RU2717528C1 - Method of producing tin (ii) chloride by oxidising metal - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention can be used in analytical control and scientific research. Method of producing tin (II) chloride SnCl₂ involves oxidation of tin metal with hydrogen peroxide in the presence of an organic solvent, hydrochloric acid, a stimulating additive of iodine and an additive which stabilizes the product from further oxidation. Organic solvent used is white spirit. Process is carried out in a vertical-type bead mill with a high-speed blade mixer and a glass bead as a grinding agent. Glass beads are dosed in mass ratio 1:1 with the rest of the load without taking into account the metal weight and are loaded into the reactor first. Then, tin is charged in amount of 10–15 % of remaining load. Loaded solid phase is washed with calculated quantities of water solution of hydrogen peroxide and hydrochloric acid solution with stoichiometric excess in terms of obtaining the product in amount of 0.20–0.35 mol/(kg of reaction mixture without taking into account metal). Further, white spirit is added, the additive and iodine stabilizing the product. Mechanical stirring is started. When the specified quantity of the product is achieved, stirring is stopped. Reaction mixture is passed through a screen to separate the grinding agent and unreacted metal. Obtained suspension-emulsion of the reaction mixture is filtered. Precipitate on the filter is washed with a solvent of the liquid phase and dried or directed for additional cleaning.

EFFECT: invention enables to get rid of excess concentrated hydrochloric acid as a medium for suppressing tin (II) chloride hydrolysis, to provide almost complete conversion of the reagent into a product with high selectivity therein.

4 cl, 2 tbl, 10 ex

Description

The invention relates to a method for producing salts of divalent tin and can be used in various fields of chemical practice in industry and in the laboratory, analytical control and scientific research.

A known method of producing tin (II) chloride by chlorination of metallic tin with gaseous chlorine (Author. Certificate. USSR No. 116852, publ. 01.01.1958). In accordance with it, chlorination is carried out at a temperature below the boiling point of SnCl ₂ (230-300 ° C) and an excess of liquid tin, continuously supplied to the reaction zone and ensuring the removal of tin (II) chloride from it. It is noted that this method is simpler in comparison with high-temperature and reduces equipment wear, simplifying the design of the latter and facilitating the selection of materials for its manufacture.

The disadvantages of this method are:

1. High in comparison with the room temperature of the process and the associated design features of hardware design, selection of materials for it and maintenance of the process.

2. Large amounts of tin involved in the process, moreover, in a heated to 230-300 ° C and molten state.

A known method of producing tin (II) chloride by reducing tin (IV) chloride (Author. Certificate of the USSR No. 128007, publ. 1960. BI No. 9), in accordance with which SnCl _{4 is} transferred into an aqueous solution with a concentration of 80-86% and restore metal tin at 100-120 ° C.

The disadvantages of this method are:

1. The proposed method is two-stage: first, chlorination of tin with gaseous chlorine in SnCl ₄ , then the reduction of SnCl ₄ in SnCl ₂ with the appropriate technologies and equipment, as well as the organization of maintaining the temperature regime at each stage.

2. SnCl ₄ as well as SnCl _{2 are} easily hydrolyzable compounds with the formation of basic salts and HCl, which is able to easily react with SnCl ₄ with the formation of H ₂ SnCl ₆ . A highly concentrated solution of SnCl ₄ in water cannot be considered sufficient to prevent the indicated hydrolysis of salts.

3. The process in the second stage requires temperatures of 100-120 ° C, and the allocation of the target product is cooling to 5-10 ° C, which requires the appropriate organization of the supply and removal of heat.

4. There are no balance characteristics, in particular, how much tin (IV) chloride was spent, how much was formed in this product and how much it was allocated. There is no analysis of related products. It is not clear how much product is recovered from the amount obtained in each step.

A known method of preparing a solution of tin (II) chloride by dissolving granular tin in concentrated hydrochloric acid to stop the evolution of hydrogen. The clear liquid is drained from the precipitate, a certain amount of hydrochloric acid is added and diluted with distilled water for a given amount (Rybak BM, Oil product analysis. M .: Goskhimizdat, 1962. -888 p.)

The disadvantages of this method are:

1. The given one-time technique is not framed as a way to obtain neither in terms of balance and time characteristics, nor in terms of hardware design, nor in terms of the characteristics of the resulting product solution.

2. It is not clear what the concentration of excess hydrochloric acid will suppress hydrolysis to such an extent that it can be ignored.

Closest to the claimed is the method (Berl-Lunge. Chemical-technological research methods. - L .: ONTI; L .: Himteoret, 1936), in accordance with which 120 g of granulated tin brand "Bank" is dissolved in 500 ml of hydrochloric acid, with a specific gravity of 1.124 and to stop the evolution of hydrogen (with incomplete dissolution of tin), pour into a 4-liter flask containing 1000 ml of hydrochloric acid with a specific gravity of 1.124 and 2000 ml of water.

The disadvantages of this method are:

1. As in the previous embodiment, the production of tin (II) chloride or its solution is not framed as a production method.

2. The conditions and equipment that ensure the safe evolution of hydrogen from the reaction mixture, which are mandatory for the implementation of this procedure, are not specified.

3. Involved large excesses of concentrated hydrochloric acid.

The objective of the proposed solution is to get rid of the excess of concentrated hydrochloric acid as a medium for suppressing the hydrolysis of tin (II) chloride, to exclude direct interaction of the metal with acid as the main process for the production of tin (II) salt, replacing it with another process of metal oxidation without hydrogen evolution to form the target product, as well as to select such conditions for the process to ensure almost quantitative conversion of the reagent into a product with approaching 100% selectivity for him in the absence of concomitant products requiring the isolation and disposal of products, as well as the relatively simple isolation of the target product in the solid state.

This object is achieved in that the tin (II) chloride is obtained by oxidation of the metal with hydrogen peroxide in the presence of an organic solvent, hydrochloric acid, which stimulates iodine additives and stabilizes the product from further oxidation of the additive in a vertical type bead mill with a high-speed paddle mixer and glass beads as a grinding agent , white spirit is taken as the base solvent, glass beads are dosed in a mass ratio of 1: 1 with the rest of the load, without taking into account the mass of metal and dirt press the first in the reactor, then load tin in the amount of 10-15% of the rest of the load and the loaded solid phase in the reactor is washed with calculated quantities of 7-14% aqueous solutions of hydrogen peroxide and 30-37% hydrochloric acid solution with stoichiometric excesses 5 -20% based on the receipt of the product in an amount of 0.20-0.35 mol / (kg of the reaction mixture excluding metal), then white spirit is introduced, the product stabilizing additive in an amount of 0.5% by weight of the load excluding metal and the addition of iodine in an amount of 0.05 mol / (kg of reaction mixture without metal counting), include mechanical stirring and carry out the process under current control by sampling and determination of tin (II) salt, occasionally acid and hydrogen peroxide in them, and in the last sample and tin (IV) until a specified amount of product is reached, followed by stirring stop, the reaction mixture is passed through a mesh to separate the grinding agent and unreacted metal, then the resulting suspension emulsion of the reaction mixture is filtered, the filter cake is washed with a solvent of a liquid phase and dried, or they are sent for additional purification, while o-aminophenol, hydrochloric acid benzidine, dimethylformamide, thiourea, ethylene glycol, ethyl cellosolve, isopropyl alcohol are used as stabilizing tin (II) salt additives; the aqueous and organic phases of the filtrate are separated and each is analyzed for iodine, iodide, hydrogen peroxide, acid, and tin (II) and (IV) compounds, after which the organic phase, like the unreacted metal, is returned to the batch process and in the presence of small amounts of residual hydrogen peroxide in the final reaction mixture, the bulk of the introduced stimulating additive is in the form of molecular iodine in the solution of the organic phase and returns to the batch process with it.

Characteristics of the raw materials used:

Metal tin GOST 860-75.

Hydrochloric acid GOST 857-95.

Hydrogen peroxide is substandard (according to TU 2123-533-05763441-2011).

Molecular iodine GOST 4159-79.

White Spirit GOST 3134-78.

o-aminophenol GOST 5209-77.

Benzidine GOST 32596-2013.

Dimethylformamide GOST 20289-74.

Thiourea GOST 6344-73.

Ethylene glycol GOST 19710-83.

Ethyl cellosolve GOST 8313-88.

Isopropyl alcohol GOST 9805-84.

The process of the claimed method is as follows. The vertical bead mill with a high-speed (1440 rpm) stirrer with a shaft and a blade made of textolite with a constant location in the frame frame introduces the calculated quantities of glass beads, tin and aqueous solutions of hydrogen peroxide and hydrochloric acid. The introduction of aqueous solutions is carried out in such a way that the solid phases present in the reactor are wetted as best as possible with aqueous solutions. In addition, episodic mixing by shaking and in other ways is also used. Then, during the loading, an organic solvent of the bulk phase is introduced, as well as a stimulating additive of iodine and a stabilizing salt of tin (II) additive. The housing with the loaded contents is placed in the slot of the frame frame intended for it, connected to the lid with the mixer and its stuffing box, properly attached, the mixer shaft is turned and mechanical stirring in the reaction zone is started, which is taken as the beginning of the process. In the course of the latter, samples of the reaction mixture are taken for analysis on the components of the reaction mixture. As soon as the tin (II) salt content reaches the calculated value, the process is stopped and the processing of the reaction mixture is started. To do this, stirring is stopped, the reactor vessel is disconnected from the lid with the blade and lowered so that the remaining reaction mixture from the shaft and the mixer blade can drain. Then, a grinding agent and unreacted metal from the rest of the reaction mixture are separated as a filter baffle in a receiving container for filtering through a mesh. They are returned to the housing again, collected and run the bead mill again, after adding a certain amount of organic solvent. After stirring for a certain time, the washed beads and metal are separated from the washing solvent. The beads and metal are separated, dried and weighed. The loss of mass of the metal is used to assess the real characteristics of the process. Subsequently, both the beads and the metal are sent to the loading of repeated processes.

The separated reaction mixture is filtered. The filter cake is washed with a washing solvent, squeezed out, removed from the filter, weighed and dried in air to constant weight, crushing to a powder state in parallel, after which the product equivalent is determined. The filtrate is divided into organic and aqueous phases, an analysis is made of the components contained in them. The organic phase is directed to the loading of repeated processes, and the aqueous phase is accumulated and used for other purposes.

Example No. 1

In a vertical type bead mill with a glass case in the form of a thick-walled glass with a flat bottom with an inner diameter of 52.9 mm and a height of 125 mm with a high-speed (1440 rpm) paddle-type mixer with a blade made of wear-resistant plastic with dimensions of 50.5 × 37 × 1.9 mm is loaded to obtain 0.23 mol / kg of product 100 g of glass beads, 10 g of a mixture of fresh and returning tin, which are doused with calculated amounts of 10% hydrogen peroxide (9.00 g) and 34% hydrochloric acid ( 5.13 g). For 3 minutes, the introduced beads, metal and solutions are mixed in such a way that the entire surface of the solid phases turns out to be a well-moistened aqueous phase. After that, 84.1 g of white spirit, 0.50 g of the addition of o-aminophenol and 1.27 g of molecular iodine are added. Next, the reactor vessel with the loading is placed in the socket of the frame frame, connected to the lid with the mounted mixer with the stuffing box, properly attached, the mixer shaft is turned by hand, mechanical stirring is turned on, and this moment is taken as the beginning of the process. During the process, without stopping the mechanical stirring, samples of the reaction mixture are taken, which are analyzed for the content of tin (II) salt (all), or tin (II) salt and acid, tin (II) salt and hydrogen peroxide; salts of tin (II) and tin (IV) (in order according to the situation), and the latter on the content of tin (II) and (IV), acid and peroxide. The data obtained are processed in dependence of the time to reach a certain yield of the product, which is presented in table. 1.

Table 1

Product yield,% of calculated 25 50 75 97.5 Time to reach, min 3 26 80 154

Upon reaching a product yield of more than 97.5% of the calculated value, the process of obtaining it is stopped, for which it is enough to stop mechanical stirring in the reactor. The reactor vessel is disconnected from the cover and lowered down in its nest so that the lower edge of the mixer is 3-5 mm higher than the contents of the reactor, allowing residual reaction mixture to drain from the walls of the blade and the shaft of the mixer into the vessel. At the end of this operation, the housing with the contents is removed from the frame frame, transferred to the filtering unit, where the contents are placed in the receiving container of the node with a mesh with mesh sizes of 0.3 × 0.3 mm as a filter partition. The suspension-emulsion of the reaction mixture easily falls through such a grid on which the grinding agent and unreacted metal remain. The latter are removed from the grid, returned to the casing, the bead mill is assembled again, 25 g of white spirit are introduced, mechanical stirring for 10 minutes is included to wash the glass reactor and its elements, grinding agent and unreacted metal from the residues of the reaction mixture. Next, the beads and metal are separated again, dried, the metal is selected manually, weighed. The weight of the beads is 100 g, the unreacted metal is 7.28 g. Subsequently, they are sent to download the second process.

The reaction mixture previously separated from the grinding agent and unreacted metal is filtered, the filter cake is washed with a washing solvent obtained by purification of solid beads and metal from the residual reaction mixture, squeezed out, carefully removed from the filter, dried to constant weight or sent for additional cleaning. In this example, a dry product of 4.00 g is isolated, which is 92% of the theoretical yield.

The obtained filtrate is weighed, separated into organic and aqueous phases, each is weighed and subjected to analysis for the content of tin (II) and (IV) salts, residual acid and peroxide, iodine and iodide. The organic phase, containing the bulk of the introduced iodine and trace amounts of residual components, is returned to the batch processes without any additional treatments. The aqueous phase containing the main quantities of excess and unreacted acid and peroxide is accumulated and used in other directions, including in this process.

Examples 2-10

Reactor, initial reagents, liquid phase solvent, stimulating and stabilizing additives and their quantities, loading mass and metal, sequence of operations when loading the reaction mixture, carrying out the process, its completion, separating the grinding agent and unreacted metal, washing the beads, tin and internal elements of the reactor from the residues of the reaction mixture, the allocation of the last solid product and return the components of the reaction mixture to repeated processes similar to those described in example 1. Differ in concentration the concentrations of the introduced aqueous solutions of the components and their concentrations in the reaction mixture, the concentrations of the product for which the load calculation was made, the nature of the additives stabilizing the product from further oxidation to tin (IV) salt. These differences and other characteristics are summarized in table 2 (RS - reaction mixture).

The positive effect of the proposed solution is:

1. In the proposed solution, a high percentage of the transfer of the mass of the starting reagents to the mass of the target product is achieved. A related product is water, which is not a pollution of the target product, like the environment, and automatically enters the aqueous phase of the reaction mixture, without changing its relative amount much.

2. In the proposed solution, the bulk of the product accumulates in the form of a suspended solid phase, which is easily separated by filtration.

3. The solid phase of the product prevents the formation of crystalline hydrate with water, the hydrolysis of the product into a basic salt, and also helps to stabilize a number of substances that prevent the oxidation of the tin (II) salt into the tin (IV) salt under the chosen conditions.

4. The process is carried out at room temperature and does not require boiler supervision equipment.

5. The process is not complicated by the processing of the liquid phases of the final reaction mixture and the washing solvent. The organic phase, as well as the washing solvent, is returned directly to the loading of repeated processes without any operations, while the small in volume and containing the bulk of excess acid and hydrogen peroxide and trace amounts of tin (II) and (IV) salts are accumulated and used as corrective additives.

6. The process is carried out with a stoichiometric excess of tin, which is separated and without purification from surface deposits is sent to load the second process without any limitation of the ratio of its mass to the mass of fresh metal.

The method of producing tin (II) chloride by metal oxidation Table 2

Characterization of loading and ongoing process Example No. 2 3 4 5 6 7 eight nine ten Download to obtain the product in an amount, mol / kg 0.20 0.28 0.35 0.23 0.23 0.23 0.23 0.23 0.23 Dosage of tin,% of the remaining load 12 fifteen fifteen ten ten ten ten ten ten The concentration of dosed acid,% thirty 34 37 34 34 34 34 34 34 Dosage of HCl, g 5.60 7.21 7.25 5.14 5.14 5.14 5.14 5.14 5.14 Stoichiometric excess of HCl,% fifteen 20 5 eight eight eight eight eight eight The concentration of dosed hydrogen peroxide,% ten 7 fourteen ten ten ten ten ten ten Dosage of hydrogen peroxide solution, g 13.60 14.31 8.98 9.00 9.00 9.00 9.00 9.00 9.00 Stoichiometric excess of H ₂ O ₂ ,% 20 5 eight fifteen fifteen fifteen fifteen fifteen fifteen The nature of the stabilizing additive in an amount of 0.5% of the remaining load excluding metal o-aminophenol o-aminophenol o-aminophenol Hydrochloride benzidine Dimethyl formamide thiourea ethylene glycol ethyl cellosolve Isopropyl alcohol Use in Downloadable Returns: - unreacted tin + + + + + + + + - organic phase of the filtrate + + + - washing solvent + + + Dosage of white spirit, g 79.03 76.71 82.00 84.08 84.09 84.09 84.09 84.09 84.09 Time (min) to achieve product yield,% of theoretical, 25 2 6 12 2 1 1 4 2 5 50 16 61 80 fourteen 12 ten 23 18 20 75 70 118 135 52 33 48 63 40 48 97 and more 133 197 203 132 127 125 147 105 95 The amount of white spirit for washing the reactor, its elements, beads and metal from residues of PC, g 25 thirty thirty 25 25 25 25 25 25 Duration of washing from residues of PC, min eight 12 12 ten ten ten ten ten ten The mass of unreacted metal, g 9.67 11.73 10.93 7.29 7.33 7.31 7.30 7.31 7.34 The mass of the selected dry product, g 3.33 4.85 6.12 4.18 3.97 4.11 4.20 4.03 3.73 The output of the selected dry product,% of the calculated 89.1 92.7 94.0 93.1 92.2 93.7 93.0 90.6 87.7 Equivalent 188 191 189 191 189 190 188

Claims (4)

1. The method of producing tin (II) chloride by metal oxidation, characterized in that the metal is oxidized with hydrogen peroxide in the presence of an organic solvent, hydrochloric acid, stimulating iodine additives and stabilizing the product from further oxidation of the additive in a vertical type bead mill with a high speed paddle mixer and a glass beads as a grinding agent, white spirit is taken as the base solvent, glass beads are dosed in a mass ratio of 1: 1 with the rest of the load without regard to masses s of metal and loaded into the reactor first, then loaded with tin in an amount of 10-15% of the remaining charge and the loaded solid phase in the reactor is washed with calculated amounts of 7-14% aqueous hydrogen peroxide solution and 30-37% hydrochloric acid solution with stoichiometric excesses of 5-20% calculated on the receipt of the product in the amount of 0.20-0.35 mol / (kg of the reaction mixture excluding metal), then white spirit is introduced, the product stabilizing the additive in the amount of 0.5% by weight of the load excluding metal and the addition of iodine in an amount of 0.05 mol / (kg reaction mixtures without taking into account metal), include mechanical stirring and carry out the process under current control by sampling and determination of tin (II) salt, occasionally acid and hydrogen peroxide in them, and in the last sample and tin (IV) until a specified amount of product is reached, after which the stirring is stopped, the reaction mixture is passed through a mesh to separate the grinding agent and unreacted metal, then the resulting suspension emulsion of the reaction mixture is filtered, the filter cake is washed with a solvent of liquid fa PS and dried or sent for additional cleaning. 2. The method according to claim 1, characterized in that the stabilizing salt of tin (II) additives use o-aminophenol, hydrochloride benzidine, dimethylformamide, thiourea, ethylene glycol, ethyl cellosolve, isopropyl alcohol. 3. The method according to claim 1, characterized in that the aqueous and organic phases of the filtrate are separated and each is analyzed for iodine, iodides, hydrogen peroxide, acid, and also tin (II) and (IV) compounds, after which the organic phase, like unreacted metal, they are returned to the batch process again. 4. The method according to claim 1, characterized in that in the presence of small amounts of residual hydrogen peroxide in the final reaction mixture, the bulk of the introduced stimulating additive is in the form of molecular iodine in the solution of the organic phase and returns to the batch process with it.

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