Method for enriching manganese from low-grade manganese carbonate ore

Abstract

The invention discloses a method for enriching manganese from low-grade manganese carbonate ore, and belongs to the field of mineral processing. According to the method, low-grade manganese carbonate ore and sodium salt are mixed and roasted, a roasted material with a manganese phase mainly comprising magnetic manganous-manganic oxide is obtained, the roasted material is subjected to quenching, ore grinding and magnetic separation, manganese-rich concentrate is recycled, the manganese recovery rate of the method reaches 91% or above, the manganese grade of the manganese-rich concentrate is higher than 48%, and magnetic separation tailings can be used for mine backfilling or used as roadbed materials. The method is simple, efficient and green, compared with an existing physical beneficiation method (high-gradient strong magnetic separation), the Mn enrichment rate is greatly increased, and compared with an existing chemical beneficiation method (acid leaching, electrolysis and smelting), the investment is small, the Mn extraction process is short, equipment operation is easy, no acid and alkali waste liquid is generated, and little or no greenhouse gas is discharged.

Description

Technical Field

[0001] The invention relates to a method for processing manganese carbonate ore, in particular to a method for enriching manganese in low-grade manganese carbonate ore, and belongs to the field of mineral processing. Background Art

[0002] In recent years, the rapid development of the global new energy, electronics, and steel industries has driven a sharp increase in the demand for manganese products. Manganese carbonate ore is a high-quality manganese source for the preparation of manganese sulfate for batteries, manganese tetraoxide for soft ferrites, and metallic manganese for alloys. At present, except for a very small number of high-quality manganese ores that have been developed, most manganese carbonate ores have not been effectively utilized due to their low manganese content (7% < Mn < 22%), fine impurity distribution, and complex composition (high phosphorus, high iron, and high silicon).

[0003] In the prior art, high gradient strong magnetic separation, sulfuric acid leaching, electrolysis, smelting and other methods have been reported to be used for the enrichment of Mn in low-grade manganese carbonate ore. For example, Chinese patents CN117696239A, CN116251664A, and CN115555127A use wet strong magnetic separation to enrich low-grade manganese carbonate ore, that is, the crushed fine-grained ore powder is soaked in a pool containing an anti-mudification agent, and more than 90% of the manganese concentrate is recovered by gradient strong magnetic separation. This process can increase the Mn grade in the ore from about 11% to 16-18%. However, the limited improvement efficiency and high power consumption do not have a competitive advantage compared to the efficient chemical enrichment process. At present, this method is more used for the pretreatment of ultra-low-grade manganese carbonate ore to improve the manganese grade. For example, Chinese patents CN118186235A, CN117604244A, CN114855220A, CN105441696A, CN105483399A, CN105296751A, etc. disclose the use of sulfuric acid leaching to enrich manganese. The specific process is: low-grade manganese carbonate ore is directly leached with sulfuric acid or electrolytic anode liquid to obtain a manganese sulfate-rich solution, and the Ca is removed by neutralization and iron removal, fluorination or ammoniation. 2+ Mg 2+, heavy metal ions and other impurity elements, precipitation or extraction is used to obtain manganese slag or high-purity manganese-rich liquid. The difference between these patented technologies is that different leaching agents or more efficient impurity removal processes have been developed for each processing link. At present, sulfuric acid leaching is a typical process for extracting manganese from medium- and high-grade manganese carbonate ore. However, when facing domestic low-grade manganese carbonate ore, the operation of this process has the following problems: (1) Low-grade manganese carbonate ore contains a large amount of clay minerals, which makes it very easy to muddy, which in turn causes a significant increase in the difficulty of filtration and the consumption of leaching solution during sulfuric acid leaching. It is also easy to form precipitation blockage, thereby affecting the stirring effect and ultimately reducing the manganese leaching rate; (2) It is difficult to remove impurities from the leaching solution. The impurity content in low-grade manganese carbonate ore is much higher than that in medium- and high-grade manganese carbonate ore. In addition to consuming more precipitants, a small amount of basic manganese sulfate and other types of sulfates will inevitably be mixed into the manganese precipitate in the manganese precipitation process. In addition, a large amount of water-soluble K + 、Na + , Ca 2+ Mg 2+ The presence of plasma leads to the Mn 2+ The extraction pressure increases exponentially; (3) high energy consumption and severe environmental pollution. During large-scale production, the process of acid leaching, impurity removal, precipitation, etc. is long and complicated, and the equipment operation is cumbersome. This not only consumes huge energy, but also produces a large amount of acid and alkali waste liquid and a small amount of organic waste water, causing huge pollution to the environment. In addition, for example, Chinese patents CN118048664A, CN107586951A, CN104803419A, and CN102492956A disclose methods for treating low-grade manganese carbonate ore by electrolysis, which is actually an improved version of the sulfuric acid leaching method, that is, the sulfuric acid leaching process is repeated first, and then the selective electroreduction of Mn is carried out at the cathode of the electrolytic cell. 2+ It is metallic Mn. This method belongs to the manganese refining process. Although it simplifies the traditional chemical precipitant impurity removal process and significantly improves the Mn grade, the use of electrolytic equipment with high investment cost, complex operation and extremely energy-consuming greatly increases the production cost. Chinese patent CN215628218U discloses the use of coke thermal reduction to reduce low-grade manganese carbonate ore to silicon-manganese alloy. This method realizes the effective utilization of low-grade manganese carbonate ore, but compared with the existing mainstream process of producing silicon-manganese alloy from pyrolusite, this method has high energy consumption and production costs and does not have a competitive advantage. Chinese patent CN107326198A also uses carbon thermal reduction to reduce low-grade high-phosphorus manganese carbonate ore to low-phosphorus manganese-rich slag. This process can be regarded as a front-end process for obtaining silicon-manganese alloy. Although the purpose of dephosphorization and manganese enrichment is achieved, the carbon emissions are higher and the energy consumption is also the same. Summary of the invention

[0004] The physical manganese enrichment method of low-grade manganese carbonate ore in the prior art has the disadvantages of low enrichment rate and limited manganese grade improvement, while the chemical enrichment method has the problems of long process flow, complicated equipment operation, large acid and alkali waste liquid discharge, high carbon emission and energy consumption, etc. The purpose of the present invention is to provide a method for enriching manganese from low-grade manganese carbonate ore, which is simple, fast, clean, efficient, low-consumption, low-cost, and has no or low carbon emission, especially the Mn recovery rate is more than 91%, and the Mn grade in the manganese-rich concentrate is more than 48%.

[0005] In order to achieve the above technical purpose, the present invention provides a method for enriching manganese from low-grade manganese carbonate ore. The method comprises the following steps: mixing low-grade manganese carbonate ore and sodium salt and roasting to obtain a roasted material in which the manganese phase is mainly magnetic manganese tetraoxide; and the roasted material is subjected to rapid cooling, grinding and magnetic separation to recover a manganese-rich concentrate.

[0006] In the low-grade manganese carbonate ore to which the present invention relates, elements such as manganese, iron, silicon, calcium, magnesium, aluminum, potassium, sodium, phosphorus, and sulfur are usually present in the form of manganese carbonate, iron carbonate / pyrite / iron oxide, quartz, dolomite, mica, chlorite, and albite, respectively. The clay mineral components contained in the low-grade manganese carbonate ore cause the manganese carbonate ore to easily undergo mudification when it encounters a solution, which greatly increases the difficulty and cost of its wet leaching. The key to the present invention is to use a direct high-temperature roasting method to treat the manganese carbonate ore to achieve the conversion of the manganese carbonate phase to the magnetic manganese tetraoxide component, which can avoid the mudification phenomenon during the wet leaching process and eliminate the use of acid leaching solution and alkaline precipitant. In the roasting process, the orderly decomposition and mineral phase reconstruction of each component in the manganese carbonate ore can be achieved, wherein manganese carbonate, iron carbonate, and pyrite are first thermally decomposed into MnO and FeO, and MnO is further converted into magnetic manganese tetraoxide. The main gangue mineral quartz in manganese carbonate and other dolomite and clay mineral components are thermally decomposed to produce CaO, MgO, Al 2 O 3 , K 2 O、Na 2 O.P 2 O 5 The magnesium source additives react with each other to form non-magnetic silicates, thereby reducing the consumption of manganese and iron components by impurity elements. At the same time, in order to reduce the inevitable combination of silicon with Mn and Fe oxides, and further reduce Al 2 O 3 The residue can be reacted with Si and Al to form non-magnetic sodium aluminosilicate by introducing an appropriate amount of sodium salt. On the basis of roasting, magnetic manganese tetraoxide and non-magnetic minerals can be separated by magnetic separation to obtain high-grade manganese-rich concentrate. The magnetic separation tailings do not contain toxic components and have stable physical and chemical properties, so they can be directly reused as mine backfill or roadbed materials.

[0007] As a preferred solution, the manganese grade of the low-grade manganese carbonate ore is 4%≤Mn≤30%.

[0008] As a preferred solution, the sodium salt includes at least one of sodium carbonate, sodium bicarbonate, sodium hydroxide, sodium chloride, sodium sulfate, sodium sulfite, sodium sulfide, sodium hydrosulfide, sodium thiosulfate, sodium oxalate, and sodium peroxide. The sodium salt mainly provides sodium ions, which react with Si and Al in low-grade manganese carbonate ore to convert into non-magnetic sodium aluminosilicate, reduce the combination of manganese oxide with silicon and aluminum, and improve the manganese recovery rate.

[0009] As a preferred solution, the low-grade manganese carbonate ore and the sodium salt are mixed according to the following mass ratio: 0.01≤(Mn+Fe+Al+Si) / Na≤6.28. If the ratio of sodium salt is too low, part of manganese will be combined with silicon and aluminum and it will be difficult to recover effectively. If the ratio of sodium salt is too high, it is easy to produce a glass phase during the roasting process, which is not conducive to the subsequent ball milling and magnetic separation.

[0010] As a preferred solution, the low-grade manganese carbonate ore is ground to a particle size that satisfies a particle size of less than 200 meshes, and the mass percentage of the particle size is not less than 95%. Grinding the manganese carbonate ore to an appropriate particle size is beneficial to the rapid decomposition and smooth conversion of the manganese carbonate ore during the roasting process.

[0011] As a preferred solution, the roasting conditions are: the roasting temperature is 300-1000°C, the roasting atmosphere is an oxidizing atmosphere, a neutral atmosphere or a weakly reducing atmosphere, and the roasting time is 5-120min. By controlling the roasting atmosphere and the roasting temperature, manganese carbonate can be smoothly converted into magnetic manganese tetraoxide after decomposition, and the iron phase is transformed into non-magnetic hematite, and at the same time, it can prevent manganese tetraoxide from further oxidizing with impurities such as calcium, magnesium, and silicon to generate impurity phases such as calcium manganate, magnesium manganate, and manganese silicate. Therefore, controlling the roasting temperature and atmosphere roasting can achieve the orderly decomposition of each component in the manganese carbonate ore and the reconstruction of the ore phase, and finally selectively convert manganese carbonate into magnetic manganese tetraoxide. The roasting temperature is further preferably 550-1000°C. Using microwave suspension roasting, it can not only uniform the thermal field and increase the heating area of ​​the manganese carbonate mineral particles, but also realize the rapid and smooth conversion of manganese carbonate to magnetic manganese-rich components within 10-30min. This roasting method is different from conventional roasting. The rapidity of microwave heating and the penetration of microwave radiation enable the manganese carbonate ore to be heated evenly in a short period of time, thereby reducing energy consumption and shortening processing time.

[0012] As a preferred solution, the oxidizing atmosphere is an atmosphere in which the volume content of oxygen does not exceed 58%. The neutral atmosphere is a nitrogen atmosphere or an inert atmosphere. The weak reducing atmosphere is an atmosphere in which the volume content of reducing gas is less than 2.63%. In addition to oxygen in the oxidizing atmosphere, other gases may be non-reactive gases such as nitrogen or inert gases. The neutral atmosphere may be composed of 100% inert gases or non-reactive gases such as nitrogen. The volume ratio of reducing gas in the weak reducing atmosphere is preferably 0.0001 to 2.63 vol.%, and reducing gases such as CO. If the reduction potential of the atmosphere is too high, it is easy to cause iron to be converted into magnetite, and selective recovery of manganese cannot be achieved; if the oxygen potential of the atmosphere is too high, it will cause manganese to be difficult to convert into magnetic manganese tetraoxide, and the solution will produce other mineral components of manganese.

[0013] As a preferred solution, the roasted material is ground to a particle size that satisfies a particle size of less than 300 meshes, and the mass percentage of the particle size is 100%. By grinding the roasted material, the dissociation of the various phases in the roasted material can be achieved, and the grade of the magnetically separated manganese concentrate and the recovery rate of the manganese concentrate can be improved. Theoretically, the finer the grinding particle size, the more complete the dissociation of the magnetic manganese component and other non-magnetic silicates, and the better the subsequent magnetic separation effect.

[0014] As a preferred solution, the magnetic field strength used in the magnetic separation is 100 to 5000 Gs.

[0015] As a preferred solution, the roasted material needs to be rapidly cooled. Rapid cooling can prevent the solid phase reaction of manganese tetraoxide and other impurities such as iron, calcium, magnesium, etc. during the cooling process, and avoid the formation of ferric manganate, calcium manganate, magnesium manganate, etc., which causes the quality of manganese-rich concentrate to decrease. Rapid cooling can be carried out by water cooling or flowing air cooling.

[0016] Compared with the prior art, the technical solution of the present invention has the following beneficial technical effects:

[0017] (1) The method for enriching manganese from low-grade manganese carbonate ore provided by the present invention has a simple process flow, low equipment requirements, low energy consumption, small investment, and is green and environmentally friendly. It does not require any wet leaching and precipitation steps. It can simply, quickly, efficiently, and cleanly enrich manganese by only relying on conventional atmosphere roasting furnaces and ball mill magnetic separation equipment to treat manganese carbonate ore, and is easy to industrialize.

[0018] (2) The method for enriching manganese in low-grade manganese carbonate ore provided by the present invention can achieve efficient enrichment of manganese in low-grade manganese carbonate ore through simple roasting and magnetic separation. More specifically, by changing the roasting temperature and the roasting atmosphere to flexibly adjust the chemical composition of the manganese-rich component, manganese carbonate can be highly selectively converted into magnetic manganese tetraoxide. This magnetic manganese mineral has high added value. On this basis, the purpose of enriching manganese ore can be achieved through simple magnetic separation.

[0019] (3) The method for enriching manganese from low-grade manganese carbonate ore provided by the present invention has a significant manganese enrichment effect, with a Mn recovery rate of more than 91% and a Mn grade of more than 48% in the manganese-rich concentrate.

[0020] (4) The method for enriching manganese from low-grade manganese carbonate ore provided by the present invention has the advantage of harmless production. After manganese enrichment is achieved, the tailings produced are non-toxic and have stable physical and chemical properties, and can be further used for mine backfill or as roadbed materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a process flow chart for enriching manganese from low-grade manganese carbonate ore in Example 1.

[0022] Figure 2 The phase composition of the manganese carbonate ore and manganese-rich concentrate product of Example 1. DETAILED DESCRIPTION

[0023] The following specific examples are intended to further illustrate the present invention, rather than to limit the scope of protection of the claims of the present invention.

[0024] Example 1

[0025] Manganese carbonate ore, containing 10.08% manganese, sodium source additive is sodium bicarbonate, element ratio meets (Mn+Fe+Al+Si) / Na=0.56, mineral co-grinding fineness: -200 mesh 100%, weigh 10g of mixed powder, according to Figure 1 The process flow is as follows: (1) The roasting furnace is heated to 750°C, the roasting atmosphere is air atmosphere, the weighed powder sample is directly placed in the roasting furnace, and the roasting time is set to 45 minutes; (2) After the roasting is completed, the roasted sample is quickly taken out and rapidly cooled under flowing air; (3) The cooled material is ball-milled to a particle size of less than 300 mesh and the mass percentage of the particle size is 100%; the ground material is magnetically separated with a magnetic field strength of 3000Gs. The magnetic concentrate is analyzed for production quality indicators, chemical elements and phases. The results in Table 1 show that the manganese recovery rate is 91.23% and the manganese grade of the manganese-rich concentrate is 54.49%. Figure 2 The results show that the chemical phase of manganese-rich concentrate is mainly manganese tetraoxide.

[0026] Table 1 Main composition of manganese carbonate ore and manganese-rich concentrate

[0027]

[0028] Example 2

[0029] Manganese carbonate ore, containing 14.88% manganese, sodium source additive is sodium chloride, element ratio meets (Mn+Fe+Al+Si) / Na=2.88, grinding fineness: -400 mesh 100%, weigh 10g sample, according to Figure 1 The process flow is as follows: (1) the temperature of the calcining furnace is raised to 1000°C, and the calcining atmosphere is a neutral atmosphere (100 vol.% N 2 ), put the weighed powder sample into the roasting furnace, and set the roasting time to 120min; (2) after the roasting is completed, quickly take out the roasted sample and cool it rapidly under flowing air; (3) ball mill the cooled sample to a particle size less than 400 mesh with a mass percentage of 100%; (4) magnetic separation is performed on the ground powder, and the magnetic separation intensity is set to 600Gs. The results in Table 2 show that the recovery rate of Mn is 96.47%, the manganese grade of the manganese-rich concentrate is 51.33%, and the manganese phase is manganese tetraoxide.

[0030] Table 2 Main composition of manganese carbonate ore and manganese-rich concentrate

[0031]

[0032] Example 3

[0033] Manganese carbonate ore, containing 27.79% manganese, sodium oxalate as sodium source additive, element ratio meets (Mn+Fe+Al+Si) / Na=3.79, grinding fineness: -300 mesh 100%, weigh 10g sample, according to Figure 1 The process flow is as follows: (1) The calcination furnace is a microwave suspension calcination reactor, the calcination temperature is set to 650°C (in addition, 550, 800, 1000°C), and the calcination atmosphere is a weak reducing atmosphere (0.05 vol.% CO / (CO+CO)). 2 )), the weighed powder sample was placed in a calcination furnace for 10 min; (2) after the calcination was completed, the microwave reactor was quickly turned off and N 2 And use circulating cooling water to quickly cool the roasting chamber to achieve rapid cooling of the roasted sample; (3) the cooled roasted sample is ball milled to a particle size less than 325 mesh, and the mass percentage of the particle size is 100%; (4) the ground powder is subjected to magnetic separation, and the magnetic separation intensity is set to 4000Gs. This embodiment conducts a comparative experiment on the roasting temperature, that is, other operating conditions are exactly the same. The test results show that with the increase of roasting temperature, the recovery rate of Mn increases from 91.08% to 93.03%, and the manganese grade of the manganese-rich concentrate increases from 54.77% to 63.62%. This shows that under a weak reducing atmosphere, a high roasting temperature is conducive to the conversion of manganese. Phase analysis shows that the main components of the three manganese-rich concentrates are all manganese tetraoxide.

[0034] Table 3 Main composition of manganese carbonate ore and manganese-rich concentrate

[0035]

[0036] Comparative Example 1

[0037] Relative to Example 1, the only difference is: no sodium salt additive is added. Test results show that, without the sodium salt additive, the manganese recovery rate of manganese-rich concentrate is 83.62%, and the manganese grade is 41.77%. Although the ore phase composition of manganese-rich concentrate is spinel phase (i.e., consistent with the physical phase structure of manganese-rich oxide), the chemical composition shows that the recovery rate of aluminum in the product reaches 58%, i.e., aluminum enters the manganese-rich oxide lattice in the form of ion doping. This lattice doping causes the aluminum component to be extremely difficult to remove. In addition, the content of silicon dioxide in the manganese-rich concentrate reaches 10.82%, and the microscopic morphology characterization results illustrate that silicon is attached to the manganese-rich oxide grains. On the one hand, the presence of aluminum-silicon impurities reduces the quality of manganese-rich concentrate, and on the other hand also increases the difficulty of subsequent impurity removal.

[0038] Comparative Example 2

[0039] The only difference with respect to Example 3 is that the reducing atmosphere is 5.0 vol.% CO / (CO+CO 2 ). The test results show that the yield of manganese-rich concentrate is only 28.17% under the magnetic field strength when the reduction potential is increased, and the manganese recovery rate and manganese grade are 11.63% and 46.11% respectively. The increase in CO concentration causes manganese carbonate to remain in the form of manganous oxide after decomposition. At 1000℃, manganous oxide is extremely active and combines with other impurity elements to form new feldspar with complex composition, resulting in a decrease in manganese recovery rate.

Claims

1. A method for enriching manganese from low-grade manganese carbonate ore, characterized in that: The low-grade manganese carbonate ore and sodium salt are mixed and roasted to obtain a roasted material whose manganese phase is mainly magnetic manganese tetraoxide. The roasted material is subjected to rapid cooling, grinding and magnetic separation to recover a manganese-rich concentrate.

2. The method for enriching manganese from low-grade manganese carbonate ore according to claim 1, characterized in that: The manganese grade of the low-grade manganese carbonate ore is 4%≤Mn≤30%.

3. The method for enriching manganese from low-grade manganese carbonate ore according to claim 1, characterized in that: The sodium salt includes at least one of sodium carbonate, sodium bicarbonate, sodium hydroxide, sodium chloride, sodium sulfate, sodium sulfite, sodium sulfide, sodium hydrosulfide, sodium thiosulfate, sodium oxalate, and sodium peroxide.

4. A method for enriching manganese from low-grade manganese carbonate ore according to any one of claims 1 to 3, characterized in that: The low-grade manganese carbonate ore and the sodium salt are mixed according to the following mass ratio relationship: 0.01≤(Mn+Fe+Al+Si) / Na≤6.

28.

5. The method for enriching manganese from low-grade manganese carbonate ore according to any one of claims 1 to 3, characterized in that: The low-grade manganese carbonate ore is ground to a particle size that satisfies a particle size of less than 200 meshes, and the mass percentage of the particle size is not less than 95%.

6. A method for enriching manganese from low-grade manganese carbonate ore according to any one of claims 1 to 3, characterized in that: The calcination conditions are as follows: the calcination temperature is 300-1000° C., the calcination atmosphere is an oxidizing atmosphere, a neutral atmosphere or a weakly reducing atmosphere, and the calcination time is 5-120 minutes.

7. The method for enriching manganese from low-grade manganese carbonate ore according to claim 6, characterized in that: The oxidizing atmosphere is an atmosphere in which the volume content of oxygen does not exceed 58%; The neutral atmosphere is a nitrogen atmosphere or an inert atmosphere; The weak reducing atmosphere is an atmosphere in which the volume content of reducing gas is lower than 2.63%.

8. A method for enriching manganese from low-grade manganese carbonate ore according to any one of claims 1 to 4, characterized in that: The roasted material is ground to a particle size that satisfies a particle size of less than 300 meshes, and the mass percentage thereof reaches 100%.

9. The method for enriching manganese from low-grade manganese carbonate ore according to claim 1, characterized in that: The magnetic field strength used in the magnetic separation is 100 to 5000 Gs.

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