A method of producing manganese dioxide gamma-modification

 

(57) Abstract:

The invention relates to a process of obtaining manganese dioxide gamma-modification and can be used for the manufacture of cathode mass of chemical current sources of manganese-zinc systems. Way to obtain is in the electrolytic synthesis of titanium anodes from solutions of manganese sulfate containing sulfuric acid, with subsequent additional processing of anode sludge in vysokoenergeticheskom grinding apparatus. Mechanochemical activation of the anode sludge are in a planetary mill (50g) for 3 to 10 minutes Additional processing can improve the quality of manganese dioxide and, consequently, to increase the specific energy of chemical current sources in Zn - MnO2the system, based on mechanically activated manganese dioxide, 30% to 60% to 120 WH/kg 2 h.p. f-crystals, 1 table.

The invention relates to a process of obtaining manganese dioxide and can be used for the manufacture of cathode mass of chemical current sources of manganese-zinc systems.

Known methods for producing manganese dioxide by chemical vapor deposition, for example by alkaline treatment of Perma stoichiometry in solution with a concentration of 150-300 g/L. Processing is carried out at 96-102oWith [1]. In the process in addition to these basic components are used nitric acid, potassium lye, potash in large quantities. Mixing of the solutions produced in the fluidized state.

The disadvantage of this method is the formation of the mother liquor, containing all taken an excess of manganese nitrate and potassium nitrate; the mother liquor cannot be used in circulation without releasing nitrate. In addition, the mixing of acidic and alkaline solutions in a fluidized state is a cause of concern due to boiling and splashing.

Known methods for producing manganese dioxide by electrosynthesis in sulfate solutions, for example in solutions with a content of 100-200 g/l manganese sulfate, 20-100 g/l of free sulfuric acid at a temperature of the electrolyte 90-98oC and a current density of 100-300 a/m2[2]. The anode used is a titanium plate. The cathode is made of chrome-Nickel steel.

The disadvantage of this method is the formation of addition-MnO2significant quantities of oxyhydroxide manganese (MnOOH), which is the ballast, as well as education along with the modification of MnO2inactive (manganese-zinc what solution is the way the electrolytic production of manganese dioxide from solutions with a content of ions of bivalent manganese 10-40 g/l free sulfuric acid 100-600 g/L. The electrolysis is carried out at a temperature of 30-50oC and current density And 30-75/DM2. Moreover, to improve the quality of the final product produced by the electrolysis of manganese dioxide is subjected to additional treatment and chemical modification in the electrolyte of the following composition: 400-500 g/l of sulfuric acid, 16-20 g/l Mn2+and 0.3-9.5 g/l Mn3+. The treatment is carried out for 0.5-4 hours at a temperature of 50-100oC to clean the surface and remove oxyhydroxide manganese. Manganese dioxide obtained in this way has a duration of closed circuit when the voltage 1 In 15-20% more than the products obtained by the conventional electrolytic methods [3].

The disadvantages of this method are the duration of the process, additional processing of manganese dioxide, the need to use high concentrations of sulfuric acid, and the high cost of energy to maintain the elevated temperature of the solutions.

The aim of the invention is to improve the quality of manganese dioxide, enabling its use in electrochemical systems. This objective is achieved in that the obtained electrolytic manganese dioxide is subjected to additional mechanochemical treatment during the on update surface there is a partial recrystallization -, - and-MnO2in-shape, which is the most densely Packed crystalline structure is energetically advantageous for high mechanical loads. [4]. Ball load and the lining should be made of inert material (agate, jade, porcelain); contact with metal during grinding almost completely destroys the electrochemical system restore MnO2to Mn2O3.

A specific example of the method.

Electrolytic manganese dioxide (EDM) was obtained by deposition on titanium anodes at a current density of 200 a/m2from the electrolyte containing manganese sulfate 80 g/l and sulfuric acid 10 g/l at a temperature of 95oC. the cathode Material is graphite. Anode precipitate was washed in hot water and detergent solution (10 g/l), and dried. The obtained manganese dioxide was treated in a centrifugal planetary mill M-3 (50g) for 1, 5 and 10 minutes Linkage EDM - 15, Ball download - 500g steel or 100 g of agate grinding phone Drums steel and lined with agate.

From the original and activated powders EDM (weight 2.5 g with the addition of 0.3 g of carbon black) was produced chemical current sources (CCS) in Zn-MnO2the electrochemical system of the second current density jp= 0,02 A/cm2. The discharge was carried out until the voltage of 0.75 Century, the Results of the tests HIT presented in the table. The results of the experiments presented in the table.

As you can see from the test results, the simple grinding, reducing the size of the particles does not lead to any changes in the amount of generated energy (experiments 1 and 2). Mechanochemical processing of electrolytic manganese dioxide in the presence of a reducing agent (metal grinding bodies and the walls of the drums almost completely destroys the electrochemical system of electricity generation tends to zero (experiments 3 and 4). The elimination of the system of reducing agent (lined drums and agate grinding body) allows to obtain a product mainly modifications, practically does not contain other phases, which in turn leads to full actuation of raw materials and increases the production of electricity in chemical current sources Zn-MnO230-60% (experiments 5-7). The increase in the duration of mechanochemical treatment leads to a reduction in this indicator because of overgrinding.

Bibliography

1. A. S. USSR N 78323.

2. A. S. USSR N 655746.

3. A. S. USSR N 470107.

1. A method of producing manganese dioxide-modification electrolytic synthesis of titanium anodes from solutions of manganese sulfate containing sulfuric acid, with subsequent additional processing of anode sludge, characterized in that it further exercise of mechanochemical processing of anode sludge in vysokoenergeticheskom grinding machine.

2. The method according to p. 1, characterized in that the mechanochemical processing of anode sludge is carried out in isolation of the system from the reductant in a lined agate or Jasper, jade, porcelain drums grinding bodies of agate or jade, porcelain.

3. The method according to p. 1 or 2, characterized in that the mechanochemical treatment is carried out in a centrifugal planetary mill.

 

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