WO1980000131A1

WO1980000131A1 - Magnetic separation process for beneficiating sulfide ores

Info

Publication number: WO1980000131A1
Application number: PCT/US1979/000475
Authority: WO
Inventors: J Kindig; R Turner
Original assignee: Hazen Research
Priority date: 1978-07-03
Filing date: 1979-07-02
Publication date: 1980-02-07
Also published as: GB2039870A; AU531300B2; AU4860379A; GB2039870B

Abstract

A process for beneficiating one or more mineral values of sulfide and oxide ores by treating the ore with a metal-containing compound under conditions such as to selectively enhance the magnetic susceptibility of the mineral values to the exclusion of the gangue in order to permit a separation between the values and gangue, and improvements comprising: pretreating the ore by heating it to a temperature of at least about 80 C for at least about 0.1 hours; removing any elemental sulfur present in the ore by preheating or solvent extraction prior to treating the ore with the metal-containing compound; cotreating the ore with a reducing gas while preheating, or while treating with the metal-containing compound.

Description

Magnetic Separation Process For Beneficiating Sulfide Ores

Technical Field

This invention relates to improved means for treating ores to separate the mineral value from gangue material by selectively enhancing the magnetic susceptibility of the mineral values so that they may be separated from the gangue.

Background Art As is well known, mining operations in the past for recovering various metals, (e.g., lead and copper), have utilized high grade ore deposits where possible. Many of these deposits have been exhausted and mining of lower grade ores is increasing. The processing of these leaner ores consumes large amounts of time, labor, reagents, power and water with conventional processing.

In addition to the increased expense associated with the extraction of these metals from low grade ores, proposed processes for separation of certain of the ores are technically very difficult and involve elaborate and expensive equipment. In many cases the expense incurred by such separation would be greater than the commercial value of the metal, such that the mineral recovery, while theoretically possible, is economically unfeasible. Our U.S. Patent No. 3,938,966, issued February 17, 1976 for "Process for Improving Coal", by Kindig and Turner, discloses treating raw coal with undecomposed iron carbonyl to alter the magnetic susceptibility of certain impurity components contained in the raw coal, thereby permitting their removal by low intensity magnetic separators.

This patent is concerned only with coal and not with the treatment of the sulfide and oxide ores of the present invention, nor does it disclose the pretreatment and co-treatment improvements of the present invention.

Disclosure of Invention The process of the present invention entails treating a sulfide ore or a metal oxide ore selected from the group consisting of bauxite, taconite, apatite, titanium silicates and the metal oxides of Groups IIIB, IVB, VB, VIB, VIIB, VIIIB, IB, IIB and IVA with a metal containing compound under processing conditions such that the magnetic susceptibility of the ore is selectively enhanced to the exclusion of the gangue. The affected ore values may then be magnetically separated from the less magnetic constituents.

The ore may be further beneficiated by pretreating the ore to remove at least a portion of any elemental sulfur present prior to treating to enhance magnetic susceptibility. The pretreatment for removing elemental sulfur may be performed by any suitable means, including for example, heat pretreatment, steam pretreatment, solvent exhaust and chemical reaction.

The heat pretreatment of a sulfide ore selected from the group consisting of the metal sulfides of Groups VIB, VIIB, VIIIB, IB, IIB, IIIA, IVA and VA, or an oxide ore selected from the group consisting of bauxite, taconite, chrysocalla, apatite, titanium, silicates and metal oxides from Groups IIIV, IVB, VB, VIB, VIIB, VIIIB, IB, IIB and IVA, is conducted at a temperature of at least about 80°C, preferably for a time period of at least about 0.1 hours. The heat pretreatment step may also be conducted in the presence of one or more gaseous additives, for example, steam, nitrogen, hydrogen, carbon monoxide, hydrogen sulfide, ammonia, and sulfur dioxide. Additionally, an improved be neficiation of many of these ores can be obtained by co-treating the ore with a metal containing compound and a reducing gas under processing conditions such as to selectively enhance the magnetic susceptibility of the mineral values to the exclusion of the gangue in order to permit a physical separation of the values from the gangue.

Best Mode for Carrying Out the Invention

The process of the present invention is particularly useful for concentrating sulfide and oxide minerals. The process employs the treatment of the ore with a metal containing compound in order to selectively enhance the magnetic susceptibility of various mineral values contained within the ore. The treated mixture can then be treated by magnetic means to produce a beneficiated product.

"Enhancing the magnetic susceptibility" of the ore as used herein is intended to be defined in accordance with the following discussion. Every compound of any type has a specifically defined magnetic susceptibility, which refers to the overall attraction of the compound to a magnetic force. An alteration of the surface magnetic characteristics will alter the magnetic susceptibility. The metal treatment of the inventive process alters the surface characteristics of the ore particles in order to enhance the magnetic susceptibility of the particles. It is to be understood that the magnetic susceptibility of the particle is not actually changed, but the particle itself is changed, at least at its surface, resulting in a particle possessing a greater magnetic susceptibility than the original particle. For convenience of discussion, this alteration is termed herein as "enhancing the magnetic susceptibility" of the particle or ore itself. The sulfide minerals which are capable of undergoing a selective magnetic enhancement in accordance with the process include the metal sulfides of Groups VIB, VIIB, VIIIB, IB, IIB, IIIA, IVA and VA. These sulfides preferably specifically include the sulfides of molybdenum, tungsten, manganese, rhenium, iron, ruthenium, osmium, cobalt, rhodium, nickel, palladium, platinum, copper, gold, silver, zinc, cadmium, mercury, tin, lead, arsenic, antimony and bismuth. The metal oxide minerals which are capable of undergoing a selective magnetic enhancement in accordance with the process include the metal oxides of Groups IIIB, IVB, VB, VIB, VIIB, VIIIB, IB, IIB and IVA, the titanium silicates and oxides of Group IVB, aluminum hydrate, i.e. bauxite, of Group IIIB, taconite and apatite. It is recognized that taconite and apatite are generally classified as a type of silicate and phosphate, respectively, and it is further recognized that apatite does not contain elements generally classified as metals (other than calcium). However, for the purposes of this inventive process, they are classified as metal oxides. The preferred oxide minerals include bauxite, rutile, taconite, apatite, pyrochlore, uraninite, cuprite, cassiterite, carnotite, scheelite and hematite. The gangue minerals from which the metal sulfides or oxides can be separated include those minerals which do not undergo a sufficient magnetic susceptibility enhancement as a result of the process. These gangue minerals include, for example, silica, alumina, gypsum, muscovite, dolomite, calcite, albite and feldspars, as well as various other minerals. In general, the gangue will be composed of inorganic minerals.

In those ores which contain naturally relatively strongly magnetic constituents, such as magnetite, the magnetic material may first be removed by passing the mixture through a magnetic separator. The nonmagnetic portion obtained by this precleaning step is then subjected to the treatment with a metal containing compound.

Prior to the treatment, the ore must be ground to liberate metal ore particles from the gangue particles, if the respective components do not already exist in this liberated state. The ore may be crushed finer than necessary to achieve liberation, but this is not generally economically feasible. It is generally satisfactory to crush the ore to at least about minus

14 mesh, although some ores require finer mesh sizes.

Numerous metal containing compounds are capable of enhancing the magnetic susceptibility of the metal sulfides in accordance with the invention. Many iron containing compounds possess the capability of enhancing the magnetic susceptibility of the mineral values of the ore, as long as the compound is adaptable so as to bring the iron in the compound into contact with the mineral value under conditions such as to cause an alternation of at least a portion of the surface of the mineral value.

Iron containing compounds capable of exerting sufficient vapor pressure, with iron as a component in the vapor, so as to bring the iron into contact with the value at the reaction temperature are suitable, as well as other organic and inorganic iron containing compounds which can be dissolved and/or "dusted" and brought into contact with the mineral value contained within the ore. Preferred compounds within the vapor pressure group are those which exert a vapor pressure, with iron as a component in the vapor, of at least about 10 millimeters of mercury, more preferably of at least about 50 millimeters of mercury at the reaction temperature. Examples of groupings which fall within this vapor pressure definition include ferrocene and its derivatives and beta-diketone compounds of iron. Specific examples include ferrocene and iron acetylacetonate.

Other organic compounds which may be utilized to enhance the magnetic susceptibility include those which may be homogeneously mixed with a carrier liquid and brought into contact with the components of the ore. Such mixtures include, for example, solutions, suspensions and emulsions. These compounds must be such as to provide sufficient metal to contact the surface of the mineral value. Suitable carrier liquids include, for example, acetone, petroleum ether, naphtha, hexane, benzene and water; but this, of course, is dependent upon the particular metal compound being employed. Specific groupings include, for example, ferrocene and its derivatives and the carboxylic acid salts of iron, such as, iron octoate, iron naphthenate, iron stearate and ferric acetylacetonate.

Additionally, solid organic iron containg compounds capable of being directly mixed with the ore in solid form prossess the capability of enhancing the magnetic susceptibility of the metal sulfides. The compound must be in solid form at the mixing temperature and be of sufficiently fine particle size in order to be able to be well dispersed throughout the ore. The particle size is preferably smaller than about 20-mesh, more preferably smaller than about 100-mesh, and most preferably smaller than about 400-mesh. Compounds within this grouping include ferrocene and its derivatives, iron salts or organic acids, and beta-diketone compounds of iron. Specific examples include ferrous formate, 1,1' -diacetyl ferrocene, and 1, 1' -dihydroxymethyl ferrocene.

Various inorganic compounds are also capable of producing an enhanced magnetic susceptibility. Preferred inorganic compounds include ferrous chloride, ferric chloride and the metal carbonyls, including. for example, iron, nickel, cobalt, molybdenum, tungsten and chromium carbonyls and derivatives of these compounds. Iron carbonyl is a preferred carbonyl for imparting this magnetic susceptibility, particularly iron pentacarbonyl, iron dodecacarbonyl and iron nonacarbonyl. The more preferred metal containing compounds capable of enhancing the magnetic susceptibility are iron pentacarbonyl, ferrocene and ferric acetylacetonate, with iron pentacarbonyl being the most preferred. The process is applied by contacting the iron containing compound with the ore at a temperature wherein the iron containing compound selectively decomposes or otherwise reacts at the surface of the metal sulfide particles to alter their surface characteristics, while remaining essentially unreactive, or much less reactive, at the surface of the gangue particles. The temperature of the reaction is a critical parameter, and dependent primarily upon the particular compound and the particular ore. The preferred temperature can be determined by heating a sample of the specific iron containing compound and the specific ore together until the decomposition reaction occurs. Suitable results generally occur over a given temperature range for each system. Generally temperatures above the range cause non-selective decomposition while temperatures below the range are insufficient for the reaction to occur.

While as indicated above, techniques other than vapor injection methods may be employed as applicable depending upon the metal containing compound being utilized, the following discussion primarily applies to vapor injection techniques, specifically iron pentacarbonyl, as these are generally preferred. Similar considerations, as can be appreciated, apply to the other described, techniques. The preferred temperatures when iron pentacarbonyl is employed as the treating gas are primarily dependent upon the ore being treated. It is generally preferred to select a temperature which is within a range of 125º C, more preferably 50°C, and most preferably 15°C less than the general decomposition temperature of the iron carbonyl in the specific system. The general decomposition temperature is intended to mean the temperature at which the iron carbonyl decomposes into iron and carbon monoxide in indiscriminate fashion, causing a magnetic enhancement of the gangue as well as the metal sulfide. The "specific system" is intended to include all components and parameters, other than, of course, temperature, of the precise treatment, as the general decomposition temperature varies with different components and/or different parameters. This decomposition temperature range can be readily determined by analytical methods and often a trial and error approach is preferred to determine the precise temperature range for each specific system.

The amount of the metal containing compound used and the time of treatment can be varied to maximize the selective enhancement treatment. With respect to iron carbonyl the preferred amount employed is from about 0.1 to about 100 kilograms per metric ton of feed, more preferably from about 1 to about 50 kilograms per metric ton of feed, and most preferably from about 2 to 20 kilograms per metric ton of feed. The treatment reaction is generally conducted for a period of time of from about 0.05 to about 4 hours, more preferably from about 0.15 to about 2 hours, and most preferably from about 0.25 to about 1 hour.

After the feed mixture containing the metal sulfide or oxide values has been treated with a metal containing compound, it can then be subjected to a magnetic separation process to effect the separation of these values. Any of many commercially available magnetic separators can be used to remove these values from the gangue. For example, low or medium intensity separations can be made with a permanent magnetic drum separator, electromagnetic drum separators, induced roll separators or other configurations known to those skilled in the art. Since most sulfides or oxides are liberated at a mesh size of 65-mesh or finer, a wet magnetic separation process is more effective. Thus, high intensity, high gradient wet magnetic separators are preferred. Also, electrostatic techniques may be employed as the primary separation means, or in addition to the magnetic separation means. The selective change in surface characteristics changes the electrical conductivity of the particle in analogous fashion to changing the particle's magnetic characteristics. Additionally, due to the fact that the sulfide and oxide surface characteristics have been altered, the sulfides and oxides are often more amenable to processes such as flotation and chemical leaching.

Another embodiment of the present invention is particularly useful for concentrating sulfide or metal oxide minerals from ore mixtures containing sufficient elemental sulfur such that the sulfur interferes with the interaction of the metal containing compound and the mineral values. The process entails the pretreatment to remove elemental sulfur from the ore, thereafter treating the ore with a metal containing compound in order to selectively enhance the magnetic susceptibility of various mineral values contained within the ore. The treated mixture can then be treated by magnetic means to produce a beneficiated product.

The concentration of elemental sulfur in sulfide ores varies greatly, and may range from less than one part per million to greater than 8,000 parts per million. Although many metal oxide ores do not contain elemental sulfur in their naturually occurring state, a number of such ores do exist in the presence of varying amounts of elemental sulfur. This wide range is dependent upon the type of ore and the particular mineral deposit. Concentrations of elemental sulfur as small as one part per million, at least in some ores, are sufficient to hinder the selective magnetic susceptibility enhancement reaction. Higher concentrations of elemental sulfur generally create a greater hindrance. Therefore, essentially any removal of elemental sulfur prior to performing the magnetic susceptibility enhancement treatment improves the recovery of mineral values.

Preferably the concentration of elemental sulfur following treatment for its removal will be less than about 100 parts per million, more preferably less than about 50 parts per million and most preferably less than about 10 parts per million, based on the total weight of the ore being treated.

Essentially any process for removing elemental sulfur from the ore can be utilized as the pretreatment means. Examples of suitable processes include heat treatment, steam treatment and solvent extraction.

The heat pretreatment essentially comprises heating the ore in order to remove the elemental sulfur. It is generally preferred that the pretreatment comprise heating the ore to a temperature of from about 80°C to about 500°C, more preferably to a temperature of from about 150°C to about 350°C, and most preferably to a temperature of from about 175°C to about 250°C. This heat pretreatment is preferably maintained for at least about 0.1 hour, and more preferably for at least about 0.5 hours. Generally higher temperatures necessitate shorter periods of time in order to accomplish the pretreatment.

The heat pretreatment step may be conducted in the presence of one or more gaseous additives, and this is preferable under many circumstances. Examples of suitable gaseous additives include nitrogen, steam, carbon monoxide, carbon dioxide, ammonia, methane, air, ethane, propane, butane and other hydrocarbon compounds which exist in the gaseous state at the pretreatment temperature. Some of these additives, under certain conditions, serve as chemical reactants in removing elemental sulfur. When these additives are employed, it is preferable that they be employed in an amount of at least about 2, more preferably at least about 12, and most preferably at least about 120 cubic meters per hour per metric ton or ore being processed.

A particularly preferred additive is steam. Heat pretreatment with steam is preferably conducted within a temperature range of from about 100°C to about 500°C and more preferably from about 150°C to about 350°C and most preferably from about 175°C to about 250°C.

Preferably the pretreatment should be conducted for at least about 0.1 hours, more preferably for a least about 0.25 hours, and most preferably for at least about 0.5 hours. The amount of water preferably ranges from about 1% to about 50%, more preferably from about 5% to about 30%, and most preferably from about 10% to about 25%, based on the weight of the ore being treated.

Alternatively, the ore can be pretreated with a solvent or a combination of solvents to effect elemental sulfur removal. Examples of suitable solvents include petroleum ether, carbon tetrachloride, toluene, acetone, ethyl alcohol, methyl alcohol, ether, carbon disulfide, liquid ammonia and other compounds suitable to dissolve elemental sulfur. Preferred solvents include carbon tetrachloride, petroleum ether, toluene and acetone. The amount of a particular solvent used will be dependent on the degree of solubility the elemental sulfur exhibits in the solvent at the treatment temperature. Generally, it is preferable that the solvent be employed in an amount of at least about one half, more preferably at least about 3, and most preferably at least about 10 liters per kilogram of ore. After the initial pretreatment step to remove the elemental sulfur, the ore is treated to selectively enhance the magnetic susceptibility of the mineral values. The heat pretreatment of the present invention is conducted prior to initiating the reaction with the metal containing compound, and may be conducted independently of the sulfur removal step previously described. This pretreatment essentially comprises heating the ore in order to render the ore more receptive to the magnetic enhancement reaction. The temperature and time of heating are interrelated, and essentially higher temperatures require less time. The particular time and temperature for the pretreatment process will depend on the particular ore being beneficiated and also the metal containing compounds with which the ore is later treated. The pretreatment may occur over a relatively broad range of temperatures; however, the temperature must not exceed the decomposition temperature of the mineral value, or the temperature above which substantial vaporization would occur. It is generally preferred that the pretreatment essentially comprise heating the ore to a temperature of at least about 80°C, more preferably from about 125°C to about 450°C, and most preferably to a temperature of from about 175°C to about 250°C. It is preferred that this heat pretreatment be done for a time period of at least 0.1 hours, more preferably from about 0.20 to about 4 hours, and most preferably from about 0.25 to about 2 hours. The heat pretreatment need not be immediately followed by the magnetic enhancement reaction. Hence, the ore may be permitted to cool to ambient temperature, or any other convenient temperature, prior to conducting the magnetic susceptibility enhancement reaction. However, if the heat pretreatment is conducted at a temperature greater than the temperature of the magnetic enhancement reaction, the ore must be cooled to at least the temperature at which the magnetic, enhancement reaction will be conducted.

Another embodiment of this invention entails cotreating the ore with a metal containing compound while simultaneously treating the ore with a reducing gas. Preferred gases include those selected from the group consisting of hydrogen, carbon monoxide, ammonia, and lower hydrocarbons in the range of about C, to propylene, butane and butylene, as well as other similar reducing gases. These gases in and of themselves have no appreciable effect upon the magnetic susceptibility of the mineral values; however, they can significantly improve the results obtained over the metal containing compound treatments alone.

The metal containing compound and the gas may be introduced into the reaction chamber together or simultaneously from different inlets, as long as the reducing gas is available to metal containg compound during the treatment.

The type and amount of gas will depend to some extent upon the metal containing compound being used. Generally, the gas will be employed at a concentration of preferably at least about 1 percent, more preferably at least about 10 percent and most preferably about 100 percent of the reactor atmosphere.

The processes of this invention are not especially useful in beneficiating oxide ores which are highly naturally magnetic since such ores can be beneficiated by subjecting them to a magnetic separation process or first heating them before the magnetic process. An example of such an ore is pyrolusite. The following examples relate to the treatment of sulfide ores to enhance magnetic susceptibility. EXAMPLE 1

Samples of three different synthetic ores, 3% galena, 3% sphalerite and 5% molybdenite, obtained by grinding the mineral to minus 65-mesh and mixing with minus 65-mesh sand, were treated at 400°C with 16 kilograms of ferrocene per metric ton of ore. The ferrocene had been dissolved in petroleum ether and mixed with the ore sample. The petroleum ether was then evaporated through gentle heating. Thereafter, the treated ore sample was placed in the reactor and the temperature was slowly raised to 400°C over a two hour period. Identical samples were treated to the above procedure with the omission of ferrocene in order to obtain comparative data. The results are presented below in Table 1.

EXAMPLE 2

Samples of galena, sphalerite and molybdenite identical with those used in Example 1 were treated with 16 kilograms of ferric acetylacetonate per metric ton of ore at a temperature of 270°C for 15 minutes. The acetylacetonate was injected into the reactor in a volatilized form. Again, samples of the same ore were subjected to the above procedure with the omission of the ferric acetylacetonate in order to obtain comparative blanks. The data from these tests are presented below in Table 2.

EXAMPLE 3

A sample of chalcopyrite in a silica-alumina gangue was treated with 32 kilograms of iron carbonyl per metric ton of feed, while it was rotating in a glass reaction vessel at 125°C for 30 minutes. After purging with helium, the treated material was subjected to a magnetic separation step in a Dings cross-belt magnetic separator. Another sample of chalcopyrite in silica and alumina, identical in all respects to the first sample except that it was not treated with iron carbonyl, was also passed through the magnetic separator. The products were chemically analyzed for copper.

Results of these tests are shown in the following table:

EXAMPLE 4

A small sample of chalcocite mixed with silica was packed in a glass tube and 57-75 milliliters per minute of nitrogen gas saturated with iron carbonyl was passed through the stationary sample bed held at 195°C for 30 minutes. A hand magnet was used to separate the material into two portions, a magnetic and a nonmagnetic fraction. Microscopic examination clearly showed that the magnetic fraction was much richer in chalcocite than the nonmagnetic fraction.

EXAMPLE 5

A sample of galena in a silica-alumina matrix was treated in the same manner as described in Example 3 except it was treated with 46 kilograms of iron carbonyl per metric ton of feed while increasing the temperature from 25°C to 125°C. Another sample was treated at 115°C for 30 minutes with 32 kilograms of iron carbonyl per metric ton of feed. A third sample was not treated with iron carbonyl. All three samples were then passed through the cross-belt magnetic separator, with the results shown in the following table:

EXAMPLE 6

For this example, pure cerussite was mixed with silica and alumina. After treatment with 32 kilograms per metric ton iron carbonyl at 105°C for 30 minutes, only negligible traces of cerussite mineral were responsive to the magnet.

EXAMPLE 7

A sample of molybdenite ground to minus 65-mesh was mixed with minus 65-mesh silica sand to produce a 5% synthetic ore. A sample of this ore was treated at 140°C for 30 minutes with 8 kilograms of iron pentacarbonyl per metric ton of feed. Thereafter, the mixture was subjected to a magnetic separation process to remove the molybdenum. Pertinent data are given below:

EXAMPLE 8

Samples of galena, sphalerite and molybdenite were ground to minus 65-mesh and mixed with minus 65-mesh silica sand to produce the synthetic ores of 3% galena, 3% sphalerite and 5% molybdenite, respectively. Samples of each of these ores were treated for 30 minutes at the temperatures indicated in Table 6 with 8 kilograms of iron pentacarbonyl per metric ton of feed. Comparative results were obtained by treating another sample of each of the ores exactly the same but with the omission of the iron carbonyl. All of the samples were subjected to a magnetic separation process and the results are given below in Table 6.

EXAMPLE 9

Samples of three diferent synthetic ores, 5% molybdenite, 3% sphalerite and 3% galena all mixed with silica sand were treated for 30 minutes with 8 kilograms of iron carbonyl per metric ton of feed. Each of the samples were treated at the temperature indicated in Table 7. All of the samples were subjected to a magnetic separation process, the results of which are presented in Table 7.

EXAMPLE 10

Samples of 3% galena in Ottawa silica sand sized to minus 65-mesh, were treated in a reactor with 16 kilograms of ferrous chloride per metric ton of ore and also with 16 kilograms of ferric chloride per metric ton of ore. Thereafter the temperature of the reactor was raised to 300°C over 75 minutes. Comparative data were obtained by treating samples of the ore in the same manner but with the omission of the ferrous chloride and ferric chloride. Table 8 gives the comparative results.

EXAMPLE 11

Samples of different sphalerites were ground to minus 65-mesh and mixed with minus 65-mesh silica sand to a 3% synthetic ores. A sample of each of these ores were treated with 8 kilograms of iron pentacarbonyl per metric ton of ore for 30 minutes at the temperature indicated in Table 9. All of the samples were subjected to a magnetic separation process and the results are below in Table 9.

EXAMPLE 12

A sample of molybdenite was ground to minus 65-mesh and mixed with minus 65-mesh silica sand to produce a 5% synthetic ore. Several 1 kilogram samples of this ore were treated with iron carbonyl at a dosage and temperature indicated in Table 10 for 30 minutes. The samples were subjected to a magnetic separation process and the following results were obtained.

EXAMPLE 13

Samples of different minerals were ground to minus 65-mesh and mixed with minus 65-mesh silica sand to produce 3% synthetic ores. Each sample was treated for 30 minutes with 8 kilograms of iron carbonyl per metric ton of feed. The temperature of the treatment varied for the different minerals and is given below as are the data relating to the wet magnetic recovery of the metals.

The following examples relate to pretreating oxide ores with heat prior to treatment with the metal-containing compound to enhance magnetic susceptiblity. EXAMPLE 14

Samples of different minerals were ground to a minus 65-mesh and mixed with minus 65-mesh silica sand to produce 3% synthetic ores with the exception of carnotite which was a 5% ore. Each sample was pretreated with steam by rapidly heating the sample to 200°C under a nitrogen purge; thereafter the sample was treated for 15 minutes with 200 kilograms of steam per metric ton of sample. The reactor was then cooled under a nitrogen purge. Following this steam pretreatment each sample was treated with 8 kilograms of iron pentacarbonyl per metric ton of sample for 30 minutes at the temperature indicated in Table 1. All of the samples were then subjected to a magnetic separation process. The results are given in Table 12.

EXAMPLE 15

For comparison, additional samples of the same type of ores of Example 14 were subjected to just a steam pretreatment, and then magnetically separated. Analyses of these comparative blanks are given in Table 13.

EXAMPLE 16

Samples of different synthetic ores were prepared as indicated in Example 14. Each of the samples in this example was pretreated with heat and nitrogen by rapidly heating a reactor containing the sample to 400°C during a nitrogen purge which flowed at a rate such that one reactor volume of gas was introduced into the system every 4.3 minutes and maintaining these conditions for 15 minutes. Then the reactor was cooled under a nitrogen purge. Following this pretreatment, each sample was treated with 8 kilograms of iron pentacarbonyl per metric ton of sample for 30 minutes at the temperature indicated in Table 14. All of the samples were the subjected to a wet magnetic separation process. The results are present ed in Table 14.

EXKMPLE 17

For comparative purposes, additional samples of the same type of ores of Example 16 were subjected to just the heat and nitrogen pretreatment, and then magnetically separated. Analyses of these comparative blanks are given in Table 15.

EXAMPLE 18

Samples of different synthetic ores were prepared as indicated in Example 14. Each of the samples in this example was pretreated with heat and hydrogen by rapidly heating the reactor containing the sample to

400°C while purging it with nitrogen. This temperature was maintained for 15 minutes while hydrogen gas was passed through the reactor at a flow rate of one reactor volume of gas every 4.3 minutes. The reactor was cooled under a purge of nitrogen gas. Each sample was then treated with 8 kilograms of iron pentacarbonyl per metric ton of sample for 30 minutes at the temperature indicated in Table 16. Thereafter the samples were subjected to a wet magnetic separation process. The results are given in Table 16.

_

EXAMPLE 19

For comparative purposes, additional samples of the same type of ores of Example 18 were subjected to just the heat and hydrogen pretreatment, and then magnetically separated. Analyses of these comparative blanks are given in Table 17.

EXAMPLE 20

Samples of different synthetic ores were prepared as indicated in Example 14. Each of the samples in this example was pretreated with heat and carbon monoxide by rapidly heating the reactor containing the sample to 400°C while purging it with nitrogen. This temperature was maintained for 15 minutes while carbon monoxide gas was passed through the reactor at a flow rate of one reactor volume of gas every 4.3 minutes. The reactor was cooled under a purge of nitrogen gas. Thereafter each sample was treated with 8 kilograms of iron pentacarbonyl per metric ton of sample for 30 minutes at the temperature indicated in Tabe 18. The samples were then subjected to a wet magnetic separation process. The results are presented in Table 18.

EXAMPLE 21

For comparative purposes, additional samples of the same type of ores of Example 20 were subjected to just the heat and carbon monoxide pretreatment, and then magnetically separated. Analyses of these comparative blanks are given in Table 19.

EXAMPLE 22

For comparative purposes, samples of the same type of ores used in the preceding examples 14-21 were not given any pretreatment but were justed treated with 8 kilograms of iron pentacarbonyl per metric ton of feed for 30 minutes at the same temperature as used in the preceding examples. These samples were then magnetically separated. Additionally, another series of samples of ores were treated merely to the temperature of the iron carbonyl treatment and given no iron carbonyl treatment; these were also subjected to a magnetic separation process. Analyses of these comparative results are given below in Table 20.

EXAMPLE 23

Samples of apatite and bauxite were made into 3% synthetic ores as indicated in Example 14. Each of these samples was subjected to a pretreatment and thereafter treated with 16 kilograms of ferrocene per metric ton of sample. The ferrocene was mixed with the sample, and the temperature of the reactor was slowly raised to 400°C over a two hour period. The system was purged with nitrogen prior to and following the ferrocene treatment. Finally, the samples were subjected to a wet magnetic separation process. Each of the pretreatments, i.e., steam, heat plus nitrogen, heat plus hydrogen and heat plus carbon monoxide, were conducted in the same manner as the pretreatments in Examples 14, 16, 18 and 20, respectively.

For comparative purposes, additional samples of the same type of ores were subjected to just the pretreatment followed by wet magnetic separation. Also, samples of these ores were given no pretreatment and were subjected to only the ferrocene treatment with subsequent magnetic separation. Analyses of these comparative samples are given in Table 21.

EXAMPLE 24

Samples of different synthetic, ores were prepared as indicated in Example 14. Each of these samples was subjected to a pretreatment and thereafter treated with 16 kilograms of vaporized ferric acetylacetonate per metric ton of sample at a temperature of 270°C for a period of 30 minutes. The samples were then subjected to a magnetic separation process. Each of the pretreatments indicated in Table 11 were conducted in the same manner as described in Examples 14, 16, 18 or 20.

For comparative purposes, samples of the same type of ores were subjected to just the pretreatment followed by magnetic separation (these results are designated as blanks in Table 22). Additional samples of these ores were given no pretreatment and were subjected to only the ferric acetylacetonate treatment with subsequent magnetic separation. Analyses of these comparative samples are given below in Table 22.

EXAMPLE 25

Samples of carnotite and cuprite cynthetic ores were prepared as indicated in Example 14. A sample of each of these ores was pretreated with heat and hydrogen sulfide gas by rapidly heating the reactor containing the sample to 200^ºC while purging it with nitrogen. This temperature was maintained for 15 minutes while hydrogen sulfide gas was passed through the reactor at a flow rate of one reactor volume of gas being introduced into the system every 4.3 minutes. The reactor was cooled under a purge of nitrogen gas. Each sample was then treated with 8 kilograms of iron pentacarbonyl per metric ton of sample for 30 minutes at a temperature of 145°C in the case of carnotite and at a temperature of 125°C in the case of cuprite ore. For comparative purposes, an additional sample of each of these ores received merely the pretreatment in the manner indicated above. All of the samples were subjected to a wet magnetic separation process. Analyses of the products thus obtained are presented below in Table 23.

EXAMPLE 26

Samples of carnotite and cuprite synthetic ores were prepared as indicated in Example 14. A sample of each of these ores was pretreated with heat and sulfur dioxide gas by rapidly heating the reactor containing the sample to 400°C while purging it with nitrogen. This temperature was maintained for 15 minutes while sulfur dioxide gas was passed through the reactor at a flow rate of one reactor volume of gas being introduced every 4.3 minutes. The reactor was cooled under a purge of nitrogen gas. Each sample was then treated with 8 kilograms of iron pentacarbonyl per metric ton of sample for 30 minutes at a temperature of 145°C in the case of the carnotite ore and a temperature of 125°C in the case of the cuprite ore. For comparative purposes, an additional sample of each of these ores was subjected only to the pretreatment in the manner indicated above. All of the samples were subjected to a wet magnetic separation process and the analyses of the products thus obtained are given below in Table 24.

SXAMPLE 27

Samples of carnotite and cuprite synthetic ores were prepared as indicated in Example 14. A sample of each of these ores was pretreated with heat and ammonia by rapidly heating the reactor containing the sample to 400°C while purging it with nitrogen. This temperature was maintained for 15 minutes while ammonia gas was passed through the reactor at a flow rate of one reactor volume of gas being introduced every 4.3 minutes. The reactor was cooled under a purge of nitrogen gas. Each sample was then treated with 8 kilograms of iron pentacarbonyl per metric ton of sample for 30 minutes at a temperature of 145°C in the case of the carnotite ore and at a temperature of 125°C in the case of the cuprite ore. All of the samples were subjected to a wet magnetic separation process. The analyses of the products thus obtained are presented below in Table 25.

EXAMPLE 28

Samples of carnotite were made into 3% synthetic ores as indicated in Example 14. Each of these samples was subjected to a pretreatment and thereafter treated with 8 kilograms of iron pentacarbonyl per metric ton of sample for thirty minutes at a temperature of 135°C. The pretreatments were carried out as described in Examples 18 and 20 with the exception of time and temperature variations. The temperature and time of the pretreatment are set forth in Table 26. For comparative purposes, samples were subjected just to the pretreatment, receiving no iron carbonyl treatment. Additionally, two samples received no pretreatment with one being subjected to the iron carbonyl treatment and the other merely being heated to a temperature of 145^ºC. All of the samples were subjected to a wet magnetic separation process. Analyses of the products thus obtained are presented below in Table 26.

EXAMPLE 29

Chrysocolla was ground to a minus 65-mesh and mixed with minus 65-mesh silica sand to produce a 3% synthetic ore. A sample of this ore was pretreated with steam in the manner described in Example 14 and another sample was pretreated with heat and hydrogen sulfide gas in the manner described in Example 25. Both were then separately treated with 8 kilograms of iron pentacarbonyl per metric ton or ore for 30 minutes at a temperature of 160^ºC. For comparative purposes, additional samples of the ore were subjected to only the steam and hydrogen sulfide pretreatments. Also, two sets of samples of the ore were given no pretreatment; one was subjected to only the iron pentacarbonyl treatment and the other sample was heated to 150°C.

All of the samples were subjected to a wet magnetic separation process. Anaylses of the products thus obtained are given below in Table 27.

The following examples relate to the pretreatment of sulfide ores with heat, prior to contacting them with the metal-containing compound to enhance magnetic susceptibility. EXAMPLE 30

Samples of different minerals were ground to a minus 65-mesh and mixed with minus 65-mesh silica sand to produce 3% synthetic ores with the exception of molybdenite which was a 5% ore. A sample of each ore was pretreated with steam by rapidly heating a reactor containing the sample to 200°C under a nitrogen purge; thereafter the sample was treated for fifteen minutes with 200 kilograms of steam per metric ton of sample. The reactor was then cooled under a nitrogen purge. Following this pretreatment, each sample was treated with 8 kilograms of iron pentacarbonyl per metric ton of sample for thirty minutes at the temperature indicated in Table 28. For comparative purposes, a sample of each of these ores was only pretreated with the steam in the manner indicated above. All of the samples were then subjected to a wet magnetic separation process, and the analyses of the products thus obtained are present below in Table 28.

EXAMPLE 31

Samples of different synthetic ores were prepared as indicated in Example 30. A sample of each of the ores was pretreated with heat and nitrogen by rapidly heating a reactor containing the sample to 400°C during a nitrogen purge which flowed at a rate of one reactor volume of gas being introduced into the system every 4.3 minutes and maintaining these conditions for fifteen minutes. Then the reactor was cooled under the same type of nitrogen purge. Following this pretreatment, each sample was treated with 8 kilograms of iron pentacarbonyl per metric ton of sample for thirty minutes at the temperature indicated for the particular ore in Table 28. For comparative purposes, a sample of each of the ores was merely subjected to the heat and nitrogen pretreatment in the manner indicated above. All of the samples were then subjected to a magnetic separation process. The results are presented in Table 29.

EXAMPLE 32

Samples of different synthetic ores were prepared as indicated in Example 30 and a sample of each of the ores was pretreated with heat and hydrogen by rapidly heating the reactor containing the sample to 400^ºC while purging it with nitrogen. This temperature was maintained for fifteen minutes while hydrogen gas was passed through the reactor at a flow rate of one reactor volume of gas being introduced into the system every 4.3 minutes. The reactor was cooled under a purge of nitrogen gas. Each sample was then treated with 8 kilograms of iron pentacarbonyl per metric ton of samples for thirty minutes at the temperature indicated for the particular ore in Table 30. For comparative purposes, a sample of each of the ores was subjected to just the heat and hydrogen pretreatment. All of the samples were subjected to a wet magnetic separation process. The analyses of the products thus obtained are given below in Table 30.

EXAMPLE 33

Samples of different synthetic ores were prepared as indicated in Example 30. A sample of each of the ores was pretreated with heat and carbon monoxide by rapidly heating the reactor containing the sample to 400°C while purging it with nitrogen. This temperature was maintained for fifteen minutes while carbon monoxide gas was passed through the reactor at a flow rate of one reactor volume every 4.3 minutes. The reactor was then cooled under a purge of nitrogen gas. Each sample was then treated with 8 kilograms of iron pentacarbonyl per metric ton of sample for thirty minutes at the temperature indicated for the particular ore in Table 28. For comparative purposes, a sample of each ore was subjected to just the heat and carbon monoxide pretreatment. All of the samples underwent a wet magnetic separation process. The results are given below in Table 31.

_

EXAMPLE 34

For comparative purposes, a sample of each of the same type of ores was used in the preceeding Examples 30-33 were not given any pretreatment, but were just treated with 8 kilograms of iron pentacarbonyl per metric ton of feed for thirty minutes at the same temperature as used in the preceeding examples. Additionally, some samples of these ores were treated at the temperature of the iron carbonyl treatment but received no iron carbonyl. All of the samples were magnetically separated and the analyses of the products thus obtained are presented below in Table 32.

EXAMPLE 35

Sampes of galena were made into 3% synthetic ores as indicated in Example 30. Each of these samples was subjected to a pretreatment and thereafter treated with sixteen kilograms of ferrocene per metric ton of sample. The ferrocene was mixed with the sample and the temperature of the reactor was slowly raised to 400°C over a two hour period. The system was purged with nitrogen prior to and following the ferrocene treatment. Finally the samples were subjected to a wet magnetic separation process. Each of the pretreatments, i.e., steam, heat plus nitrogen, heat plus hydrogen, and heat plus carbonmonoxide, were conducted in the same manner as the pretreatments in Examples 30, 31, 32 and 33, respectively. For comparative purposes, additional samples of the same type of ores were subjected to just the pretreatment followed by magnetic separation. Also, two samples of this ore were given no pretreatment. One was subjected to only the ferrocene treatment and the other merely to a heating to a temperature of 400°C. These samples were subjected to wet magnetic separation process. The results of these comparative samples are given below in Table 33.

EXAMP LE 36

Samples of sphalerite were made into 3% synthetic ores as indicated in Example 30. Each of these samples was subjected to a pretreatment and thereafter treated with sixteen kilograms of ferrocene per metric ton of sample. Each of the pretreatments, i.e., steam and heat plus nitrogen, were conducted in the same manner as the pretreatments in Examples 30 and 31 respectively. The ferrocene treatment was conducted in the same manner as described in Example 35. For comparative purposes, additional samples of the same type of ore were subjecte to just the pretreatment followed by magnetic separation Samples of this ore were also given no pretreatment with one sample being subjected to only the ferrocene treatment and the other merely being heated to 400°C. All of the samples underwent a magnetic separation process. Analyses of these comparative samples are given below in Table 34.

EXAMPLE 37

Samples of molybdenite were made into 5% synthetic ore as indicated in Example 30. Each of these samples was subjected to a pretreatment and thereafter treated with sixteen kilograms of ferrocene per metric ton of sample. Each of the pretreatments, i.e., steam, heat plus nitrogen, heat plus hydrogen, and heat plus carbon monoxide were conducted in the same manner as the pretreatments in Examples 30, 31, 32 and 33, respectively The ferrocene treatment was conducted in the manner described in Example 35. For comparative purposes, additional samples of the same type of ore were subjected to just the pretreatment followed by magnetic separation. Also, samples of this ore were given no pretreatment. One was subjected to only the ferrocene treatment, and the other was merely heated to 400°C. All of the samples were subjected to a magnetic separation process. Analyses of the products thus obtained are presented below in Table 35.

EXAMPLE 38

Samples of different minerals were made into synthetic ores as indicated in Example 30. Each of these samples was subjected to a pretreatment and thereafter treated with sixteen kilograms of vaporized ferric acetylacetonate per metric ton of sample at a temperature of 270°C for thirty minutes. The pretreatments were conducted in the same manner as described in previous examples. For comparative purposes, additional samples of the same type of ores were subjected to just the pretreatment. Also, two samples of each of these ores were given no pretreatment. One was subjected to the ferrocene treatment and the other was only heated to 270°C. All of the samples were subjected to a magnetic separation process. The results of these comparative samples are given below in Table 36.

EXAMPLE 39

Samples of sphalerite were made into 3% synthetic ores as indicated in Example 30. Each of these samples was subjected to a pretreatment of heat and hydrogen gas and thereafter treated with 8 kilograms of iron pentacarbonyl per metric ton of sample for thirty minutes at a temperature of 135°C. The pretreatment was carried out as described in Example 32 with the exception of time and temperature variations. The temperature and time of the pretreatment are set forth in Table 37. For comparative purposes, samples were subjected just to the pretreatment, receiving no iron carbonyl treatment. Additionally, two samples received no pretreatment with one being subjected to the iron carbonyl treatment and the other merely being heated to a temperature of 135°C. All of the samples were subjected to a wet magnetic separation process. Analyses of the products thus obtained are present below in Table 37.

The following examples relate to the treatment of oxide ores with a metal-containing compound to enhance magnetic susceptibility, and the simultaneous treatment of the ore with a reducing gas.

EXAMPLE 40

A sample of taconite from the Mesabi range was prepared by crushing to minus 14 by 200-mesh, and passing it through a Stearns cross-belt magnetic separator to remove any naturally magnetic material. Twenty-seven grams of the non-magnetic fraction thus obtained were placed in a small glass rotating reactor and heated to 190-195°C while iron carbonyl was injected into the chamber during a 60-minute interval, providing a total of 4 kilograms of iron carbonyl per metric ton of taconite ore. The treated product was again passed through the magnetic separator, forming a magnetic fraction and a non-magnetic fraction.

The results of the above test are set forth in the following table:

EXAMPLE 41

Samples of different minerals were ground to 65- mesh and mixed with minus 65-mesh silica sand to produce 3% synthetic ores with the exception of carnotite which is a 5% ore. Each sample was treated for a period of thirty minutes with 8 kilograms of iron carbonyl per metric ton of ore. The iron carbonyl was injected as a vapor during the first 10 minutes of this thirty minute treatment. The temperature of the treatment varied for the different minerals. Additionally, for each sample treated with iron carbonyl another sample was run under the identical conditions with the omission of the iron carbonyl in order to obtain comparative data. All of the samples with the exception of hematite were subjected to a wet magnetic separation process which utilized a current of 2 amperes in the magnetic coils. The magnetic separation of hematite utilized a current of 0.2 amperes in the magnetic coils. Data are presented in Table 39 (Figures contained within brackets in Table 39 denote calculated amounts).

EXAMPLE 42

Samples of different minerals were mixed with silica sand to produce 3% synthetic ores with the exception of carnotite which is a 5% synthetic ore. Some samples were treated with ferrocene which had been dissolved in petroleum ether. This ferrocene was mixed with the ore sample and then the petroleum ether was evaporated off. Thereafter, the material was placed in a reactor and the temperature was raised to 400°C over a two-hour period. The remaining samples were treated exactly the same with the omission of ferrocene in order to obtain comparative data. Table 40 shows the comparative results.

I

EXAMPLE 43

Samples of 3% synthetic ores (carnotite is a 5% synthetic ore) were treated with sixteen kilograms of vaporized ferric acetylacetonate per metric ton of ore at a temperature of 270°C for a period of thirty minutes. Samples identical in composition were subjected to the same treatment with the omission of the ferric acetylacetonate. The comparative results are shown in Table 41.

n,

EXAMPLE 44

Several samples of 3% synthetic ores were co treated with 8 kilograms of iron pentacarbonyl per metric ton of ore and a reducing gas. Each of the cotreatment samples were heated, then the system was purged with the reducing gas for fifteen minutes at a flow rate such that one reactor volume of reducing gas was introduced into the system every 4.3 minutes. This was immediately followed by treatment with iron carbonyl for thirty minutes with the iron carbonyl being injected during the first ten minutes of treatment. Samples of the same ores were treated under the same conditions with only the reducing gas. All of the samples except hematite were subjected to a wet magnetic separation process which utilized a current of 2.0 amperes in the magnetic coils. The magnetic separation of hematite was conducted with a current of 0.2 amperes in the magnetic coils. The comparative results are shown in Table 42 (Figures given in brackets in Table 42 denote calculated amounts) .

EXAMPLE 45

A sample of scheelite was ground to minus 65-mesh and mixed with minus 65-mesh silica sand to produce a 3% synthetic ore. A sample of this ore was treated for sixty minutes with sixteen kilograms of ferrous chloride per metric ton of feed with the temperature being slowly raised to 330°C over this sixty minute treatment time. Another sample of this ore was also treated for sixty minutes with sixteen kilograms of ferric chloride per metric ton of feed with the temperature being slowly raised to 330°C over this time period. To obtain comparative results, another sample was treated exactly the same as the first two examples with the omission of the ferrous chloride and ferric chloride. Table 43 contains the results of the magnetic separation of these samples.

EXAMPLE 46

Samples of the same scheelite ore used in Example 45 were cotreated with ferrous chloride and hydrogen gas and ferric chloride and hydrogen gas. Each of these samples was treated for sixty minutes with sixteen kilograms of the iron chloride per metric ton of feed. The temperature was slowly raised to 330°C over this sixty minute treatment time. The hydrogen gas was introduced to the system prior to its heat-up at a rate of one reactor volume of hydrogen gas every 4.3 minutes for a period of fifteen minutes. Comparative results were obtained by treating another sample of the ore to the same process with the omission of the iron chloride All the samples were subjected to a magnetic separation process and Table 44 contains the comparative results of the different samples.

The following examples relate to the cotyeatment of sulfide ores with a reducing gas while treating with the metal-containing compound to enhance magnetic susceptibility. EXAMPLE 47

Samples of 3% galena in silica sand matrix, sized to a 65-mesh, were subjected to processing as follows. The first sample was merely treated at a temperature of 136°C for thirty minutes. A second sample was treated exactly the same with the additional treatment of 8 kilograms of iron pentacarbonyl per metric ton of galena mixture. Additional samples were treated as the second sample, and also were cotreated with various gase as specified in Table 45. Each of these cotreatment samples was heated to 136°C, then the system was purged with the reducing gas for fifteen minutes at a flow rate such that one reactor volume of reducing gas was introduced into the system every 4.3 minutes. This was immediately followed by the iron carbonyl treatment. The comparative results are given below in Table 45. The metal analyzed in all cases was lead.

EXAMPLE 48

Samples of 3% sphalerite mixed in a silica matrix were heated to 132^ºC for thirty minutes. All of the samples which were treated with iron carbonyl were treated for thirty minutes with the carbonyl at a rate of 8 kilograms iron carbonyl per metric ton of ore.

Again, for the samples which were cotreated with a gas, the sample was heated to 132°C and then the system was purged with the gas for fifteen minutes at a flow rate such that one reactor volume of reducing gas is introduced into the system every 4.3 minutes. This was immediately followed by the iron carbonyl treatment. The results of the analyses for zinc are presented below in Table 46.

EXAMPLE 49

Samples of 5% molybdenite mixed with a silica matrix were heated to 130°C and subjected to various treatments as described in Example 48. The results of analyses for molybdenum are shown below in Table 47.

EXAMPLE 50

Samples of 3% galena mixed in a silica matrix were cotreated with ferrocene and hydrogen and also ferrocene with carbon monoxide. The galena was also treated alone with each of the gases for comparative purposes. These processes were carried out at a temperature of 400°C and the cotreatment was carried out as in a previous example with the ferrocene being applied through a solvent deposition. Additionally, samples of 3% galena were cotreated with ferric acetylacetonate and hydrogen gas, and additional samples were treated with ferric acetylacetonate and carbon monoxide. Comparative data were also obtained by treating the galena in accordance with the same procedure with the ommission of the ferric acetylacetonate. All of these tests were made at 270°C. Again, for the cotreatments, the system was purged with the designated cotreatment gas before adding the ferric acetylacetonate as a vapor. The comparative results are presented below in Table 48.

EXAMPLE 51

Samples of 3% sphalerite mixed in a silica matrix were cotreated with ferric acetylacetonate and hydrogen gas and additional samples were treated with ferrocene and hydrogen gas as described in Example 50. Comparative data were obtained by treating the sphalerite in accordance with the same procedure but with the omission of ferric acetylacetonate and ferrocene, respectively. Table 49 gives the comparative results.

EXAMPLE 52

samples of 5% molybdenite mixed in a silica matrix were cotreated with ferric acetylacetonate and hydrogen gas and also with ferrocene and hydrogen gas as described in Example 50. Comparative data were obtained by treating the molybdenite in accordance with the same procedure but with the omission of ferric acetylacetonate and ferrocene, respectively. Table 50 gives the comparative results.

EXAMPLE 53

Samples of 3% galena in silica sand, sized to minus 65-mesh, were treated with sixteen kilograms of ferrous chloride per metric ton of ore and hydrogen gas and with sixteen kilograms of ferric chloride per metric ton of ore and hydrogen gas and were heated over a sixty minute time period to 375°C. Prior to the heating of each of these cotreatment samples, the system was purged with the hydrogen gas for fifteen minutes at a flow rate such as one reactor volume of gas was introduced into this system every 4.3 minutes. Comparative results were obtained by treating another set of samples exactly the same with the omission of ferrous chloride and ferric chloride. All of the samples were subjected to a magnetic separation process and the results are presented below in Table 51.

The follwoing examples relate to the pretreatment of sulfide and oxide ores to remove elemental sulfur prior to the treatment of the ore with the matel-containing compound to enhance magnetic susceptibility. EXAMPLE 54

Two sets of experiments were made with two different synthetic ores, 5% molybdenite and 3% sphalerite, both mixed with Ottawa sand. The first set of these samples were all treated for thirty minutes with 8 kilograms of iron carbonyl per metric ton of feed. The molybdenite ore was treated at a temperature of 140°C, whereas the sphalerite ore was treated at 135'C. The second set of samples were treated exactly the same as the first set with the exception that prior to the treatment, the elemental sulfur present with the sulfides was removed by prolonged refluxing with petroleum ether. All the samples were subjected to a wet magnetic separation process, and the analyises of the products thus obtained are presented in Table 52.

EXAMPLE 55

Samples of different minerals were ground to minus 65-mesh and mixed with minus 65-mesh silica sand to produce 3% synthetic ores. There were two sets of each sample. The first set was treated for thirty minutes with 8 kilograms of iron carbonyl per metric ton of feed. The second set of samples was pretreated to remove elemental sulfur by extraction with hot petroleum ether, followed by treatment with iron carbonyl under the same conditions as the first set. The temperature of the iron carbonyl treatment varied for the different minerals and is given in Table 53, along with the comparative results of the tests.

ibution

EXAMPLE 56

Four samples of a synthetic 3% stibnite ore were prepared by mixing minus 65-mesh stibnite ore with minus 65-mesh silica sand. The resultant 3% stibnite ore contained 274 parts per million of elemental sulfur. One sample received no pretreatment and was treated with 8 kilograms of iron pentacarbonyl per metric ton of sample at a temperature of 85°C for thirty minutes.

The other samples were pretreated with steam, hot air or petroleum ether to effect the removal of elemental sulfur and then treated with iron pentacarbonyl in the same manner as the first sample.

The steam pretreatment consisted of treating the sample with 250 kilograms of steam per metric ton of sample at a temperature of 200°C for one hour. The pretreatment with hot air to remove elemental sulfur was accomplished by spreading the sample in a thin layer in metal pans and placing these pans in a forced air drying oven having a temperature of 225°C for two hours. The petroleum ether pretreatment consisted of removing elemental sulfur from a sample through four extractions with this solvent.

All of the samples, after the iron carbonyl treatment, were subjected to a wet magnetic separation process. Analyses of the resulting products is given in Table 54.

EXAMPLE 57

Samples of a synthetic 3% galena ore were prepared by mixing minus 65-mesh galena ore with minus 65-mesh silica sand. The resultant 3% galena ore contained 26 parts per million of elemental sulfur. One sample received no pretreatment and was treated with 8 kilograms of iron pentacarbonyl per metric ton of sample at a temperature of 120°C for thirty minutes.

The other samples were pretreated with steam, hot air, petroleum ether or heat plus nitrogen to effect the removal of elemental sulfur, and then treated with iron pentacarbonyl in the same manner as the first sample. The steam, hot air and petroleum ether pretreatments were done in the same manner as described in Example 56. The pretreatment with heat and nitrogen consisted of passing nitrogen through the reactor at a flow rate of one reactor volume of gas every 4.3 minutes. These conditions were maintained for one hour.

All of the samples, after the iron carbonyl treatment, were subjected to a wet magnetic separation process. Analyses of the resulting products is given in Table 55.

EXAMPLE 58

A 150 gram sample of synthetic scheelite ore was made by blending minus 65-mesh scheelite ore (3%) in minus 65-mesh silica sand. Since the scheelite ore contained only trace amounts of sulfur, 50 parts per million of sulfur was added to the sample by dissolving 0.0075 grams of sulfur in petroleum ether, mixing the sulfur solution wiht the ore and evaporating the ether.

A 50 gram split of this sulfur spiked ore was treated with iron pentacarbonyl in a rotary glass reactor at a temperature of 135°C for 30 minutes. The iron carbonyl was injected during the first ten minutes of the treatment at a dosage of 8 kilograms of iron pentacarbonyl per metric ton of feed. The reactor was purged prior to and follwoing this treatment with nitrogen gas. The remaining 100 grams of scheelite ore was exposed to a hot air pretreatment. The material was spread in a 9-inch stainless steel pan and placed in a drying oven at a temperature of 225°C for two hours. The sample was split with one split being used for the analysis of elemental sulfur and the other split being treated with iron carbonyl. The iron pentacarbonyl treatment was conducted at 135°C for thirty minutes with a dosage of 8 kilograms of iron carbonyl per metric ton of sample being injected during the first ten minutes of the treatment. Again, the reactor was purged prior to and following the treatment with a stream of nitrogen gas. All of the samples were subjected to a wet magnetic separation process and analyses of the products thus obtained are presented below in Table 56.

Claims

1. A process for beneficiating sulfide ores, and oxide ores selected from the group consisting of taconit bauxite, apatite, titanium silicates and metal oxides of groups IIIB, IVB, VB, VIB, VIIB, VIIIB, IB, IIB and IVA, which comprises contacting the ore with a metal containing compound under conditions which cause the metal containing compound to react substantially at the surface of the metal ore particles, to the substantial, exclusion of the gangue particles so as to alter the surface characteristics of the metal ore particles thereby causing a selective enhancement of the magnetic susceptilbity of one or more of the metal ore values of the feed ore to the exclusion of the gangue in order to permit a physical separation between said values and the gangue.

2. The process of Claim 1 wherein the ore is pretreated by heating, elemental sulfur is removed, and the ore is co-treated with a reducing gas during its treatment with the metal containing compound.

3. The process of Claim 1 wherein the treated ore is subjected to a magnetic field to separate the partic which have been made magnetic from those which have not.

4. The process of Claim 1 wherein the ore in a specific system is contacted with the metal containing compound at a temperature within a range of 125°C lessthan the general decomposition temperature of the metal containing compound is the specific system for the ore being treated.

5. The process of Claim 1 wherein the metal containing compound is employed in an amount from about 0.1 ro about 100 kilograms per metric ton of ore.

6. The process of Claim 1. wherein the ore is contacted with the metal containing compound for a time period of about 0.05 to about 4 hours.

7. The process for the beneficiation of a metal sulfide ore, or oxide ore selected from the group consisting of taconite, bauxite, apatite, titanium silicates and the metal oxides of groups IIIB, IVB, VB,. VIB,. VIIB, VIIIB, IB, IIB and IVA, wherein the ore is treated with from about 0.1 to 100 kilograms of a metal containing compound per metric ton of ore at a temperature within the range of 125°C less than the general decomposition temperature of the metal containing compound in a specific system for the ore being treated for a period of time from about 0.05 to about 4 hours to cause the metal containing compound to react substantially at the surface of the metal ore particles to the substantial exclusion of the gangue particles so as to alter the surface characteristics of the metal ore values thereby causing a selective enhancement of the magnetic susceptibility of one or more of said metal ore values, to the exclusion of gangue, so as to permit a physical separation between said values and the gangue.

8. The process of Claim 1 or Claim 7 wherein the metal containing compound is an iron containing compound.

9. The process of Claim 8 wherein the iron containing compound is selected from the group consisting of ferrous chloride, ferric chloride, ferrocene derivatives, ferric acetylacetonate and ferric acetylacetonate derivatives.

10. The process of Claim 1 or Claim 7 wherein the metal containing compound is a carbonyl.

11. The process of Claim 10 wherein the carbonyl is selected from the group consisting of iron, cobalt and nickel.

12. The process of Claim 11 wherein the iron carbonyl comprises iron pentacarbonyl.

13. The process of Claim 11 wherein the metal containing compound is employed in an amount of from about 1 to about 50 kilograms per metric ton of ore and the process is carried out at a temperature within a range of 50°C less than the general decomposition temperature of the metal containing compound in a specific system for the ore being treated for a period of time from about 0.15 to about 2 hours.

14. The process of Claim 13 wherein the metal containing compound is employed in an amount of from about 2 to about 20 kilograms per metric ton of ore.

15. The process of Claim 14 wherein the metal containing compound is iron carbonyl and the treatment process is carried out at a temperature within a range of 15° less than the general composition temperature of the iron carbonyl in the specific system for the ore being treated.

16. The process of Claim 1 or Claim 7 wherein said metal values in the ore are physically separated from the gangue by a magnetic separation process.

17. The process of Claim 16 wherein the magnetic separation process is a wet magnetic separation process.

18. The process of Claim 1 or Claim 7 wherein the said metal values in the ore are physically separated from the gangue by an electrostatic technique.

19. The process of Claim 9 wherein the iron containing compound is selected from the group consisting of ferrous chloride, ferric chloride, ferrocene and ferric acetylacetonate.

20. The process of Claim 19 wherein the iron containing compound is ferrous chloride.

21. The process of Claim 19 wherein the iron containing compound is ferric chloride.

22. The process of Claim 19 wherein the iron containing compound is ferrocene.

23. The process oc Alim 22 wherein the iron containing compound is ferric acetylacetonate.

24. A process for the beneficiation of at least one of the following ores: a metal sulfide ore selected from the group consisting of galena, molybdenite, sphalerite, bornite, cinnabar, arsenopyrite, smaltite, chalcocite, chalcopyrite, orpiment, realgar, pentlandite in pyrrhotite, stibnite and tetrahedrite, and a metal oxide ore selected from the group consisting of taconite, bauxite, apatite, rutile, pyrochlore, uraninite, cuprite, cassiterite, carnotite, scheelite, hematite, which comprises, for the ore in a specific system, contacting the ore with an iron containing compound selected from the group consisting of ferrous chloride, ferric chloride, ferrocene, ferric acetylacetonate and iron pentacarbonyl at a temperature within a range of 125^ºC less than the general decomposition temperature of the iron containing compound in a specific system for the ore being treated for a period of time from about 0.05 to about 4 hours to cause the metal containing compound to react substantially at the surface of the metal ore particles to the substantial exclusion of the gangue particles so as to alter the surface characteristics of the metal ore values, thereby causing a selective enhancement of the magnetic susceptibility of one or more of said metal ore values to the exclusion of the gangue in order to permit a magnetic separation between the said metal ore values and the gangue.

25. The process of Claim 24 wherein the iron containing compound is iron pentacarbonyl employed in an amount from about one to about 50 kilograms per metric ton of ore and the process is conducted at a temperature within a range of 15°C less than the general decomposition temperature of the iron carbonyl in a specific system for the ore being treated.

26. The process of Claim 1 or Claim 7 wherein the ore is ground to liberate the metal sulfide particles prior to its treatment with the metal containing compound.

27. The process of Claim 1 or Claim 7 wherein the ore is treated with heat prior to its treatment with the metal containing compound.

28. The process of Claim 27 wherein the heat pretreatment is conducted at a temperature of at least about

80° C.

29. The process of Claim 28 wherein the heat pretreatment is conducted in the presence of a gas selected from the group consisting of steam, nitrogen, hydrogen, carbon monoxide, carbon dioxide, ammonia, hydrogen sulfide, sulfur dioxide, methane, air, ethane, propane, butane and other hydrocarbons in the gaseous state at the pretreatment temperature.

30. The process of Claim 29 wherein the gas is employed in an amount of at least about 2 cubic meters per hour per metric ton of ore being treated.

31. The process of Claim 29 wherein the gas is steam.

32. The process of Claim 31 wherein the steam pretreatment is conducted within a temperature range of from about 100° C to about 500° C for at least about 0.1 hours with from about 1 percent to about 50 weight percent water based on the weight of the ore being treated.

33. The process of Claim 1 or Claim 7 wherein the ore contains elemental sulfur, and at least a portion of said elemental sulfur is removed from the ore prior to its treatment with the metal containing compound.

34. The process of Claim 33 wherein the means for removing elemental sulfur comprises solvent extraction.

35. The process of Claim 34 wherein the solvent is selected from the group consisting of petroleum ether, carbon tetrachloride, toluene, acetone, ethyl alcohol, methyl alcohol, ether, carbon disulfide, and liquid ammonia.

36. The process of Claim 33 wherein the elemental sulfur concentration of the ore following the pretreatment for the removal of elemental sulfur is less than about 100 parts per million.

37. The process of Claim 33 wherein the elemental sulfur concentration following the pretreatment for the removal of elemental sulfur is less than about 50 parts million.

38. The process of Claim 35 wherein the solvent is petroleum ether.

39. The process of Claim 35 wherein the solvent is employed in an amount of at least about 0.5 liters of solvent per kilogram of ore.

40. The process of Claim 33 wherein the means for removing the elemental sulfur comprises heating the ore to a temperature of from about 80° C to about 500° C for a time period of at least about 0.1 hours.

41. The process of Claim 40 wherein the heat pretreatment step is conducted in the presence of a gas selected from the group consisting of nitrogen, steam, carbon monoxide, carbon dioxide, ammonia, air methane, ethane, propane, butane and other hydrocarbon compounds which exist in a gaseous state after pretreatment temperature.

42. The process of Claim 41 wherein the gas is employed in an amount of between about 2 and about 120 cubic meters per hour per metric ton of ore.

43. The process of Claim 41 wherein the gas is employed in an amount of about 12 cubic meters per hour per metric ton of ore.

44. The process of Claim 43 wherein the gas is nitrogen.

45. The process of Claim 33 wherein the elemental sulfur concentration of the ore following the pretreatment is less than about 10 parts per million.

46. The process of Claim 38 wherein the solvent petroleum ether is employed in an amount of at least about 3 liters per kilogram of ore being treated.

47. The process of Claim 1 or Claim 7 wherein the ore is cotreated with a reducing gas during the metal containing compound treatment.

48. The process of Claim 47 wherein the gas is selected from the group consisting of hydrogen, carbon monoxide, ammonia and lower hydrocarbons in the range of about C₁ to C₈.

49. The process of Claim 48 wherein the lower hydrocarbon gases in the range of about C₁ to C₈ are selected from the group consisting of methane, ethane, ethylene, propane, propylene, butane and butylene.

50. The process of Claim 47 wherein the gas is employed at a rate of at least about 1 percent of the reactor atmosphere.

51. The process of Claim 47 wherein the gas is employed at a rate of about 100 percent of the reactor atmosphere and the metal containing compound is employed in an amount of about 2 to about 20 kilograms per metric ton of ore.

52. The process of Claim 47 wherein the ore is treated with ferrocene and a reducing gas selected from the group consisting of hydrogen, carbon monoxide, ammonia, methane and ethylene.

53. The process of Claim 47 wherein the ore is treated with ferric acetylacetone and a reducing gas selected from the group consisting of hydrogen, carbon monoxide, ammonia, methane and ethylene.

54. The process of Claim 47 wherein the ore is treated with an iron carbonyl and a reducing gas selected from the group consisting of hydrogen, carbon monoxide, ammonia, methane and ethylene.

55. The process of Claim 1 or Claim 7 in which the feed ore has been preconcentrated by a separation technique.

56. The process of Claim 1 or Claim 7 in which the ore is first subjected to a magnetic separation and the resulting non-magnetic fraction comprises the feed ore.

57. The process of Claim 24 wherein the ore is heated to a temperature of at least about 80° C prior to its treatment with the iron containing compound, in the presence of a gas selected from the group con- sisting of steam, nitrogen, hydrogen, carbon monoxide, carbon dioxide, ammonia, hydrogen sulfide, sulfur dioxide, methane, air, ethane, propane, butane and other hydrocarbons in the gaseous state at the pretreatment temperature.

58. The process of Claim 57 wherein the iron containing compound is ferrocene and the heat pretreatment is conducted in the presence of a gas selected from the group consisting of steam, nitrogen, hydrogen and carbon monoxide.

59. The process of Claim 57 wherein the iron containing compound is ferric acetylacetonate and the. gas is selected from the group consisting of steam, nitrogen, hydrogen and carbon monoxide.

60. The process of Claim 57 wherein the iron con taining compound is iron carbonyl, the pretreatment is conducted at a temperature of from about 175° C to about 250° C, the gas employed is selected from the group comprising hydrogen, carbon monoxide and nitrogen, in an amount of up to 120 cubic meters per hour per metric ton of ore being treated.

61. The process of Claim 60 wherein the iron carbonyl is iron pentacarbonyl.

62. The process of Claim 27 wherein the feed ore contains elemental sulfur, and at least a portion thereof is removed from the ore prior to its treatment with the metal containing compound.

63. The process of Claim 24 wherein the feed ore contains elemental sulfur, and at least a portion of the elemental sulfur is removed from the ore prior to its treatment with the metal containing compound by means of solvent extraction wherein the solvent is selected from the group consisting of petroleum ether, carbon tetrachloride, toluene acetone, ethyl alcohol, methyl alcohol, ether, carbon disulfide and liquid ammonia.

64. The process of Claim 63 wherein the solvent is petroleum ether employed in an amount of at least about 0.5 liters of solvent per kilogram of ore.

65. The process of Claim 24 wherein the ore is cotreated with a reducing gas during the metal containing compound treatment.

66. The process of Claim 65 wherein the reducing gas employed is selected from the group consisting of methane, ethane, ethylene, propane, propylene, butane and butylene, employed at a rate of between about 1 and about 100 percent of the reactor atmosphere.

67. The process of Claim 65 wherein the ore is treated with a metal containing compound selected from the group ferrocene, ferric acetylacetonate and iron carbonyl, and the reducing gas is selected from the group consisting of hydrogen, carbon monoxide, ammonia, methane and ethylene.

68. The process of Claim 7 or Claim 24 wherein the ore is pretreated by heating to at least 80° C and elemental sulfur is removed therefrom before it is cotreated with a reducing gas during the treatment with the metal containing compound at a rate of at least about 1 percent of the reactor atmosphere, said reducing gas being selected from the group consisting of hydrogen, carbon monoxide, ammonia and the lower hydrocarbons in the range of about C₁ to C₈.