US1710522A - Process for concentrating manganese ore - Google Patents

Description

April 23, 1929. H. TRUMBo ET Al. 1,710,522

PROCESS FOR CONCENTRATING MANGANESE ORE Filed Sept. 20, 1927 @wie /Va/gaese are o//a//an wese ,fu/@fe f, INVENTORS i Howard "1T/ambo BY ndrewf Trumbo a Ue WMWWLW ATTORNEYS Patented Apr. 23, 1929.

UNITED STATES PATENT OFFICE.

HOWARD TRUMBO, OF SANTIAGO DE CUBA, CUBA, AND ANDREW J. TR'UMBO, 0F LOS ANGELES, CALIFORNIA, ASSIGNORS T MANGANESE PATENTS CORPORATION, A

CORPORATION 0F NEVADA.

PROCESS FOR CONCENTRATING MANGANESE ORE.

Application led September 20, 1927. Serial No. 220,837.

This invention'relates to a process for concentrating manganese ores and has for its objects the provision of an improved process for treating ores containing manganese in the form of pyrolusite, and ores containing a mixture of pyrolusite and braunite, or a mixture of pyrolusite,.braunite and psilomelane.

In various parts of the world, notably the United States and Cuba, there are considerable amounts of low-grade manganese ores Which are suitable for the manufacture of spiegeleisen but not suitable for the manufacture of ferromanganese Without first being concentrated. Ferromanganese may be used more conveniently than-spiegeleisen and similar alloys containing smaller quantities of manganese in the manufacture of steel, since the required quantity of manganese is contained in a smaller bulk. Consequently, during recent years, the use of spiegeleisen has declined While the use of ferromanganese has increased proportionately, and ,many attempts have been made to develop a process by means of which a product suitable for use in making ferromanganese may be obtained from low-grade ores.

The concentration of various types of lowgrade manganese ores presents many problems. Where possible,`it is generally desirable to' concentrate ores by gravity means alone. However, when the mineral contained in the ore is largely pyrolusite, and is therefore soft and riable, crushing generally produces an excessive amount of lines which are dilicult to recover by gravity or Wet methods of separation. In some of the siliceous manganese ores, the association of the gangue materials With manganese minerals is so intimate that the finest possible grinding Will not permit separation by the. usual mechanical ,A methods.` It is also Well known that an ore Containinghsilica chemically combined With the manganese, or an ore in which the manganiferous particles'are enveloped with colloidal silica cannot be satisfactorily concentrated by the usual Wet or gravity processes.

The particular ore upon which our experiments were conducted and which We are now working profitably on a commercial basis is that which is found abundantly on the island of Cuba, and which contains about 20% to 40% manganese; 1/% to 10% aluminum; 1%

to 12% iron; 5% to 50% silica; 1% to 12% Zircon; and 1% to 12% lime. The ore consists essentially of two manganese minerals, pyrolusite (M1102) and braunite (3Mn2oMnsio3),

intergrown in an intricate manner with several gangue minerals. The ore also contains small quantities of psilomelane (I-I4Mn05). Approximately ninety per cent, or more, of the manganese is in the form of pyrolusite. The most abundant gangue minerals are labradorite, feldspar, and a hydrous aluminum silicate, leverrierite. In addition to these, several other minerals including calcite, kaolin, pyroxene, amphibole, garnet, Zircon and topaz Occur in subordinate amounts.

lThe leverrierite is a soft pink material, gravity 2.6, and it contains minute grains of the manganese minerals. Its unnatural pink color is probably due to the presence of a colloidal manganese compound. Because of the occurrence of considerable manganese in this soft, light Weight, non-magnetic mineral, considerable manganese is lost in the tailingsand slimes When the ore is treated by the usual Wet or gravity processes.

The manganese minerals form some masses of about the size of a pea or slightly larger, but in the majority of instances the manganese minerals act as a matrix to the gangue minerals; or a net-Work of veinlets of manganese minerals project through aggregates of gangue minerals. In a very large proportion of the grains, the included and abundant grains of gangue materials are very small and will average as small as 100 mesh or smaller. For this reason it is diilicult, if not impossible, to obtain a concentrate of pure manganese minerals by the usual Wet or gravity processes of concentration.

As pointed out above deposits of manganese similar to that described above are also found in the United States and various other parts of the World. In many instances the numbers, types, and relative proportions of the minerals making up the gangue vary to some extent, but in most instances the characters of rlhe recovery or separation of the larger particles of pure manganese minerals is a relatively simple matter, but in order to separate the pure manganese minerals from the included gangue minerals in the other particles it is necessary to grind them to a very fine size and the particles of manganese thus produced cannot be satisfactorily segregated from the particles of gangue minerals produced simultaneously by ordinary vet concentration methods, but remain in suspension in the Water .with the gangue minerals. This condition probably results to some extent from the presenc'eof films or coatings of colloidal silica and other substances on the pyrolusite particles which prevent their settling and separation by gravity from the gangue mineral particles. The braunite and psilomelane particles remain suspended in a similar manner. Ore dressing tests have conclusively shown that Where silica is chemically combined ivith manganese or Where colloidal silica envelops the manganiferous particles any of the usual Wet processes or gravity concentration vvill not give the desired result-s.

According to some of the present practices the recovery of manganese from the ore described abo'veby the usual Wet processes or gravity concentration does not exceed fifty percent. rlhe larger particles of pure manganese minerals can be recovered without dificulty by ordinary crushing and jiggng methods, but that portion of the manganese mineral Which is intimately mixed With the gangue minerals cannot be recovered for the reasons pointed out'above.

We have discovered that by subjecting the finely ground or finely divided particles of manganese minerals to the action of a cleaning solution, .such as an aqueous solution of an alkali salt, preferably sodium carbonate or potassium carbonate, the majority ofthe manganese mineral particles become amenable to separation and recovery by gravity methods.

We have also discovered that by recovering the larger particles of pure manganese mmerals by jigging or similar methods, grinding the jig tailings in a rodor ball mill to a suitable size 1n asolution of an alkali `sa1t,`

passing the mill product over suitable tables or similar devices, and leaching the slimes and tailings produced with sulphurdioxide gas in a manner to be later described, We can consistently recover more than ninety percent of the manganese content of the ore in forms suitable for use in dry batteries. for use in the ceramics industry, and for use in the manufacture of ferromanganese and in other. industries.

A complete process for treating manganese ore according to the process of our invention is shovvn in the accompanying How-sheet.

In treating the ore according to the complete process Which We have found to be commercially feasible, the crude ore is first passed over a shaking grizzly, the undersize going directly to a jaw crusher and the oversize being conveyed indirectly by means of a picking belt tothe Crusher. While the ore is on the picking belt the larger pieces of pure manganese mineral and gangue minerals containing little or no manganese values are removed therefrom. The jaws of the Crusher are preferably set to reduce the ore to minus one-half inch in size.

The product from the Crusher is conveyed to revolving trommels -or other suitable screening mediums having one-quarter inch perforations. The undersize from the quarter inch trommels, which is composed substantially entirely of particles between one-eighth and .one-quarter inch in size, is conveyed to a suitable storage bin to await further treatment. The oversizeproduct from the quarter inch trommels is passed through rolls, Which reduce it toY minus one-quarter inch in size,

. and thence through revolvingtrommels having sixteen mesh perforations. The oversize from the sixteen mesh trommels ispassed through trommels having one-eighth inch perforations. The undersize products from the sixteen mesh and one-eighth inch trommels are conducted to a second storage bin to await further treatment. The oversize product from the one-eighth inch trommels is conveyed to the storage bin containing the undersize product from the one-quarter inch trommels. The operations thus far described are conducted for the purpose of crushing and classifying the ore and they are carried out While the ore is in its original dry state. The sizing operations described are considered necessary owing to the fact, .as described above, that most of the larger masses .of pure manganese minerals are of about the size of a pea.

conveyed by suitable feeding means to jigs of any suitable type. As the ore enters the jigs a solution of sodium carbonate containing about five pounds of sodium carbonate per ton of ore to be treated is mixed therevvith. The j igging operations are carried out in the usual manner, sufficient Water being present to aid in coiiducting the solid matter over the jigs in a satisfactory manner. The jig concentrates are conveyed to suitable de- Watering and storage tanks.

The jig tailings are conducted through suitable grinding apparatus, such as a rod mill or ball-mill, Where the particles are reduced to minus twenty-eight mesh. The pulp from the grinding-mill is passed through hydraulic classifiers making six classilications of coarse-products which are conveyed therefrom to suitable concentrating tables.- The liquid from the jig concentrate devvatering tanks containing most of the'slimes produced as'a result of the crushing operations, and the The crushed ore from the storage bins isllO overfiow from the hydraulic classifiers containing most of the slimes produced as a result of the fine grinding operations are conducted to suitable thickeners for the purpose of settling the slimes. The spigot product or thickened slime is passed through a filter for the purpose of relnoving the sodium carbonate solution therefrom, j

The liquid product from the filter and the overflow from the thickener containing the excess sodium carbonate are conducted back and reenter the system with the ore feed to the jigs. The filter cake is passed through a mixing tank Where fresh Water is added inl sufiicient quantity to produce a pulp containing about twenty per cent solids. The sodium carbonate retained in the filter cake causes the slimes to defiocculate readily when fresh water is added to the mixing tank. The pulp thus formed is passed through a series of thickeners, the overflow from which may be Wasted, and the spigot products of which are passed through a suitable hydraulic separator and classifier. The concentratesfrom the separator form a suitable finished product and they may be conducted to a suitable sintering machine. The tailingsl fromthe separator are further subjected to the action of sulphur dioxide gas in a manner Which Will be presently described.

The concentrates from the table concentrating operations described above are dried and cooled and passed through an air separator and cleaner of any .suitable type. The concentrates from the air separator are subjected to the action of a magnetic separator which removes the iron products and then to the a'ction of a second magnetic separator which removes the manganese products, leaving the gangue minerals. l

The pul containing the table tailings is filtered, the filtrate being Wasted and the solid matter being combined in a mixing tank with the gangue from the air separator and cleaner, the gangue containing the iron products, the gangue from the second magnetic separator and the tailings from the hydraulic separator used in the treatment of the slimes. This combined gangue and tailing product is then subjected to the action of sulphurl dioxide gas in the manner outlined for the treatment of copper ores in United States Patent No. 1,312,488. The pulp containing the tailing and gangue products is subjected to the action of a hot mixture of' air and sulphur dioxide gas and the manganese` contained therein, chiefly that in the form of the oxide, is converted to the soluble sulphate form. The iron and aluminum compounds are not affected by the sulphur dioxide.

The pulp containing the manganese sulphate in solution ispassed through suitable classifiers and thickeners in which the gangue is washed to remove the manganese sulphate treated in sintering machines with the fine concentrates, and the sulphur vdioxide gas may berecovered if desired.

The sodium carbonate solution serves as a cleaner for the particles of manganese mineral, and makes it possible to recover by Wet processes or gravity methods of concentration small particles of lnanganese minerals which are ordinarily inseparable from the gangue minerals. Another advantage .of the use of sodium carbonate is that any manganous salts which pass into solution during the concentration process are precipitated and recovered.

lVe have found the sodium carbonate orl other alkali compound used to be effective in increasing the recovery ot manganese minerals in all of the Wet processes or gravity methods of concentration outlined above. For that reason We prefer to add the akali compound to the ore as it goes to the jigs, although satisfactory results may be obtained by adding it `during the fine grinding operations in the rod or ball mills or immediately after the pulp leaves the grinding mills. The cleaning of the mineral particles also aids in removing the iron products and manganese -mineral particles from the .gangue minerals by means of the magnetic separators, and increases the speed and thoroughness of the reaction between the manganese mineral particles and thc sulphurous acid. Whereas, according to some of the present practices, the recovery of manganese minerals from the Cuban ore bythe usual Wet processes or gravity concentration is generally less than fifty percent, we are able to consistently recover more than sixty-five percent by the same processes after first subject-ing the mineral particles to the action of a cleaning solution, and by treating the ore according to our complete process we cau recoverbetween ninety and ninety-five percent of the total manganese values.

While We prefer to use sodium carbonate as a cleaning agent chiefly because of its availability and cheapness, it may be noted that potassium carbonate, sodium bicarbonate, ammonium hydroxide, sodium silicate or the like may be used satisfactorily. l/Vhile we add about five po'unds of sodium carbonate per ton of crude ore before the jigs, the actual consumption, of sodium carbonate is approximately one pound per ton of crude ore, the remainder bein recovered from the ing process, it may be recovered during the sintering operations as pointed out above.

The apparatus used in carrying out the leaching process is similar to that described and illustrated in the United States patent noted above. The balance of the apparatus used is standard equipment.

While We have outlined a process which We have found to be highly satisfactory and which we prefer to use, it is to be understood that certain changes in apparatus, reagents, and order of treatment of the various ore fractions may be made without departingl from the spirit of our invention.

Having now particularly described and ascertained the nature of our said invention, and in What manner the same is to be performed, we declare that whatwe claim is:

1. The process for concentrating manganese ore which comprises subjectinglr the orc to the action of a cleaning solution, and separating the manganese mineral from the gangue by a gravity method of concentration.

2. The process for concentrating manganese ore which comprises grinding the ore, subjecting the mineral particles to the action of a cleaning solution, and separating the manganese mineral particles from the gangue by magnetic means.

3. In a process for treating manganese ore, the step which comprises subjecting the ore to the action of an aqueous solution of an alkali compound.

4. In a process` for. treating manganese ore, the step which comprises subjecting the ore to the action of an aqueous solution of an alkali carbonate. j

5. In a process for treating manganese ore, the step which comprises subjecting the ore to the actiony of an aqueous solution of sodium carbonate.

6. The process for concentrating man-v ganese ore which comprises forming a pulp containing manganese and gangue mineral particles and an aqueous solution of an alkali compound, and t en separatingI the manganese mineral particles from the gangue mineral particles .by a gravity method of concentration.

7 The process for concentrating manganese ore which comprises forming a pulp containing manganese and gangue mineral particles and an aqueous solution of an alkali carbonate, and then separating the nl anganese mineral particles from the gangue mineral particles by a gravity method of concentration.

8. The process for concentrating manganese ore which comprises forming a pulp containing the ore in a finely comminuted state and a solution of sodium carbonate, and then separating the manganese mineral particles from the gangue mineral particles by a gravity method of concentration.-

9. The process for .concentrating manganese ore which comprises grinding the ore, subjecting the mineral particles to the action of a solution of an alkali carbonate, and concentrating the ground ore product by a gravity method of concentration.

1.0. The process for concentrating manganese ore which comprises grinding the ore in the presence of a solutionof sodium carbonate, and concentrating the ground product by a gravity method of concentration.

11. The process for treating manganese ore which comprises grinding the ore, cleaning the mineral particles thereof with a solution of sodium carbonate, and thereafter subjecting said ground product to a gravity process of concentration.

12. The process for concentrating manganese ore which comprises grinding the ore, subjecting the ground product to a wet process of concentration, drying the concentrates produced, subjecting said dried concentrates to the action of an air separator, subjecting the concentrates from said air separator to the action of a magnetic separator to remove iron products therefrom, and subjecting the concentrates from the magnetic separator to the action of a second magnetic separator to remove the manganese mineral particles.

13. The process for concentrating inanganese ore which comprises grinding the ore, concentrating the ground ore byja gravity process, subjecting the concentrates produced to the action of a magnetic separator to remove any iron products contained therein, and subjecting said concentrates to the action of a second magnetic separator to remove the manganese mineral particles there- -from.

In testimony whereof we alix o ur signatures.

- ANDREV J. TRUMBO. V HOWARD TRUMBO.

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