the spray roasting. Ferric chloride content in liquor 13 is caused by the spray roasting requirements for obtaining regenerated hydrochloric acid of 18 to 19% concentration and high-purity fenic oxide.

Raffmate 10 in full volume is directed to a second stage of concentration, extraction and stripping steps. The stage is used for additional recovery of FeCl₃ from raffmate and for providing minimal volume of waste solutions. Here, raffmate 10 is combined with a main part 14 of the second stage raffinate 15 and directed as a secondary hydrochloric acid solution of fenic chloride to the concentration step 17 of the second stage. As a result of concentration, evaporated solution 18 and acidified condensate 19 are produced. The condensate 19 has a moderate hydrochloric acid concentration and can be effectively used as strip solution 20. A condensate excess 21 is guided to a spray roasted installation. An evaporated solution 18 after cooling (not shown) enters at an extraction step 22 of the second stage of the process, extraction being carried out in the same way as the one at the first stage using the same extracting agent. The resulting loaded organic solution 23 is directed to the extraction step 24 where a condensate 20 from the concentration of the secondary solution 16 is used as a strip solution. The stripping step is effected similar to the one at the first stage. The loaded organic solution 23 loses the most portion of FeCl₃ and, as regenerated extracting agent 25, is recycled to the extraction step 22. As far as impurities content in evaporated solution 18 at the second stage is several times higher than that in evaporated solution 7 at the first stage, then impurities content in a loaded organic solution 23 and in a liquor 2 at the second stage is conespondingly higher than that at the first stage. As a consequence, the liquor 2 is directed as a recycle solution to the beginning of the process and is combined with the feed hydrochloric acid solution.

It is this liquor that contains up to 30% of FeCl₃ which was not recover at the first stage of the process. The second stage raffmate 15 resulting in the course of extraction 22 is divided into two parts. As was aforesaid, the main part 14 of raffinate 15 is combined with the first stage raffmate 10 while a residual part 26 containing essentially all the impurities is withdrawn from the process as liquid wastes.

The volume of raffinate 26, being removed as wastes, is from 2 to 3% of the feed hydrochloric acid solution volume. In other words, if the volume of feed solution is equal to 5 m³ then the volume of waste solution will be 0,10 to 0,15 m³. With regard to insignificant waste solutions volume, it is quite economical to process the solutions by spray roasting thus receiving integrated oxides of impurity elements and regenerated hydrochloric acid what is an advantage of the proposed invention.

Described above flow sheet allows for regulation of FeCl₃ content at the first and second stages by way of recycling a part 27 of raffinate 10 through a valve 28 to the beginning of the process. Such recycle is possible though when there can be attained a specified purity of the liquor 13 as the end product. In this case only a part 10a of raffinate 10 enters a second stage of concentration, extraction and stripping steps.

As was shown above, the second embodiment of the method is preferable in the case when impurities content in the primary chloride solution is increased, for instance, more than 2,5 kg/m or there is one or more impurities, chrome chloride in particular, which are co- extracted along with a ferric chloride and are hard to remove by way of washing or otherwise, what does not allow to get a certified end product. In this case the primary ferric chloride solution 29 (see Fig. 3) is formed by combining a feed hydrochloric acid solution of ferric chloride with a main part 30 of the second stage raffinate 31 and a main part 32 of the first stage raffinate 33. The primary solution 29 is directed to the concentration step 34 of the first stage. Concentration is performed by evaporating primary solution 29. A resultant condensate 35 is used as a strip solution 36. A condensate excess 37 is directed to a spray roasting installation. An evaporated solution 38 after cooling (not shown) enters an extraction step 39 of the first stage of the process where it interacts counter-currently with an extracting agent 40 such as octanol-1, octanol-2, 2-ethylgexanol, decanol-1 or mixtures thereof. An extraction equilibrium isotherm corresponds to the extraction isotherm of the first embodiment of the method (see Fig. 2). Equipment at extraction and stripping steps is the same as for the first embodiment. A water phase depleted in fenic chloride - raffinate 33 contains a great deal of impurities. As was told above, a main part 32 of raffinate 33 is combined with the feed solution for additional recovery of FeCl₃, while a residual part 41 is withdrawn as a waste solution. A fenic chloride loaded organic solution or extract 42 enters further a stripping step 43, where as a strip solution use is made of a condensate 36 from the primary solution 29 evaporation. Fenic chloride passes from a loaded organic solution 42 into a water phase in the form of condensate 36. A loaded organic solution 42 loses the most portion of FeCl₃ and, as a regenerated extracting agent 40, is recycled to the extraction step 39. A residual content of FeCl₃ in organic phase is from 10 to 20 kg/m³. The obtained liquor 44 contains a great deal of FeCl₃ and one or more impurities which content exceeds admissible level. Therefore, the liquor 44 is combined with a residual part 45 of the second stage raffinate 31 and as a secondary hydrochloric acid solution 46 is directed to the concentration step of the second stage of the process.

The stage is used for additional cleaning of fenic chloride solution and additional recovery of FeCl . As a result of concentration 47 an evaporated solution 48 is formed and an acidified condensate 49. The latter is used as a strip solution 50. A condensate excess 51 is guided to a spray roasted insallation. An evaporated solution 48 enters further an extraction step

52, extraction being carried out in the same way as the one at the first stage using the same extracting agent. The resulting loaded organic solution 53 is directed to the stripping step 54 where a condensate 50 is used as a strip solution. The stripping step is effected similar to the one at the first stage. The loaded organic solution 53 loses the most portion of FeCl₃ and, as regenerated extracting agent 55, is recycled to the extraction step 52. As far as impurities content in evaporated solution 48 at the second stage is small, then impurities content in a loaded organic solution 53 and in a liquor 56 at the second stage is conespondingly lower than that at the first stage. Therefore, the liquor 56 is directed to the spray roasting as an end product. This liquor essentially does not contain impurities that are present in the first stage liquor 44. The second stage raffinate 31, resulting in the course of extraction 52, is divided into two parts. The residual part 45 of raffinate 31, as already noted, is combined with the first stage liquor 44, and the main part 30 is recycled at the beginning of the process.

As a result, ferric chloride recovery is from 96 to 98%>. The second stage apparatus is of large-capacity compared to the apparatus of the first stage, since the volume of solutions to be treated at the second stage is well above that at the first stage. The volume of a raffinate 41 withdrawn, as the waste solution, is from 8.0 to 16.0% of the feed solution volume.

Thus, the bases for the first and the second embodiments of the method is the following concept. The first and the second hydrochloric acid solutions are concentrated to the highest extent with respect to fenic and impurity chlorides for providing high efficiency of extraction steps. This allows to extract FeCl₃ into organic phase to the utmost. A volume of waste solution is lowered therewith, especially in the first embodiment of the method. The result of double evaporation resides not only in obtaining concentrated solutions, which are ready for aliphatic alcohols extraction, but producing the liquor with required properties. As a result of the proposed method realization according to the first and the second embodiments, high-quality certified product in the form of fenic chloride solution is obtained, high recovery of fenic chloride is attained and waste solutions of limited volumes are received what is of great importance for commercial use of the method.

The essence and advantages of the proposed method will become more fully apparent from the following examples of specific implementations.

Realization of the invention according to the first embodiment:

Example 1

The example illustrates preparing fenic chloride solution from a feed hydrochloric acid solution of ferric chloride produced as a result of leaching an iron-containing concentrate by hydrochloric acid. The feed solution contains in kg/m³: 243.25 FeCl₃, 75.0 HCl and impurities in g/m³: 308 Al, 53.7 Ca, 1.6 Cu, 1.9 Cr, 34.3 Mn, 170 Na, 1.1 Ni, 9.1 P, 83 Si, 10.9 Zn. The total content of impurity chlorides is in an amount of 1.633 kg/m³. The primary solution of volume 9.819 m is formed by mixing the feed solution of volume 8 m³ and the second stage liquor of volume 1.864 m³. The primary solution contains 270.3 kg/m³ of FeCl₃, 73.71 kg/m³ of

HCl, the total content of impurity chlorides being 1.628 kg/m³. Chemical composition of impurities in the primary solution is the same as in the feed solution. The primary solution is subjected to evaporation whereupon it is cooled to 25°C. The volume of evaporated solution is

3.318 m³. It contains 800 kg/m³ of FeCl₃, 63 kg/m³ of HCl, the total content of impurity chlorides being 4.818 kg/m³ (total content of metal chlorides is 804.818 kg/m³). As an extracting agent a commercial octanol-1 is used with alcohol content of 98%. An extracting agent content is 12.127 m³. The extraction is effected counter-cunently in 6 stages with organic phase to aqueous phase ratio equal to 3.7: 1. This yields a loaded organic solution and a raffinate in an amount of 12.616 kg/m³ and 2.703 kg/m³ correspondingly. The raffinate contains 280 kg/m³ of FeCl₃, 77.32 kg/m³ of HCl, the total content of impurity chlorides being 5.915 kg/m³. Ferric chloride is stripped from the loaded organic by a condensate with HCl content of 76.3 kg/m formed after primary solution evaporation. The stripping is carried out counter-cunently in 5 stages with organic phase to aqueous phase ratio equal to 2.9:1. This yields a regenerated organic phase and a liquor in an amount of 4.743 m³ containing 400 kg/m³ of FeCl₃, 69.03 kg/m of HCl, impurity chlorides are lacking. The first stage liquor contains purified fenic chloride solution as an end product. The regenerated organic phase contains 10 kg/m³ of FeCl₃.

The first stage raffinate of volume 2.703 m³ and the main part of the second stage raffmate of volume 0.869 m³ are subjected to evaporation as a secondary hydrochloric acid solution whereupon the evaporated solution is cooled to 25°C. The volume of evaporated solution is 1.281 m³. It contains 740 kg/m³ of FeCl , 68 kg/m³ of HCl, the total content of impurity chlorides being 52.5 kg/m³. As an extracting agent a commercial octanol-1 is used. An extracting agent content is 4.692 m³. The extraction is effected counter-cunently in 6 stages with organic phase to aqueous phase ratio equal to 3.7:1. This yields a loaded organic solution and a raffinate in an amount of 4,872 kg/m³ and 1.090 kg/m³ correspondingly. The raffinate contains 220 kg/m of FeCl₃, 79.93 kg/m of HCl, the total content of impurity chlorides being 59.11 kg/m³. Ferric chloride is stripped from the loaded organic by a condensate with HCl content of 82.5 kg/m formed after secondary solution evaporation. The stripping is carried out counter-cunently in 5 stages with organic phase to aqueous phase ratio equal to 2.9:1. This yields a regenerated organic phase and a liquor in an amount 1.864 m³ containing 380 kg/m³ of FeCl₃, 75 kg/m³ of HCl, the total content of impurity chlorides being 1.568 kg/m³. The second stage liquor is combined with the feed hydrochloric acid solution. The regenerated organic phase contains 10 kg/m³ of FeCl₃. The second stage residual raffinate of volume 0.221 m³ (the ratio of the main and residual parts of raffinate is 3.9:1) is withdrawn as a waste solution. The waste solution volume is 2.8% of the feed hydrochloric acid solution volume. The fenic chloride recovery into the first stage liquor, as an end product, is 97.5%, FeCl₃ content being 400 kg/m³. The residual content in the product of each impurity element is below sensibility limit of the ICP measuring device.

Example 2

The process is effected according to the provisions of Example 1. The difference resides in another parameters at which the process proceeds. The feed solution contains in kg/m³: 197.6 FeCl₃, 30.0 HCl. The total content of impurity chlorides is in an amount of 2.4 kg/m³. The primary solution of volume 2.908 m³ is formed by mixing the feed solution of volume 2.25 m³ and the second stage liquor of volume 0.6608 m³. The primary solution contains 246 kg/m³ of FeCl₃, 31.39 kg/m³ of HCl, the total content of impurity chlorides being 2.228 kg/m³. Chemical composition of impurities in the primary solution is the same as in the feed solution. The primary solution is subjected to evaporation whereupon it is cooled to 45°C. The volume of evaporated solution is 1.1006 m³. It contains 644.11 kg/m³ of FeCl₃, 63 kg/m³ of HCl, the total content of impurity chlorides being 5.89 kg/m³. As an extracting agent a commercial decanol-1 is used with alcohol content of 98%. An extracting agent content is 3.192 m³. The extraction is effected counter-currently in 5 stages with organic phase to aqueous phase ratio equal to 2.9:1. This yields a loaded organic solution and a raffinate in an amount of 3.304 kg/m³ and 0.9646 kg/m³ correspondingly. The raffinate contains 283.28 kg/m³ of FeCl₃, 77.32 kg/m³ of HCl, the total content of impurity chlorides being 6.718 kg/m³. Ferric chloride is stripped from the loaded organic by a condensate with HCl content of 31.46 kg/m³ formed after primary solution evaporation. The stripping is canied out counter-currently in 4 stages with organic phase to aqueous phase ratio equal to 2.61:1. This yields a regenerated organic phase and a liquor in an amount of 1.362 m³ containing 320 kg/m³ of FeCl₃, 29.24 kg/m³ of HCl, impurity chlorides are lacking. The first stage liquor contains purified fenic chloride solution as an end product. The regenerated organic phase contains 10 kg/m³ of FeCl₃.

The first stage raffinate of volume 0.9646 m³ and the main part of the second stage raffmate of volume 0.614 m are subjected to evaporation as a secondary hydrochloric acid solution whereupon the evaporated solution is cooled to 45°C. The volume of evaporated and cooled solution is 0.742 m³. It contains 538.1 kg/m³ of FeCl₃, 32 kg/m³ of HCl, the total content of impurity chlorides being 111.9 kg/m³. As an extracting agent a commercial decanol-1 is used. An extracting agent content is 2.078 m³. The extraction is effected counter-currently in 5 stages with organic phase to aqueous phase ratio equal to 2.8:1. This yields a loaded organic solution and a raffinate in an amount of 2.146 kg/m³ and 0.657 kg/m³ conespondingly. The raffinate contains 205.3 kg/m³ of FeCl , 36.125 kg/m³ of HCl, the total content of impurity chlorides being 124.7 kg/m³. Fenic chloride is stripped from the loaded organic by a condensate with HCl content of 36.42 kg/m³ formed after secondary solution evaporation. The stripping is carried out counter-currently in 4 stages with organic phase to aqueous phase ratio equal to 3.59:1. This yields a regenerated organic phase and a liquor in an amount 0.661 m³ containing 400 kg/m³ of FeCl₃, 36 kg/m³ of HCl, the total content of impurity chlorides being 1.6344 kg/m³. The second stage liquor is combined with the feed hydrochloric acid solution. The regenerated organic phase contains 10 kg/m³ of FeCl₃. The second stage residual raffinate of volume 0.0433 m³ (the ratio of the main and residual parts of raffinate is 14.2:1) is withdrawn as a waste solution. The waste solution volume is 1.92 % of the feed hydrochloric acid solution volume. The ferric chloride recoveiy into the first stage liquor, as an end product, is 98%>, FeCl₃ content being 320 kg/m . The residual content of each impurity element in the product is below sensibility limit of the ICP measuring device.

Example 3

The process is carried out according to the provisions of Example 1. The difference resides in another parameters at which the process proceeds and in a redistribution of the first stage raffinate. The primary solution of volume 6,86 m³ is formed from the feed solution of volume 5 m³, the second stage liquor of volume 1.033 m³ and a portion of the first stage raffinate of volume 0.829 (40% of the overall volume of the first stage raffinate). The primary solution contains 268.67 kg/m³ of FeCl₃ and 71.59 kg/m³ of HCl. The total content of impurity chlorides is in an amount of 3.048 kg/m . Chemical composition of impurities in the primary solution is the same as in the feed solution. The primary solution is subjected to evaporation whereupon it is cooled to 18°C. The volume of evaporated solution is 2.457 m³. It contains 750 kg/m³ of FeCl₃ and 60 kg/m³ of HCl, the content of impurity chlorides being 8.5 kg/m³ (total content of metal chlorides is 758.508 kg/m³). As an extracting agent a commercial 2-ethyl- gexanol is used with alcohol content of 98%. An extracting agent content is 8.39 m³. The extraction is effected counter-cunently in 5 stages with organic phase to aqueous phase ratio equal to 3.4:1. This yields a loaded organic solution and a raffinate in an amount of 2.072 kg/m³ and 8.694 kg/m³ conespondingly. The raffinate contains 320 kg/m³ of FeCl₃, 71.14 kg/m³ of HCl, the total content of impurity chlorides being 10.09 kg/m³. Fenic chloride is stripped from the loaded organic by a condensate with HCl content of 75.74 kg/m³ formed after primary solution evaporation. The stripping is canied out counter-currently in 4 stages with organic phase to aqueous phase ratio equal to 2.8:1. This yields a regenerated organic phase and a liquor in an amount of 3.371 m³ containing 350 kg/m³ of FeCl₃, 69.72 kg/m³ of HCl, impurity chlorides are lacking. The first stage liquor contains purified fenic chloride solution as an end product. The regenerated organic phase contains 20 kg/m of FeCl₃.

The main part of the first stage raffinate of volume 1.243 m³ and the main part of the second stage raffmate of volume 0.551 m³ are combined and as a secondary hydrochloric acid solution are subjected to evaporation whereupon the evaporated solution is cooled to 18°C. The volume of evaporated and cooled solution is 0.816 m³. It contains 649.5 kg/m³ of FeCl₃, 60 kg/m³ of HCl, the total content of impurity chlorides being 51.64 kg/m³. As an extracting agent a commercial 2-ethylgexanol is used. An extracting agent content is 2.57 m³. The extraction is effected counter-cunently in 5 stages with organic phase to aqueous phase ratio equal to 3.2:1. This yields a loaded organic solution and a raffmate in an amount of 2.663 kg/m³ and 0.703 kg/m³ correspondingly. The raffinate contains 240 kg/m³ of FeCl₃, 69.61 kg/m³ of HCl, the total content of impurity chlorides being 53.71 kg/m³. Fenic chloride is stripped from the loaded organic by a condensate with HCl content of 77.47 kg/m³ formed after secondary solution evaporation. The stripping is carried out counter-cunently in 4 stages with organic phase to aqueous phase ratio equal to 2.8:1. This yields a regenerated organic phase and a liquor in an amount of 1.033 m³, containing 350 kg/m³ of FeCl₃, 65 kg/m³ of HCl, the total content of impurity chlorides being 4.242 kg/m³. The second stage liquor is combined with the feed hydrochloric acid solution. The regenerated organic phase contains 20 kg/m³ of FeCl₃. The second stage residual raffinate of volume 0.152 m³ (the ratio of the main and residual parts of raffinate is 3.6:1) is withdrawn as a waste solution. The waste solution volume is 2.2% of the feed hydrochloric acid solution volume. The fenic chloride recovery into the first stage liquor, as an end product, is 97%, FeCl₃ content being 350 kg/m³. The residual content of each impurity element in the product is below sensibility limit of the ICP measuring device.

Realization of the invention according to the second embodiment:

Example 4

The example illustrates preparing fenic chloride solution from a feed hydrochloric acid solution of fenic chloride produced as a result of spent aching solutions chlorinating. The feed solution contains in kg/m³: 525 FeCl₃, 40 HCl and impurities in g/m³: 111 Al, 153 Ca, 9.3 Cu, 117 Cr, 13.5 Mg, 3106 Mn, 293 Na, 11 Si, 10.8 Zn. The total content of impurity chlorides is in an amount of 9.2877 kg/m . The primary solution of volume 17.857 m is formed by mixing the feed solution of volume 6.5 m , the main part of the first stage raffinate of volume 6.876 m and the main part of the second stage raffinate of volume 4.471 m . The primary solution contains 360.5 kg/m³ of FeCl₃, 44.98 kg/m³ of HCl, the total content of impurity chlorides being 41.922 kg/m³. Chemical composition of impurities in the primary solution is the same as in the feed solution. The primary solution is subjected to evaporation whereupon it is cooled to 28°C. The volume of evaporated solution is 9.196 m³. It contains 700 kg/m³ of FeCl₃, 38 kg/m³ of HCl, the total content of impurity chlorides being 81.404 kg/m³ (total content of metals chlorides is 781.404 kg/m ). As an extracting agent a commercial octanol-2 is used with alcohol content of 98%. An extracting agent content is 32.63 kg/m³. The extraction is effected counter-cunently in 6 stages with organic phase to aqueous phase ratio equal to 3.6:1. This yields a loaded organic solution and a raffinate m an amount of 33.85 kg/m and 7.482 kg/m conespondingly. The raffinate contains 225.36 kg/m³ of FeCl₃, 46.71 kg/m³ of HCl, the total content of impurity chlorides being 99.64 kg/m³. The main and the residual parts of the first stage raffinate are in the 11.3:1 ratio. Fenic chloride is stripped from the loaded organic by the mixture of condensates: a condensate with HCl content of 49.32 kg/m³ formed after primary solution evaporation, a condensate exess with HCl content of 47.37 kg/m³ formed after secondary solution evaporation and specially prepared hydrochloric acid solution with HCl content of 50.61 kg/m³, the actual HCl content in the strip solution being 49.32 kg/m³. Overall volume of extra strip solution added to the first stage condensate is 3.92 m³. The stripping is carried out counter-cunently in 4 stages with organic phase to aqueous phase ratio equal to 2.6:1. This yields a regenerated organic phase and a liquor in an amount of 14.184 m containing 335 kg/m of FeCl₃, 45.64 kg/m³ of HCl, the total content of impurity chlorides being 0.224 kg/m³. The first stage liquor contains excessive amount of impurities and does not comply with the requirements of an end product. The regenerated organic phase contains 10 kg/m³ of FeCl₃.

The first stage liquor of volume 14.184 m³ and the residual part of the second stage raffinate of volume 1.412 m³ are combined and subjected to evaporation as a secondary hydrochloric acid solution whereupon the evaporated solution is cooled to 28°C. The volume of evaporated solution is 6.957 m³. It contains 750 kg/m³ of FeCl₃, 42 kg/m³ of HCl, the total content of impurity chlorides being 0.6 kg/m³. As an extracting agent a commercial octanol-2 is used. An extracting agent content is 22.5 m . The extraction is effected counter-cunently in 5 stages with organic phase to aqueous phase ratio equal to 3.2:1. This yields a loaded organic solution and a raffinate in an amount of 23.34 kg/m³ and 5.88 kg/m³ conespondingly. The raffinate contains 330 kg/m³ of FeCl₃, 49.66 kg/m³ of HCl, the total content of impurity chlorides being 0.71 kg/m³. Fenic chloride is stripped from the loaded organic by a condensate with HCl content of 47.37kg/m³ formed after secondary solution evaporation. The stripping is carried out counter-currently in 5 stages with organic phase to aqueous phase ratio equal to

3.2:1. This yields a regenerated organic phase and a liquor in an amount 8,19 m containing 400 kg/m³ of FeCl₃, 42.86 kg/m³ of HCl. The second stage liquor contains end product in the form of purified fenic chloride. The regenerated organic phase contains 10 kg/m³ of FeCl₃. The main part of the second stage raffinate of volume 4.471 m³ (the ratio of the main and residual parts of raffinate is 3.2:1) is combined with the feed hydrochloric acid solution. The waste solution volume is 9.3%> of the feed solution volume. The fenic chloride recovery into the second stage liquor, as an end product, is 96 %, FeCl₃ content being 400 kg/m . The residual content in the product of each impurity element is below sensibility limit of the ICP measuring device.

Example 5

The Example is similar to the Example 4. The difference resides in another composition of a feed solution and another parameters at which the process steps proceed. The feed solution contains in kg/m³: 280 FeCl₃, 64 HCl and impurities in g/m³: 111 Al, 153 Ca, 9.3 Cu, 117 Cr,

13.5 Mg, 3106 Mn, 293 Na, 11 Si, 10.8 Zn. The total content of impurity chlorides is in an amount of 40 kg/m . The primary solution of volume 6.392 m is formed by mixing the feed solution of volume 3.2 m³, the main part of the first stage raffinate of volume 2.244 m³ and the main part of the second stage raffinate of volume 0.923 m³. The primary solution contains 210.12 kg/m³ of FeCl₃, 62.05 kg/m³ of HCl, the total content of impurity chlorides being 107.34 kg/m³. Chemical composition of impurities in the primary solution is the same as in the feed solution. The primary solution is subjected to evaporation whereupon it is cooled to 30°C. The volume of evaporated solution is 3.127 m³. It contains 430.23 kg/m³ of FeCl₃, 52 kg/m³ of HCl, the total content of impurity chlorides being 219.77 kg/m³ (total content of metals chlorides is 650 kg/m³). As an extracting agent a commercial octanol-1 is used with alcohol content of 98%. An extracting agent content is 9.065 kg/m³. The extraction is effected counter-cunently in 5 stages with organic phase to aqueous phase ratio equal to 2.9:1. This yields a loaded organic solution and a raffinate in an amount of 9.362 kg/m³ and 2.744 kg/m³ conespondingly. The raffmate contains 71.68 kg/m³ of FeCl₃, 59.16 kg/m³ of HCl, the total content of impurity chlorides being 256 kg/m . The main and the residual parts of the first stage raffinate are in the 4.5:1 ratio. Ferric chloride is stripped from the loaded organic by the condensate with HCl content of 69.27 kg/m formed after primary solution evaporation. The stripping is carried out counter-currently in 4 stages with organic phase to aqueous phase ratio equal to 2.8:1. This yields a regenerated organic phase and a liquor in an amount of 3.582 m³ containing 320 kg/m³ of FeCl₃, 64.39 kg/m³ of HCl, the total content of impurity chlorides being 0.317 kg/m³. The first stage liquor contains excessive amount of impurities and does not comply with the requirements of an end product. The regenerated organic phase contains 18 kg/m³ of FeCl₃. The first stage liquor of volume 3.582 m³ and the residual part of the second stage raffinate of volume 0.308 m are combined and subjected to evaporation as a secondary hydrochloric acid solution whereupon the evaporated solution is cooled to 30°C. The volume of evaporated solution is 1.514 m³. It contains 820 kg/m³ of FeCl₃, 52 kg/m³ of HCl, the total content of impurity chlorides being 1 kg/m . As an extracting agent a commercial octanol-1 is used. An extracting agent content is 5.483 m . The extraction is effected counter-cunently in 6 stages with organic phase to aqueous phase ratio equal to 3.6:1. This yields a loaded organic solution and a raffinate in an amount of 5.705 kg/m³ and 1.231 kg/m³ conespondingly. The raffinate contains 310 kg/m³ of FeCl₃, 64 kg/m³ of HCl, the total content of impurity chlorides being 1.23 kg/m³. Fenic chloride is stripped from the loaded organic by a condensate with HCl content of 69.5 kg/m formed after secondary solution evaporation. The stripping is carried out counter-currently in 5 stages with organic phase to aqueous phase ratio equal to 2.9:1. This yields a regenerated organic phase and a liquor in an amount 2.15 m³ containing 400 kg/m³ of FeCl₃, 62.88 kg/m³ of HCl. The second stage liquor contains end product in the form of purified ferric chloride. The regenerated organic phase contains 20 kg/m³ of FeCl₃. The main part of the second stage raffinate of volume 0.923 m³ (the ratio of the main and residual parts of raffinate is 3:1) is combined with the feed hydrochloric acid solution. The waste solution in the form of residual part of the first stage raffinate has the volume of 15.6% of the feed solution volume. The ferric chloride recovery into the second stage liquor, as an end product, is 96 %, FeCl₃ content being 400 kg/m³. The residual content in the product of each impurity element is below sensibility limit of the ICP measuring device.

Example 6

The Example is similar to the Example 4. The difference resides in another composition of a feed solution and another parameters at which the process steps proceed. The feed solution contains in kg/m³: 320 FeCl₃, 50 HCl and impurities in g/m³: 102 Al, 68.3 Ca, 5.7 Cu, 2690 Cr, 71.2 Mn, 1580 Ni, 24.3 Si, 7.8 Zn. The total content of impurity chlorides is in an amount of 12 kg/m³. The primary solution of volume 3.587 m³ is formed by mixing the feed solution of volume 1.75 m³, the main part of the first stage raffinate of volume 1.143 m³ and the main part of the second stage raffinate of volume 0.695 m³. The primary solution contains 253.27 kg/m³ of FeCl and 54.75 kg/m³ of HCl, total amount of impurity chlorides being 52.206 kg/m³. Chemical composition of impurities in the primary solution is the same as in the feed solution. The primary solution is subjected to evaporation whereupon it is cooled to 45°C. The volume of evaporated solution is 1.522 m³. It contains 597 kg/m³ of FeCl₃, 51 kg/m³ of HCl, the total content of impurity chlorides being 123 kg/m (total content of metals chlorides is 720 kg/m ). As an extracting agent a mixture is used of commercial octanol-1 in an amount of 80%> and decanol-1 in an amount of 20%, an alcohol content being 98%. An extracting agent content is 4.413 kg/m³. The extraction is effected counter-cunently in 5 stages with organic phase to aqueous phase ratio equal to 2.9:1. This yields a loaded organic solution and a raffinate in an amount of 4.603 kg/m³ and 1,288 kg/m³ conespondingly. The raffinate contains 135.2 kg/m³ of FeCl₃, 60.26 kg/m³ of HCl, the total content of impurity chlorides being 144.8 kg/m³. The main and the residual parts of the first stage raffinate are in the 7.88:lratio. Fenic chloride is stripped from the loaded organic by the condensate with HCl content of 55.54 kg/m³ formed as a result of primary solution evaporation. The stripping is carried out counter-cunently in 4 stages with organic phase to aqueous phase ratio equal to 2.77:1. This yields a regenerated organic phase and a liquor in an amount of 1.836 m³ containing 400 kg/m³ of FeCl₃, 53 kg/m³ of HCl, the total content of impurity chlorides being 0.3922 kg/m³. The first stage liquor contains excessive amount of impurities and does not comply with the requirements of an end product. The regenerated organic phase contains 15 kg/m of FeCl₃.

The first stage liquor of volume 4.836 m³ and the residual part of the second stage raffinate of volume 0.1782 m³ are combined and subjected to evaporation as a secondary hydrochloric acid solution whereupon the evaporated solution is cooled to 45 C. The volume of evaporated solution is 1.0466 m³. It contains 749.136 kg/m³ of FeCl₃, 48 kg/m³ of HCl, the total content of impurity chlorides being 0.864 kg/m³. As an extracting agent a mixture is used of commercial octanol-1 in an amount of 80%> and decanol-1 in an amount of 20%). An extracting agent content is 2.931 m³. The extraction is effected counter-cunently in 5 stages with organic phase to aqueous phase ratio equal to 2.8:1. This yields a loaded organic solution and a raffinate in an amount of 0.8733 kg/m³ and 1.231 kg/m³ conespondingly. The raffinate contains 278.964 kg/m³ of FeCl₃, 57.53 kg/m³ of HCl, the total content of impurity chlorides being 1.036 kg/m³. Fenic chloride is stripped from the loaded organic by a condensate with HCl content of 56.86 kg/m³ formed as a result of the secondary solution evaporation. The stripping is canied out counter-cunently in 4 stages with organic phase to aqueous phase ratio equal to 2.2:1. This yields a regenerated organic phase and a liquor in an amount 1.544 m containing 350 kg/m of FeCl₃, 52.36 kg/m of HCl. The second stage liquor contains an end product in the form of purified ferric chloride. The regenerated organic phase contains 15 kg/m³ of FeCl₃. The main part of the second stage raffinate of volume 0.695 m³ (the ratio of the main and residual parts of raffmate is 3.9:1) is combined with the feed hydrochloric acid solution. The waste solution in the form of residual part of the first stage raffinate has the volume of 8.29% of the feed solution volume. The fenic chloride recovery into the second stage liquor, as an end product, is 96.5 %, FeCl content being 350 kg/m³. The residual content in the product of each impurity element is below sensibility limit of the ICP measuring device.

Herewith described examples are the mere illustration of proposed embodiments of the invention and particular parameter values of some steps of the method are to be taken as a preferred within the scope of the invention as defined in the claims.

From the above examples it clearly follows that the proposed method enables to produce high-purity fenic chloride solution with not less than 300 kg/m FeCl₃ concentration. Fenic chloride recovery is from 96 to 98% irrespective of the nature of impurities present in a feed hydrochloric solution. The volumes of waste solutions are within the limits of from 2 to 3% and from 8 to 16% of the feed solution volume conespondingly for the first and the second embodiments. The obtained fenic chloride solutions are feasible for further processing in high performance installations of spray roasting with the aim of producing in one process high-purity ferric oxide and regenerated hydrochloric acid of 18 to 19%) concentration. Proposed embodiments of the invention make it possible to optimize material flows and capacity of working equipment. The method according to invention can be effectively used for liquid extraction of other metals, titanium in particular.

Claims

1. A method for preparing ferric chloride solution, which comprises providing a feed hydrochloric acid solution of ferric chloride from a material containing impurities, adding a recycle solution to the feed solution with the formation of a primary hydrochloric acid solution of fenic chloride and processing said solution at a first stage of solvent extraction and stripping steps, the solvent extraction step being performed by aliphatic alcohol as an extracting agent for fenic chloride so as to transfer main portion of ferric chloride into an organic phase, and main portion of impurity chlorides into an aqueous phase, separating said organic phase from said aqueous phase to provide a loaded organic solution and a raffmate, the latter being a source of wastes, and the stripping step is perfonned by handling said loaded organic solution by a water strip solution with transferring purified ferric chloride into a liquor, and returning spent organic to the extraction step, characterized in that before said extraction step the primary hydrochloric acid solution of ferric chloride is subjected to a concentration step, the method comprises a second stage of concentration, extraction and stripping steps, carried out in the same manner as at the first stage, a first stage raffinate and a main part of the second stage raffinate are combined and directed as a secondary hydrochloric acid solution of ferric chloride to the concentration step of the second stage, a second stage liquor is added as a recycle solution to the feed hydrochloric acid solution and directed to the concentration step of the first stage; concentration steps of the first and second stages are performed by evaporating hydrochloric acid solutions and cooling evaporated solutions to a working temperature, the evaporation being canied out until ferric and impurities chlorides content is below a starting point of salts crystallization in the concentrated and cooled solutions; a resultant condensate containing hydrochloric acid is used as the strip solution at the appropriate stage; purified ferric chloride is withdrawn with a first stage liquor, and the wastes are withdrawn with a residual part of the second stage raffinate.

2. The method of claim 1, wherein the main and the residual parts of the second stage raffinate are in the 3.6-14.2:1 ratio.

3. The method of claim 2, wherein the feed hydrochloric acid solution is used containing 200-534 kg/m³ of ferric chloride and 30-75 kg/m³ of hydrochloric acid.

4. The method of claim 3, wherein the feed hydrochloric acid solution is used containing at least one of the elements Al, Ca, Cu, Cr, Mg, Mn, Na, Ni, P, Si and Zn as an impurity from which ferric chloride is separated, the total content of impurities being 1.6-40.0 kg/m³.

5. The method of claim 4, wherein the working temperature of the evaporated and cooled solutions at the first and second stages of the method is 18-45°C.

6. The method of claim 5, wherein at least one of the alcohols octanol-1, octanol-2, 2- ethylgexanol and decanol-1 is used as an aliphatic alcohol at the first and second stages of the method.

7. The method of claim 6, wherein the evaporation of the primary hydro-chloric acid solution is canied out until the fenic and impurity chlorides content is 650-805 kg/m³, the first stage extraction step is made in 5-6 stages with an organic to aqueous phase ratio equal to 2.9- 3.7:1 and residual content of fenic and impurity chlorides in raffmate of 286-330 kg/m³, stripping step is performed in 4-5 stages, using a condensate from the primary hydrochloric acid solution evaporation as the strip solution, until the ferric chloride content in the liquor solution is 320-400 kg/m³; while the evaporation of the secondary hydrochloric acid solution is carried out until the ferric and impurity chlorides content is 650-792 kg/m³, the second stage extraction step is made in 5-6 stages with an organic to aqueous phase ratio equal to 2.8-3.7:1 and residual content of ferric and impurity chlorides in raffinate of 279-330 kg/m³, the stripping step being performed in 4-5 stages, using condensate from the secondary hydrochloric acid solution evaporation as the strip solution, until fenic and impurity chlorides content in the liquor solution is 354-402 kg/m³.

8. The method of claim 7, wherein 15-60 % of the first stage raffinate is directed to the evaporation step of the first stage.

9. The method of claim 8, wherein the condensate from the primary and secondary hydrochloric acid solutions evaporation used as a strip solution contains 31.5-82.5 kg/m³ of hydrochloric acid.

10. A method for preparing ferric chloride solution, which comprises providing a feed hydrochloric acid solution of ferric chloride from a material containing impurities, adding a recycle solution to the feed solution with the formation of a primary hydrochloric acid solution of fenic chloride and processing said solution at a first stage of solvent extraction and stripping steps, the solvent extraction step being perfonned by aliphatic alcohol as an extracting agent for fenic chloride so as to transfer main portion of ferric chloride into an organic phase, and main portion of impurity chlorides into an aqueous phase, separating said organic phase from said aqueous phase to provide a loaded organic solution and a raffinate, the latter being a source of wastes, and the stripping step is performed by handling said loaded organic solution by a water strip solution with transferring purified ferric chloride into a liquor, and returning spent organic to the extraction step, characterized in that before said extraction step the primary hydrochloric acid solution of fenic chloride is subjected to a concentration step, the method comprises a second stage of concentration, extraction and stripping steps, earned out in the same manner as at the first stage; a first stage liquor and a residual part of the second stage raffmate are combined and directed as a secondary hydrochloric acid solution of fenic chloride to the concentration step of the second stage, a main part of the first stage raffinate and a main part of the second stage raffinate are added as a recycle solutions to the feed hydrochloric acid solution and directed to the concentration step of the first stage; concentration steps of the first and second stages are performed by evaporating hydrochloric acid solutions and cooling concentrated solutions to a working temperature, the evaporation being carried out until ferric and impurities chlorides content is below a starting point of salts crystallization in concentrated and cooled solutions; a resultant condensate containing hydrochloric acid is used as the strip solution at the appropriate stage; purified ferric chloride is withdrawn with a second stage liquor, and the wastes are withdrawn with a residual part of the first stage raffinate.

11. The method of claim 10, wherein the main and the residual parts of the first stage raffinate are in the 4.5-11.3:1 ratio.

12. The method of claim 11, wherein the main and the residual parts of the second stage raffinate are in the 3.0-3.9:1 ratio.

13. The method of claim 12, wherein the feed hydrochloric acid solution is used containing 200-534 kg/m³ of fenic chloride and 30-75 kg/m³ of hydrochloric acid.

14. The method of claim 13, wherein the feed hydrochloric acid solution is used containing at least one of the elements Al, Ca, Cu, Cr, Mg, Mn, Na, Ni, P, Si and Zn as an impurity from which fenic chloride is separated, the total content of impurities being 1.6-40.0 kg/m³.

15. The method of claim 14, wherein the working temperature of the evaporated and cooled solutions at the first and second stages of the method is 18-45°C.

16. The method of claim 15, wherein at least one of the alcohols octanol-1, octanol-2, 2- ethylgexanol and decanol-1 is used as an aliphatic alcohol at the first and second stages of the method.

17. The method of claim 16, wherein the evaporation of the primary hydro-chloric acid solution is canied out until the fenic and impurity chlorides content of 650-781 kg/m³, the first stage extraction step is made in 5-6 stages with an organic to aqueous phase ratio equal to 2.9-3.6:1 and residual content of ferric and impurity chlorides in raffinate of 280-328 kg/m³, stripping step is performed in 4-5 stages, using a condensate from the primary hydrochloric acid solution evaporation as the strip solution, until ferric and impurity chlorides content in the liquor solution is 320-400 kg/m³; while the evaporation of the secondary hydrochloric acid solution is canied out until the fenic and impurity chlorides content is 750-821 kg/m³, the second stage extraction step is made in 5-6 stages with an organic to aqueous phase ratio equal to 2.8-3.6:1 and residual content of fenic and impurity chlorides in raffinate of 280-331 kg/m³, the stripping step being perfonned in 4-5 stages, using a condensate from the secondary hydrochloric acid solution evaporation as the strip solution, until fenic chloride content in the liquor solution is 350-400 kg/m³.

18. The method of claim 17, wherein the condensate from the primary and secondary hydrochloric acid solutions evaporation used as a strip solution contains 31.5-82.5 kg/m³ of hydrochloric acid.