DE2460604A1 - PROCESS FOR MANUFACTURING GAMMA-MNO TIEF 2 PRODUCTS OF HIGH QUALITY - Google Patents

Description

Dr.-Jηg. E. BERKENFELD -Dip! .- Iηg. H. PERKENFELD, Patent Attorneys, KoIn Attachment file number

to input · of the name d. Note

Peter Kenneth Everett, 5 Sutherland Street, Neutral Bay, Hew South Wales 2089, : Australia

Process for the production of V ^ -MnO ₉ products of high quality

The invention relates to a method for direct electrical Conversion of low quality manganese ores into high purity manganese dioxide product, which, among other uses i £ eal is suitable for use in dry cells. The procedural conditions are controlled so that impurities in the ore are substantially removed from the product. A decrease the impurity levels over 100 times can be achieved between the product and the supplied ore

The predominant application of the manganese dioxide product is in its use as a cathode depolarizer in the conventional Dry cell battery according to leclanche. This / ^ MnOp higher Quality is ideally suited for dry cell applications because of its high electrochemical activity. Finely Parted Synthetic Dioxide is also used in ferrite manufacture and for pigments. Other areas of application are ceramics, Welding rods and the general chemical industry.

The conventional method for the production of f-MnOp The manganese dioxide ore supplied consists of the following stages:

1) Reduced roasting of the natural MnO ₂ to MnO at high temperature.

2) Dissolution of this MnO in acid in the exhausted electrolyte.

3) cleaning the enriched lye liquids (a) with

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a base to remove iron; and (b) a sulfide to remove heavy metal contaminants.

4) Electrolysis of the filtered electrolyte to produce a MnOp product of high purity at the anode according to equation (2) and hydrogen at the cathode:

2H ⁺ + 2e ~ y H ₂

Notable disadvantages of the conventional process are: a) the need for pretreatment (reducing roasting) of the feed ore which is an energy consuming stage with polluting side effects; b) the development of hydrogen from the hot (80 to 100 ⁰ C) electrolysis cells causes remarkable heat losses due to the greatly increased evaporation of water and can also generate an acid mist, which leads to an unpleasant working environment and building corrosion

2+ leads; c) Exhaustion of the solution Mn content.

The method according to the invention described here essentially relates to the electrorefining of manganese dioxide for production a high quality synthetic product made from natural ore. The main equations describing the reactions at cathode and describe anode are:

Cathode MnO ₂ + 4H ⁺ + 2e ~ .- ^ Mn ²⁺ + 2H ₂ O. (1) Anode JIn ²⁺ + 2H ₂ O- ^ MnO ₂ + 4H ⁺ + 2e "" (2)

Since these equations are related in consumption and formation of the genera only need to replenish the quantities of other materials. This new procedure overcomes at the same time all of the disadvantages of the conventional process and has a remarkably reduced amount of cleaning required because of the selectivity of the lye. Another advantage of this new process is a reduction in the working voltage

2+
in the cell due to the high Mn anolyte concentrations and the lower cathode potential of the dissolution reaction in the

50 98277 087 2

same with the one for Hp development, what a remarkable one Reduction of energy consumption "brings with it.

Since this procedure is based on two reversible equations, the nature of the anode genus is remarkable only to the extent that at which alternating reactions can occur at the electrodes. Hence it must be noted that although sulphate, chloride and fitrate solutions can be used, sulfate solutions are preferred because they present the least labor difficulties.

The method according to the invention can be carried out in a cell which contains three essential elements.

1) a cathode compartment containing a slurry of divided MnO ₂ , the Mn content of which is selectively leached by a reducing environment attributable to the cathode;

2) an anode compartment consisting of a manganese-containing electrolyte (either sulphate, chloride or hitrate) from which a MnOp product is generated;

3) an ion permeable diaphragm which _{is impermeable to the slurry of divided MnO 2} and separates the anode and cathode regions.

Such a typical cell is illustrated in Figure 1, wherein this figure is given to facilitate understanding of the process. It is not to be regarded as a limiting scope of the invention.

The conditions in the anolyte compartment can be controlled so that a number of MnOo products are formed. For example at 90 to 98 0, a “thick anode deposit can occur” of J) ^ - MnOp are deposited, while at 15 to 25 C a divided Product can be formed. Typical materials that are suitable for use on the anode include carbon

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material, lead and titanium, all of which are widely used in industry. The temperature conditions in the catholyte are necessarily similar to those as they are for the educational level of anodic product can be selected. However, markedly different solution conditions can be achieved by controlling the diaphragm material and the electrolysis conditions. The correct selection of the diaphragm material is essential for the control of the anolyte-catholyte acidities, there

2+

the anode reaction is acid producing and Mn i ion is consumed,

while the cathode reaction consumes acid and produces Mn + ion is.

The conditions under which the process according to the invention works are:

i) Anode compartment A temperature of about 15 ⁰ C to the boiling point of the solution (about 120 ⁰ C), with a preferred temperature range of 80 to 100 ⁰ C for the generation of an adherent anode precipitate of Y ^- ^ -MnO ₂ * and from 15 to 25 ⁰ C for a divided product; a solution deficiency content of about 20 g / l Mn to about 200 g / l Mn with a preferred value of 80 to 130 g / l, since this results in a high separation yield

J ^ $ 95 ensures; a working solution acidity from big to about 5n, with a preferred acidity of about 2n; and an anode current density of about 30 to about 250 A / m for an adherent high temperature precipitate and from about 500 to 4000 A / m for a fragmented precipitate. Although high current densities are desirable from a capital investment standpoint, the product properties, current yields and cell operating conditions are superior at medium current densities, so that the preferred current density range is 30 to 120 A / m ² for titanium anodes and 80 to 140 A / m ² for carbon anodes, to get a conventional adherent precipitate. As is known to the person skilled in the art, the high preferred manganese concentrations make it easier to work with high current densities.

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il) Cathode Division The conditions of the cathode solution are related to those in the anolyte by the relative rates of electrolytic generation and consumption and diffusion through the diaphragm. The solution temperatures mentioned are namely 15 ⁰ C up to the boiling point of the solution for the anode; the stated contents of dissolved manganese are 30 g / l to about 220 g / l Mn; the stated degrees of acidity are approximately pH7 to pH0, with a preferred value of approximately pH4 to pH0.5. Indeed, low catholyte acidities are particularly important to avoid dissolution of non-manganese elements.

A pesticide load of about 20 to 350 g / l can be used, with the preferred range being about 50 to 200 g / l. The ore fed should preferably be finely ground, for example less than 50 / km, in order to achieve a high degree of dissolution efficiency, but the process can also be carried out with larger particle sizes. Along with catholyte acidity, the selection of the cathode material and the current density are particularly important in order _{to control the selective leaching of MnO 2} and to prevent the dissolution of impurities. Typical cathode current densities of 5 to 400 A / m can be used, with current densities of 25 to 100 A / m being preferred.

example

The following exemplary embodiment is provided for illustration purposes only of the method according to the invention and should be beyond the scope make no statement about the invention.

g of MnO ₂ ore are moved in 81 MnSO, solution (105 g / 1 Mn ²⁺ and 2.9 g / 1 H ₂ SO,) in a diaphragm cell which contains three titanium anodes, each with a submerged area of cm χ 10 cm and enclosed in diaphragm pockets made of polypropylene cloth, and four graphite cathodes, with an immersed area of 12 cm 10 cm each, outside the diaphragm pockets.

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current - 6 - is 2.1 volts. Of the table below is formed - ore supplied 2460604 apparent that product Electrolyte residue Beginning end 8 6 It will sent through with high purity Contamination level, and p.
60A / m anode area namely and a great reduction in the 2.9 g / l anolyte. Catholyte > 14 14 For 96 hours at one temperature can between $ 45 from 90 ⁰ G. The middle one although 100 times in the case of Fe, - 98.0g / l 9.8g / l 78 · 70 Cell voltage MnOp product is made by 20th Energy consumption and product can be achieved. $ 9.5 $ 9.3 130 110 1.24 KWI Catholyte slurry ever Table I: Analytical Results $ 20 Tle. 190mg / l 320mg / l 114 100 IAg. Residue. Component ore 150 stripped of the titanium anodes product .35 000 . per million 2 4 The adherent From the 100 is filtered to obtain the 250 - - and the H ₂ SO ₄ 70 - 200 100 400 100 I is 100 240 600 Mn 70 $ 62 200 40 120 Fe 60 000 TIe. "200 Tie 100 40 200 440 Mill. - per Mill 100 Gu 16 20th 1,000 ■ - «.-. - - Pb 10 50 30,000 Zn 5 20th 25,000 Ή1 1 20th 12,000 Go 30th 2,300 Size 1 10 Mon - 560 Ga 000 200 Mg 000 K 500 200 Ka 040 20 number Gram 200 675

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. "■ - ■ ~~ -" ~ --7 "-" ~ '"■ T46Ö6Q4

From Table II it can be seen that a product of high electrochemical Activity can be established. The product produced was made with a standardized electrolytic manganese dioxide compared by Japan. The determination of the electrochemical Activity method used is the grain file test. A manganese dioxide sample (0.5Og) and acetylene black (0.20g) are available as Slurry with the electrolyte solution (solution Kornfeil 2) mixed with a standardized moisture content. This mixture is then placed in the grain filing cell and the wet black mixture compressed with the carbon cathode rod by pressing with a 2kg weight loaded. The resulting grain file pellet is held under this load and discharged between the coal and zinc electrodes with constant current draws. The remaining cell voltage is determined as a puncture after a Pulse interruption technique up to a final voltage of 1.00 volts. The discharge time is used as a measure of the electrochemical Activity of manganese dioxide taken.

Table II: Electrochemical activity of the product

Product time up to 1.0 YoIt time up to 1.0 volts

with high current - with low current draw of 60 mA, a subtraction of 12 mA

Standardized electrolytic 4th 000 see. 25th 200 see. MnO ₂ (Japan) Product of the example 4th 300 27 000

While the invention relates to a process for the electrorefining of MnOp, it is to be noted that there are many Schematic work plans are possible, of which the following illustrations are only given as examples.

The following discussion has been limited to the formation of adherent / jf-MnOg at high temperature (80-10O ⁰ C) for illustrative purposes only.

The simplest schematic work plan (Pig.2) is to add it ground ore to an electrolytic cell, weΙ49 / 1 509827/0872

before contains a prepared electrolyte and that to some extent or half-batch dissolving of the ore takes place. When electrolysis is due to ore depletion or slurry accumulation has stopped, the manganese-poor residue is separated from the solution and the solution is returned to the cell and the Procedure repeated. The anode can be removed periodically and the adhering precipitate at any time throughout rudimentary dissolution be stripped off. Modifications to the above including continuous ore addition to one non-flowing cell or to a continuous flow system over a multiple series of cells are obvious to those skilled in the art.

One aspect of the above single cell is the continuous one Removal of part of the catholyte and the return of the solution after filtering to the cell, for example to the anolyte (Fig. 3). If desired, one can do some kind of cleaning treatment, such as pH adjustment, before the electrolyte is returned to the cell.

Claims

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Claims (16)

Dr.-1 ng. E. BERKENFELD ^ Dipl.-ing. H. EERK5NFELD, patent attorneys, Cologne Annex · '......: file IDs for input «from the name of the. Note Peter Kenneth Everett,. ; ■ 5 Sutherland Street, Neutral Bay,. f.: '. 'New South Wales 2089,' Australia Claims 1. Process for making high quality J ^ -MnOp products by electrorefining a manganese dioxide ore in a diaphragm cell, characterized by the controlled cathodic reduction of an ore slurry in an aqueous one Electrolytes. 2 _.: Process according to claim 1, characterized in that an electrolyte is used which has the sulfate anion group. 3. The method according to claim 1, characterized in that one uses an electrolyte which has the anion group ChlorId. 4. The method according to claim 1, characterized in that one an electrolyte is used which has the anion group nitrate. 5. The method according to claim 1 "to 4, characterized in that e:
holds. a cell temperature of 15 ⁰ G up to the boiling point 6. The method according to claim 5> characterized in that a cell temperature of 80 "to 100 ⁰ C is maintained. 7. The method according to claim 1 to 6, characterized in that the product is formed as an anodic deposit and an anodic current density of about 20 to about 250 A / m is maintained. ^{E 49/1} 509827/0872 8. The method according to claim 7, 'characterized in that one maintains a current density of about 30 to 140 A / m. 9. The method according to claim 1 to 6, characterized in that the product is formed as a divided slurry and an anodic current density of about 1000 to 4000 A / m at about 15 to 25 C is maintained. 10. The method according to claim 1 to 9 »characterized in that an anolyte is used which contains about 20 to 200 g / l Mn and up to 5 η acid. 11. The method according to claim 10, characterized in that an anolyte is used which contains about 80 to 130 g / l Mn and contains about 2 η acid. 12. The method according to any one of the preceding claims, characterized characterized in that one has a cathodic current density of 5 to 400 A / m ² . 13. The method according to claim 12, characterized in that one maintains a cathodic current density of 25 to 100 A / m. 14. The method according to any one of the preceding claims, characterized characterized in that a catholyte is used, the ore content of which is about 20 to 350 g / l. 15. The method according to claim 14, characterized in that a catholyte is used, the ore content of which is about 50 to 200 g / l. 16. The method according to any one of the preceding claims, characterized characterized in that one uses a catholyte which contains about 30 to 220 g / l of dissolved Mn and one Has acidity from pH7 to about pHO. 509827/0872 ~ '- "246Ö6Ö4 17 »The method according to claim 16, characterized in that an Eatholyte is used, the acid content of which is such that the pH is in the range from about pH4 to pH0.5. 49/1 509827/0872 Blank page