RU2744006C1 - Method of producing tin nitrate (ii) during metal oxidation - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to technology of producing tin (II) salts. Tin nitrate is obtained by oxidising metal with hydrogen peroxide in the presence of a stimulating additive of iodine in a bead mill with a mixer and glass beads in white spirit at room temperature. Glass beads are dosed by weight to the rest without metal weight of 1:1. Beads are loaded into the reactor first, then tin in amount of 10–15 % of the remaining load. Solid phases are washed with aqueous solutions of hydrogen peroxide and nitric acid in amounts calculated with 5–15 % excess to obtain 0.17–0.52 mol/(kg of reaction mixture without metal) of the product. Then, white spirit and iodine are added. Mixture is stirred and the process is carried out until the calculated content of the product in the reaction mixture when checking for accumulation of tin (II) and consumption of hydrogen peroxide and nitric acid. Reaction mixture is separated from the grinding agent and unreacted tin, filtered, the filter cake is washed with a solvent and dried.

EFFECT: reduced requirements for purity of tin up to use of secondary raw materials, elimination of use of inert atmosphere and obtaining of target product in solid form, which is separated by simple filtration.

3 cl, 2 tbl, 11 ex

Description

The invention relates to a technology for producing tin (II) salts and can be used in various fields of chemical and other types of practices, in analytical control and in scientific research.

It is known to obtain tin (II) nitrate during metal oxidation with tin (IV) nitrate in the presence of stimulating additives of iodine and nitric acid (Ageeva L.S., Pozhidaeva S.D., Ivanov AM The use of tin oxidation with tin dioxide and tin (IV) salts at room temperature temperatures in the technology of selective production of tin (II) halides and nitrate Abstracts of the XXVIII Russian Youth Scientific Conference with international participation dedicated to the 100th anniversary of the birth of Professor VA Kuznetsov “Problems of Theoretical and Experimental Chemistry.” Yekaterinburg, 25- April 27, 2018 .-- Yekaterinburg: publishing house Ural, un-ta, 2018 (458 p.) P. 313; Pozhidaeva S.D., Ageeva L.S., Ivanov AM Some features of tin oxidation by tin (IV) compounds in the presence of molecular iodine. Technology of metals. 2018, No. 8, pp. 3-12).

The disadvantages of this method are:

1. It is not issued as a receipt method.

2. It uses tin (IV) nitrate as a metal oxidant, which is not an oxidizing agent widespread in chemical practice, and, therefore, readily available.

The closest to the claimed method is the method of obtaining a solution of tin nitrate (AS USSR No. 356248, publ. 23.10.1972; BI No. 32), according to which amalgated tin is oxidized with copper (II) nitrate at a ratio of gram equivalents of tin in amalgam and copper in a solution of 1.8: 1 and free nitric acid and copper nitrate in a cementitious mortar of at least 1.5: 1 (in mol / l), as well as a ratio of volumes of tin amalgam and a copper solution of at least 2.5: 1.

The disadvantages of this method are:

1. The resulting product is in the form of a rather dilute solution (~ 0.22 mol / kg), which is rather difficult to concentrate, store, and even more so to transport, not to mention the isolation of a solid form.

2. In the process for the formation of tin amalgam, mercury is involved, the work with which requires special conditions in terms of the workplace and the skills of the performer of such work.

3. To carry out the process, an inert atmosphere is required (by the example in the description of -argon), the work in which requires additional operations and has its own specifics.

4. Increased requirements are imposed on the purity of metals, in particular, mercury must be distilled, etc.

5. The given example operates with reagent loading weights up to 10 g. It is not clear whether it can be reproduced with loading weights 10-100 or more times greater.

6. The resulting solution, upon standing, loses the product (becomes cloudy), which is possibly due to the insufficient amount of nitric acid in it to prevent hydrolysis into the basic salt and further into the oxide.

7. In the published description, there is no information on what to do with the spent amalgam and the conversion products of copper nitrate as an oxidizing agent.

The task of the proposed solution is to select such an oxidizing agent and the conditions for the process with the participation of tin as a reducing agent in order to exclude the participation of mercury and other metals (except for tin) in the redox process, to significantly reduce the requirements for the purity of tin up to the use of secondary raw materials, to exclude the use of an inert atmosphere in all operations of the operational scheme and to obtain the target product in solid form, separated by simple filtration, and the process itself is carried out at room and close to it temperatures.

The task is achieved by the fact that tin (II) nitrate is obtained by oxidizing the metal with hydrogen peroxide in the presence of a stimulating iodine addition in a bead mill with a high-speed paddle stirrer and glass beads as a grinding agent in white spirit as a basic solvent at room temperature, glass beads and the rest of the charge without taking into account the mass of the metal is dosed in a mass ratio of 1: 1, the beads are loaded into the reactor first, then fresh and return tin are loaded in total in an amount of 10-15% of the rest of the load and the loaded solid phases in the reactor are washed with 7-15% an aqueous solution of hydrogen peroxide and a 54% aqueous solution of nitric acid with 5-15% stoichiometric excesses calculated to obtain a product in the amount of 0.17-0.52 mol / (kg of the reaction mixture without taking into account the metal), then white is introduced - spirit and a stimulating iodine addition in the amount of 0.05 mol / (kg of the reaction mixture without taking into account the metal), include mechanical stirring and The process is carried out under current control by the method of sampling and determination of tin (II) salt, acid and hydrogen peroxide in them until the calculated value of the product in the final reaction mixture is reached, after which stirring is stopped, the reaction mixture is passed on a filtering unit through a mesh to separate the grinding agent and unreacted metal, after which the resulting suspension-emulsion is filtered, the filter cake is washed with a solvent of the liquid phase and dried, or sent for additional purification; in this case, the aqueous and organic phases of the filtrate are separated and each is subjected to analysis for the content of iodine, iodides, hydrogen peroxide, acid, as well as tin compounds (II) and (IV), after which the organic phase, as well as the washing solvent and unreacted metal, are returned to loading a repeated process; and in the presence of small residual amounts of hydrogen peroxide in the final reaction mixture, the bulk of the introduced stimulating additive is in the form of molecular iodine in the organic phase solution and is removed with it;

Characteristics of the raw materials used:

Metallic tin GOST 860-75.

Nitric acid GOST 4461-77,

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

Molecular iodine GOST 4159-79.

White spirit GOST 3134-78.

Carrying out the process by the claimed method is as follows. Into a vertical bead mill with a glass body and a flat bottom, equipped with a high-speed mechanical stirrer with a wide blade 1-2 mm less than the inner diameter of the body and a height of ~ (0.6-0.7) its width, made like a PCB shaft, load calculated amounts of grinding agent and metal, which are washed with aqueous solutions of hydrogen peroxide and nitric acid in any sequence and using occasional stirring. After that, white spirit and a stimulating iodine addition are introduced, the installation is assembled, it should be fixed in a proper way, the stirrer is manually checked, after which mechanical stirring is turned on, and this moment is taken as the beginning of the process. The calculation of the load is carried out to obtain a certain amount of the product (tin (II) salt) in the reaction mixture with a limited upper limit, which is caused by the ability of the product to oxidize into a tin (IV) salt, the appearance of which in the reaction mixture significantly complicates not only purification, but also the isolation itself. tin (II) salts by filtration.

Oxidation of the metal is carried out with ongoing monitoring of the accumulation of tin (II) salt and occasionally tin (IV) salt, hydrogen peroxide, acid. This mode is predetermined by the unwillingness of a strong decrease in the yield of the target product due to its loss in a large array of samples of the reaction mixture.

As soon as the accumulation of tin (II) salt reaches the declared value, the process is stopped, for which mechanical stirring is stopped, the reactor vessel is disconnected and lowered down in its seat so that the stirrer blade is above the content level. In this position, leave for several minutes to drain the remaining reaction mixture from the shaft and the stirrer blade. After that, the housing is moved from its nest to the filtration unit, where glass beads and unreacted metal are separated from the resulting reaction mixture on a mesh as a filtering partition. The beads and metal are carefully removed from the mesh, returned to the mill housing, the installation is reassembled, a certain amount of white spirit is introduced, and the housing, its elements and solid phases in it are rinsed from the residues of the reaction mixture. Then re-separation of the beads and unreacted metal from the washing solvent is carried out. After drying, beads and metal are separated, weighed and sent to the loading of repeated processes. The washing solvent is collected in a separate container and used in the separation of the reaction mixture.

The previously separated reaction mixture is filtered, the filter cake is treated with a washing solvent and dried, or sent for additional purification, after which an equivalent is made. The filtrate is divided into aqueous and organic phases, which are analyzed for the content of iodine, iodides, hydrogen peroxide, acid, and tin (II) and (IV) nitrates. In this case, in the presence of residual amounts of peroxide in them, almost completely iodide is converted into iodine, which, together with the organic phase, as well as the washing solvent and unreacted metal, is sent to the loading of the repeated process without any additional operations. The aqueous phase is accumulated and used in other directions.

Example # 1

In a vertical bead mill with a plastic body in the form of a glass with an inner diameter of 54.3 mm and a height of 117 mm, a flat bottom and a high-speed stirrer (1560 rpm) and a textolite blade with dimensions of 52 × 36 × 2.5 mm mounted together with a stuffing box in a thick-walled mill cover made of textolite, sequentially load: 100 g of glass beads with a diameter of 1.8-2.5 mm balls and 12 g of fresh tin, 10, 86 g of 9% hydrogen peroxide and 6.13 g 54 % nitric acid. In this case, the loading of aqueous solutions of peroxide and acid is carried out in such a way that the previously introduced beads and metal are well moistened with aqueous solutions, using both occasional shaking and other types of mixing. Next, 81.74 g of white spirit and 1.27 g of molecular iodine are introduced, completing the charge for obtaining 0.25 mol / kg of tin (II) nitrate as the target product. The housing with the loading is placed in the slot of the frame frame, connected to the lid with sockets for sampling, temperature measurement and fractional input of components (if necessary) and rigidly fixed in the designated place. The agitator shaft is turned by hand, mechanical stirring is turned on, and this moment is taken as the beginning of the process. Control is carried out by sampling and determining the content of tin (II) compounds in them (in all samples), hydrogen peroxide (in all even ones), acid (in the third and other odd ones), tin (IV) compounds, acid and peroxide in the latter, in which the content of tin (II) compounds exceeds 0.24 mol / kg. The experiment is continued until all analyzes of the last sample are completed, which in this case takes 10 minutes. After the expiration of their stirring is stopped, turning off the mechanical stirring. The processing of the analysis results is completed and the dependence of the achieved product yield in the time of the process is plotted, given in table. one.

The mill housing is detached from the lid and, together with the contents, is lowered down so that the lower edge of the agitator is above the level of the contents in the housing. Leave in this position for 5 minutes, allowing the reaction mixture (PC) lingering on the housing and stirrer to drain off. Next, the housing with the contents is removed from the nest of the frame frame, transferred to the filtration unit, and the contents are poured into a receiving container with a mesh with a mesh size of 0.2 × 0.2 mm as a filter partition. PC easily falls through such a mesh, leaving a grinding agent and unreacted metal on it. They are carefully removed from the mesh and returned to the housing of the bead mill, which is collected again, 25 g of white spirit is introduced, mechanical stirring is turned on, and the beads, metal, glass housing and other elements are washed from the residues of the reaction mixture for 10 minutes. After the specified time has elapsed, the separation of the grinding agent and unreacted metal is carried out again by collecting the washing solvent in a container intended for this. The metal and beads are separated, dried and weighed. There are no losses of beads, the mass of the reacted tin is 2.97 g. Further, the beads and metal are returned to the loading of repeated processes.

The previously separated PC is filtered, the filter cake is treated with a washing solvent, squeezed out, carefully removed from the filter and dried to constant weight, periodically crushing, and converted into a powdery state. In this case, the mass of the isolated product is 5.55 g, which corresponds to 91.4% of the calculated value. Equivalent to product 243, which corresponds to the gross formula Sn (NO ₃ ) ₂ . This product is stable at room temperature and does not tend to absorb moisture from the air. The resulting filtrate is divided into organic and aqueous phases, which are analyzed for the content of tin (II) and (IV) salts, iodine and iodide, residual acid and peroxide. The washing solvent is analyzed in a similar way. In the organic phase and the washing solvent, the content of these components does not exceed 10 ^-3 mol / kg, with the exception of molecular iodine, which in this case exceeded 10 ^-2 mol / kg. This made it possible to send this phase, as well as the washing solvent, to the loading of the repeated process without subjecting additional operations. The aqueous phase contained an excess of excess amounts of HN ₃ and H ₂ O ₂ , as well as the compounds Sn ²⁺ (~ 10 ^-3 mol / kg) and Sn ⁴⁺ (~ 3310 ^-3 mol / kg). It was drained into a sealable container and left to accumulate from repeated processes.

Examples 2-11.

Reactor, initial reagents, liquid phase solvent, iodine stimulating addition and its dosage, loading weight, sequence of operations when loading PC, carrying out the process, its completion, separating PC from beads and unreacted metal, washing beads, unreacted metal, walls and reactor elements from residues of PC, isolation from the last solid product are similar to those described in example 1. They differ in product concentrations in the final PC, total loading of fresh and return tin, excess nitric acid and hydrogen peroxide, initial concentrations of dosed hydrogen peroxide, use of filtrates and washing solvent in organic phase feeds ... These differences and other characteristics are summarized in table. 2 (PC - reaction mixture).

The positive effect of the proposed solution is:

1. The proposed process is simple both in execution and in the separation of the reaction mixture and the separation of the product from it. It is carried out at or near room temperature and uses available raw materials. There is practically no waste water and components requiring special disposal.

2. In the proposed solutions, a high proportion of the transition of the masses of the initial reagents to the mass of the target product. A by-product is water, which automatically enters the small-volume aqueous phase and is not contaminated, as well as a product requiring disposal.

3. The process is quite simple in hardware and does not require boiler control equipment.

4. The product immediately accumulates in a suspended state and practically does not undergo hydrolysis and does not dissolve in the aqueous component of the bulk phase. This is also hindered by the stabilization of the product due to adsorption processes during its contact with the organic component of the bulk phase dominating in volume.

5. Unreacted metal, washing solvent and organic phase of the filtrate are returned to the loading of repeated processes, thereby not requiring special separation schemes, separation of individual components and utilization as a whole. At the same time, the efficiency factor of the loaded components of the reaction mixture also increases.

6. The proposed solution does not require large excess of nitric acid as a means of suppressing the hydrolysis of the middle salt and the medium for the crystallization of the product. In it, a solid product forms on the metal surface and gets into a suspended state due to mechanical destruction of the layer of surface deposits on the metal.

Claims (3)

1. A method of producing tin (II) nitrate during metal oxidation, characterized in that the metal is oxidized with hydrogen peroxide in the presence of a stimulating iodine addition in a bead mill with a paddle stirrer and glass beads as a grinding agent in white spirit as a base solvent at room temperature , glass beads and the rest of the charge without taking into account the mass of the metal are dosed in a mass ratio of 1: 1, the beads are loaded into the reactor first, then fresh and return tin are loaded in total in an amount of 10-15% of the rest of the load and the loaded solid phases in the reactor are washed 7-15 % aqueous solution of hydrogen peroxide and 54% aqueous solution of nitric acid with 5-15% stoichiometric excess, calculated to obtain a product in the amount of 0.17-0.52 mol / (kg of the reaction mixture excluding metal), then white spirit and a stimulating iodine addition in the amount of 0.05 mol / (kg of the reaction mixture without taking into account the metal) are introduced, mechanical stirring is switched on and the process under current control by the method of sampling and determination of tin (II) salt, acid and hydrogen peroxide in them until the calculated value of the product in the final reaction mixture is reached, after which stirring is stopped, the reaction mixture is passed through a mesh on a filter unit to separate the grinding agent and unreacted metal, after which the resulting suspension-emulsion is filtered, the filter cake is washed with a solvent of the liquid phase and dried, or sent for additional purification. 2. The method according to claim 1, characterized in that the aqueous and organic phases of the filtrate are separated and each subjected to analysis for the content of iodine, iodides, hydrogen peroxide, acid, as well as tin compounds (II) and (IV), after which the organic phase, as well as the washing solvent and unreacted metal are returned to the recycle batch. 3. The method according to claim 1, characterized in that in the presence of residual amounts of hydrogen peroxide in the final reaction mixture, the bulk of the introduced stimulating additive is in the form of molecular iodine in the organic phase solution and is removed with it.

Images