Method for reducing of manganese oxide

FIELD: non-iron industry.

SUBSTANCE: invention relates to method for reducing of manganese oxide from ore to manganese carbide. Solid metal oxide is brought into contact with gaseous reducing and cementation agent (e.g., hydrogen-hydrocarbon mixture), and optionally, with inert gas at temperature of 1000-12500C.

EFFECT: environmentally friendly method; decreased energy consumption.

21 cl, 22 dwg, 1 tbl

 

The present invention relates to a method for recovery of manganese oxides and, in particular, to a method of solid-phase recovery of oxide of manganese.

Manganese is a commercially important transition metal. To extract this transition metal from ores, different methods are used.

Manganese in combination with other elements widely distributed in the earth's crust. The most important ore consists mainly of manganese dioxide in the form of pyrolusite, psilomelan, manganite, rhodochrosite or sea nodules. Alloys of manganese conveniently be obtained by plateresco recovery of ore and smelting in electric arc furnace. Ferromanganese high carbon content also get in a blast furnace.

The present invention is based on the fact that the oxides of manganese can be recovered directly to the carbide, the carbon required for recovery is served in the form of a gaseous hydrocarbon, for example methane.

U.S. patent No. 4053301 describes a method for direct production of iron carbide from particles of iron oxide recovered using a mixture of methane (hydrocarbon)-hydrogen. In this way the fine iron ores are reduced to the metallic state by bringing into contact of the ore with hydrogen at a temperature in the range between 595°and 705° Since, in the liquefied layer. Reduced iron is then cemented using methane (hydrocarbon). Thus, the interaction of iron oxide with a mixture of methane-hydrogen-reduction products are iron carbide, and H2Oh, and the overall reaction equation of the recovery process is represented as:

3FxO+CHF4+(3-2x)H2=F3With+3H2O

As will be discussed in more detail later, the restoration of the oxide with methane (hydrocarbon) in the method according to the invention is fundamentally different from the current level of technology in relation to reducing iron oxides in that it is carried out directly in the carbide phase of a rigid material, such as ore, with the formation.

The method according to the invention may be characterized as pyrometallurgical by nature and based on the use of gaseous reductants, while the carbon required for recovery, is fed from the gas phase.

In accordance with the first aspect, the present invention relates to a method of recovering manganese oxide to manganese carbide, the method comprises bringing into contact of the oxide of manganese in solid form to a gaseous regenerating and cementing agent and, optionally, an inert gas, at an elevated temperature.

Vosstanavlivat the speaker/cementing gas may be a gaseous mixture of the hydrocarbon-hydrogen. The hydrocarbon may be alkanol, such as methane, ethane, propane, or it can represent a mixture of two or more alkanes, or can be used with natural gas, which is optionally purified before use. Preferably, a represents a hydrocarbon methane. Preferably, the hydrocarbon may be present in an amount of about 5-20%, more preferably 7-15%.

Preferably, the hydrogen pampering/cementing gas is present in an amount of from about 20 to 95%.

Optional inert carrier gas may be nitrogen or argon. The inert carrier gas may be present in amounts of from 0 to 60%.

Preferably, the manganese oxide is present in the material having a high permeability to gas, in order to allow widespread access of the reducing gas to the oxide phase. Preferably, the material processed by the method according to the invention has a high porosity, high surface area and does not melt or not sintered during the reaction of recovery. Preferably, the oxide of manganese is in the form of particles.

The material processed by the method according to the invention can constitute an ore containing one or more metal oxides. The ore may be in the form of preconcentrate or concentrate. The ore may be subjected shall be one or more pre-treatments, for example, the concentration by means of chemical and/or physical means prior to processing in accordance with the method according to the invention. Preferably, the oxide is pre-treated by calcination using hot inert or reducing gas at a temperature of about 800-1100°With removal of moisture and pre-oxidation of Mno2and MP2About3to IGOs and for the decomposition of carbonates.

Preferably, the method according to the invention is carried out at a temperature high enough to ensure that there was a reduction, but not so high as to cause significant melting or sintering of the material being processed.

Preferably, the method according to the invention is carried out at a temperature in the range approximately between 1000-1250°S, more preferably in the range between 1050-1150°C.

The method according to the invention can be implemented in any appropriate reactor. The reactor may be a reactor with the liquefied layer or a reactor with a layer of stuffing. Layer gaskets may be used if the ore particles tend to stick together. The selection of the most appropriate mode of the method depends on the composition, particle size, ore used and the composition of the gas being used.

Preferably, the CO content in almost the d reactor in the implementation of the process according to the invention is minimized. The exhaust gas from the reactor used for carrying out the method according to the present invention, may retsiklirovaniya back to the reactor. Where the exhaust gas is recycled, it is preferable that was removed before recycling into the reaction volume. Some gases (gaseous reagents, exhaust gases, or a separate thread) and can be used at any time in the reactor, before or after him, for the supply of heat or the amount of the reaction, either to the input material.

In the reaction mixture may be supplied hydrogen gas to ensure recovery of iron oxide, manganese present in the ore. The silica present in the input material, can be partly restored. For example, manganese ore with a content of silicon oxide to about 12% can be processed by the method according to the invention.

Method of recovering manganese oxide according to the invention can be carried out using the following reaction.

MPO+10/SN4=1/n7With3+WITH+20/7H2

It is easy to understand that this response is fundamentally different from the recovery of iron oxide with methane, so that the transition metal is converted directly into the carbide phase with the formation of gaseous CO.

The standard free Gibbs energy recovery IGOs to MP7With3 equal Δ°=377682-314 T j, which means that this reaction occurs spontaneously at temperatures T above, when the substances are in their standard States. The equilibrium constant for this reaction is equal to log=10/7lg(PH2/PCH4)+logPcothat equals about 10, at 1000°C, 100, 1100°and 1000, 1200°C. This indicates that the restoration of IGOs to manganese carbide is feasible and has a high degree of recovery at 1000-1200°C.

Manganese ore, in addition to the manganese oxide may contain oxides of iron, silicon and other metals. From literature it is known that in the process gas recovery, iron is easily restored by using gaseous hydrogen and/or WITH the metal States. Manganese oxide is recovered almost exclusively to its lowest oxidized state IGOs.

Examples of materials that can be processed by the method according to the invention, represent pure oxides of manganese, manganese ore Groote Eylandt, Wessels manganese ore manganese and other ores. Preferably, processing is performed on the particles having a particle size of less than about 2 mm.

Manganese ore, preferably pre-treated with hot inert or reducing gases at about 800-1100°C. Excellent kinetics which can be achieved by means of a preliminary treatment of the ore (oxide), that involves removal of moisture and decomposition of carbonate. Then, whether solid products can be recovered in the reactor with a fixed bed or in a reactor with the liquefied layer, which serves a mixture of inert gas (such as argon or nitrogen-hydrogen-methane, and in which the metal oxide is reduced to carbides. Methane is preferably fed into the reactor at such speed and in such relation to hydrogen to provide sufficient activity of carbon for the recovery of metal oxides and to maintain the desired carbon content in the final product. Hydrogen is introduced to control the activity of carbon in the gas phase.

When the temperature at which the method according to the invention, CH4is unstable. The authors found that using metastable CH4can be obtained much higher activity of carbon in the gas phase than is available at present in the normal uglehimicheskih processes.

According to another aspect of the invention features a method of recovering manganese oxide to manganese carbide, the method comprises bringing into contact of the metal oxide in solid form with gaseous cementing/regenerating agent at elevated temperature, in the presence of the agent, which expands redeliberations gaseous cementing/ reducing agent.

Preferably, the agent that extends the limits of metastability is a sulfur dissolved in the gas phase.

Technology gas recovery according to the invention can provide the following advantages over the standard methods of solid-phase plateresco recovery:

Lower operating temperature

The ability to process finely ground product

Faster kinetics

The reduction and possible elimination of coke consumption in the entire production process of the metal and, consequently, the creation of environmentally friendly technologies, because the production of coke arise harmful pollution.

The overall reduction in energy consumption.

The authors suggest that the more rapid kinetics associated with better surface contact between the reagents and the higher activity of the carbon. Preferably, the concentration of CO in the atmosphere of the reactor is reduced to a minimum, because it slows down the kinetics and reduces the degree of recovery.

Since the restoration of the ore takes place at the interface of ore/gas, the higher the porosity of the material of the oxide leads to a larger contact area and faster kinetics.

The manganese carbide, obtained using the method according to the invention, can be used for the production of alloys, in the example, by melting the carbide of the metal or directly used in the production of steel.

The present invention extends to the product of manganese carbide, obtained using the method according to the invention. The present invention is also applicable to metals and alloys, obtained from manganese carbides formed using the method according to the invention.

The invention is explained in more detail using examples, not limiting the invention.

Figure 1 presents a graph characterizing the composition of the exhaust gas when restoring clean IGOs using a mixture of methane-hydrogen-argon (15 % by volume of CH4- 20 volume % of N2- 65 vol % AG), 1150°C;

figure 2 is a graph characterizing the degree of recovery of pure IGOs using a gas mixture of CH4-N2-AG (15 % by volume of CH4- 20 vol % H2- 65 vol % AG) at different temperatures;

figure 3 is a graph characterizing the degree of recovery IGOs using a gas mixture containing methane, at various concentrations of methane, at 1200° (the content of hydrogen is maintained at 20 % by volume of H2);

figure 4 is a graph characterizing the degree of recovery IGOs using a gas mixture containing methane, with different contents of hydrogen at 1150° (the content of CH4the C is a constant, when 15 %by volume);

figure 5 is a graph characterizing the influence of CO content on the restoration of IGOs using a mixture of methane-hydrogen (10 % by volume of CH4- 20 vol % H2), 1150°C;

figure 6 - picture of the x-ray diffraction at different stages of recovery IGOs using gas mixtures containing methane, 1150°C;

7 is a graph containing curves of recovery for pure IGOs, recovered using 1 - graphite in an atmosphere of CO1at 1320°S; 2 - graphite in an argon atmosphere1at 1200C; 3 - graphite in an argon atmosphere2at 1200°S; 4 - gaseous mixture of CH4-H2-Ar, at 1200°C;

on Fig - graph characterizing restore MP Wessels ore with a mixture of methane-hydrogen (10 % by volume of CH4- 50 vol % N2- 40 vol % AG) at different temperatures;

figure 9 is a graph characterizing the restore MP Wessels ore using a gas mixture containing methane, at various concentrations of methane, at 1100° (the content of hydrogen is maintained at 50 vol % N2);

figure 10 is a graph describing the recovery of raw MP Wessels ore using a gas mixture containing methane, with different contents of hydrogen at 1100° (methane content is maintained at 10 % by volume of CH4);

figure 11 is a chart showing the progress in the formation of the crude MP Wessels ore with different particle sizes using a gas mixture containing methane. Temperature: 1100°C. the Composition of the reducing gas: 10 % by volume of CH4, 40 vol % AG and 50 % by volume of H2;

on Fig - pattern x-ray diffraction MP Wessels ore in various stages of recovery using metadatareader gas mixtures at 1000°C;

on Fig - pattern x-ray diffraction MP Wessels ore in various stages of recovery using metadatareader gas mixtures at 1100°C;

on Fig - pattern x-ray diffraction MP Wessels ore in various stages of recovery using metadatareader gas mixtures at 1200°C;

on Fig - recovery curves for MP Wessels ore recovered using graphite in an atmosphere of AG and CO, at 1300°and using a gas mixture of CH4-N2-Ah, at 1200°C;

on Fig is a graph showing the recovery of MP ore Groote Eyiandt using a mixture of methane-hydrogen (10 % by volume of CH4- 50 vol % H2- 40 vol % AG) at different temperatures;

on Fig - pattern x-ray diffraction at different stages of recovery sintered MP ores Groote Eyiandt at 1050°C;

on Fig - pattern x-ray diffraction at different stages of recovery sintered MP ores Groote Eyiandt at 1200°C;

on Fig - graph describing the effect of Cao on the rate and extent to which Stanovlenie ore Groote Eyiandt using a mixture of methane-hydrogen-argon (10 % by volume of CH 4- 50 vol % H2- 40 vol % AG) at 1150°C;

on Fig - graph describing the effect of Cao on the rate and extent of recovery of ore Groote Eyiandt using a mixture of methane-hydrogen-argon (10 % by volume of CH4- 50 vol % N2- 40 vol % AG) at 1200°C;

on Fig - pattern x-ray diffraction restored sintered MT ore Groote Eyiandt, alloy Cao, 1200°; and

on Fig - graph characterizing curves restore MP ores Groote Eyiandt recovered with graphite in an atmosphere of CO at 1300°and 1350°and using a gas mixture of CH4-N2-Ah, 1050 and 1200°C.

Pure manganese oxide Mno and two manganese ore (Groote Eyiandt, Australia and Wessels, South Africa) restore using a gas mixture containing hydrogen and methane, the metal (carbide) state at temperatures 1000°S-1200°C. Argon is used as carrier gas, although for this purpose could also be used and nitrogen, or nothing at all be used. The degree and rate of recovery of manganese oxide or manganese ore is monitored using a mass spectrometer. It is experimentally confirmed that the reduction of the oxide of manganese is happening with education in accordance with reaction (1). This can be seen in figure 1, which represents the composition of the exhaust g is for when restoring clean IGOs using a gas mixture of CH 4-N2-AG (15 % by volume of CH4, 20 volume % of N2) at 1150°C.

1) Recovery net IGOs

The rate and extent of recovery of manganese oxide as a function of temperature are illustrated in figure 2. The degree of recovery of manganese close to 100% in the temperature range 1000°S-1200°C. the Rate of recovery of manganese oxide increases with increasing temperature. Recovery IGOs also investigated as a function of gas composition. The results are presented in figure 3-5.

The recovered samples are analyzed using x-ray diffraction (XRD). Figure 6 presents the picture of x-ray diffraction at different stages of recovery clean IGOs at 1150°C. Most similar XRD pattern to manganese carbide corresponds MP7With3. Figure 7 presents curves restore clean IGOs, recovered at 1200°using graphite in an argon atmosphere, at 1320°using graphite, CO, and using a gas mixture of CH4-H2-Ar. The recovery rate of IGOs with gas CH4-N2-AG is 10 times greater than graphite in argon and 20 times greater than graphite in an atmosphere WITH at 1320°C.

Optimal conditions for recovery IGOs to phase carbide in the above experiments are as follows:

a) those who temperature: 1200° C, below the melting temperature of manganese,

b) the concentration of methane in the gas phase: 10-15 vol%, (C) the concentration of hydrogen in the gas phase: 20-90 %by volume.

2. Recovery of manganese ore

The experiments are carried out on manganese ores from Wessels Mines, South Africa and Groote Eyiandt, Australia. Their compositions are given in the table below.

Table

Composition Wessels manganese ores and Groote Eyiandt (G.E.)
OreMnOSiO2Fe2O3Al2O3CaOBaOTo2ONa2OTiO2
Wessels62.23.215.710.3515.40.40.0070.0270.013
G.E.79.44.49.601.190.030.81.300.300.15

The difference between these ores are as follows:

- MP Wessels ore has more Fe (11%) and CaO (5,4%), compared to a 6.7% Fe and 0.03% CaO in the ore Groote Eyiandt.

- The distribution of iron in the matrix Wessels ore is more homogeneous. Fe ores in Groote Eyiandt concentrated along the cleavage planes of ore.

- Prisutstvie the oxides of alkali metals (1.3% in 2Oh and 0.3% Na2O) and low CaO content in the ore Groote Eyiandt lowers the melting point of the ore. MP Wessels ore contains 74 ppm, K2O and 275 ppm Na2O.

- MP Wessels ore contains fewer SiO2(3.2%) and Al2O3(0,351%)when compared with the MP ore Groote Eyiandt, with 4.38% SiO2and 1,19% Al2O3.

2.1 Recovering MP Wessels ore

Experimental data on the degree and speed of recovery of ore as a function of temperature, gas composition and particle size of the ore presented on Fig-11. The rate of recovery of manganese ore Wessels increases with temperature. The degree of recovery of manganese is close to 100% in the temperature range from 1000°With up to 1200°

The recovered samples are analyzed using XRD. On Fig-14 presents a typical picture of the x-ray diffraction at different stages of recovery Wessels manganese ore at 1000, 1100 and 1200°C. the Carbide ferromanganese is identified as (MP, Fe)7With3.

On Fig presents recovery curves for MP Wessels ore recovered using graphite (uglehimicheskiy process) and with the help of CH4-N2-AG. The recovery rate of MP Wessels ore with gas CH4-N2-AG at 1200°is much greater than with graphite in an argon atmosphere, or in WITH, at 1300°C. Restored the e manganese ore with solid carbon is not completed even at 1350° C.

The optimal conditions for recovery MP Wessels ore are as follows: a) temperature: 1150°S, which is below the softening temperature for this type of ore, (b) methane concentration: 10-15 vol%, (C) particle size range: 1-3 mm.

Phase analysis proves that MP Wessels ore is restored to the metal (carbide) status with the formation of [Fe1-x, Mnx]7C3. Non-metallic phase contains oxides of silicon, aluminum, calcium, barium and other impurities.

The degree of recovery of manganese ore in optimal conditions close to 100%. If restoration is not completed (experimental conditions are not optimal), manganese oxide is observed in the slag phase, while the iron, as a rule, fully restored to the metal phase.

2.2 Restore MP ores Groote Eyiandt

Phase analysis shows that MT ore Groote Eyiandt is not homogeneous: ((1)) the composition of the ore depends on the particle size of the ore, ((2)) is detected individual silicon phase, and ((3)) the iron oxide is inhomogeneously distributed in the ore/ primarily along the cleavage planes. To obtain a homogeneous ore intended for restoration experiments, the fine part of the crushed ore (100 microns) is sintered in a muffle furnace at 1200°C, for 5 hours in air. Spec is nnow ore is then broken into pieces and grind to 1.0 mm

Experimental data on the degree and speed of recovery of ore as a function of temperature are presented in Fig. The speed of recovery of manganese ore Groote Eyiaudt increase with an increase in temperature from 1000 to 1050°C. They practically do not depend on temperature in the temperature range 1050-1100°and decreases with further increase in temperature. The optimum temperature for recovery of sintered ore is 1050-1100°C. the Degree of recovery is greater than 90%. Picture of x-ray diffraction obtained at different stages of recovery, at 1050 and 1200°presented on Fig and 18. At higher temperatures, there is considerable education, tephroite (Mn2SiO4), it has a low melting temperature. Adding lime (Cao), ore greatly increases the rate and extent of recovery at elevated temperature (Fig-20). Ore, alloy 10-15% Cao at 1200°With, does not contain tephroite (Fig). On Fig presents a comparison of recovery curves MP ores Groote Eyiandt restored using graphite (uglehimicheskiy process) and using gas mixtures containing methane.

The optimal conditions for the recovery of MP ore Groote Eyiandt are the following: a) temperature: 1050-1100°C, b) methane concentration: 10-15 vol%, (C) the range of sizes cha is TIC: 1-3 mm. It is recommended to add lime to the ore GE in the amount of 10-15 mass %. The optimum temperature recovery in this case is 1100-1200°under the same other conditions.

The person skilled in the art it is clear that there are numerous modifications of the invention in comparison with the above examples, is not beyond the scope described in the application of the invention. Presents examples should therefore be considered in all respects as illustrative and not restrictive.

1. Method of recovering manganese oxide to manganese carbide, which is brought into contact manganese oxide in solid form to a gaseous regenerating/a cementing agent, characterized in that the recovery is carried out at a temperature in the range of about 1000-1250°S, and optionally in the presence of inert gas, and restoring/a cementing agent contains gaseous hydrocarbons.

2. The method according to claim 1, characterized in that the gaseous regenerating/a cementing agent is a gaseous mixture of hydrogen-hydrocarbon.

3. The method according to claim 2, characterized in that the hydrocarbon is chosen from the group consisting of methane, ethane, propane and mixtures of two or more of them.

4. The method according to claim 3, characterized in that the hydrocarbon is a meta is.

5. The method according to claim 1, characterized in that the regenerating/a cementing agent is a gaseous mixture of hydrogen/natural gas.

6. The method according to claim 1, characterized in that the inert gas is nitrogen or argon.

7. The method according to claim 2, characterized in that the hydrocarbon is present in an amount of about 5-20%.

8. The method according to claim 2, characterized in that the hydrogen is present in an amount of about 20-95%.

9. The method according to any one of claims 1 to 8, characterized in that the inert gas is present in an amount of about 0 to 60%.

10. The method according to claim 1, characterized in that the temperature is in the range of about 1050-1150°C.

11. The method according to claim 1, characterized in that the manganese oxide recovered from ores containing manganese oxide.

12. The method according to claim 11, characterized in that the ore containing manganese oxide is manganese ore.

13. The method according to item 12, wherein the manganese ore is a manganese ore Groote Eylandt.

14. The method according to item 12, wherein the manganese ore is a manganese ore Wessels.

15. The method according to claim 1, characterized in that the manganese oxide restore from the intermediate concentrate or ore concentrate.

16. The method according to claim 1, characterized in that the ore is pre-treated by calcination using a hot inert or a reducing gas.

17. The method according to claim 1, characterized in that the recovery of manganese oxide to manganese carbide is carried out in the presence of an agent that extends the limits of metastability cementing/reducing agent.

18. The method according to 17, wherein the agent that extends the limits of metastability cementing/reducing agent is sulfur.

19. The manganese carbide, characterized in that it is obtained by the method according to any one of claims 1 to 18.

20. The manganese carbide according to claim 19, characterized in that it is used to produce the alloy.

21. The manganese carbide according to claim 20, characterized in that the alloy is a steel.



 

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1 dwg, 1 tbl, 3 ex

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