Process for the recovery of manganese by suspension roasting of manganese nodules

Abstract

The present application belongs to the technical field of mineral processing, and particularly relates to a method for recovering manganese by suspending roasting of manganese nodule. The manganese nodule is crushed and magnetically separated, and then reduced and roasted, so that the strong magnetic mineral in the finely ground product is separated, and manganese concentrate is obtained. The present application has the characteristics of simple process equipment, low processing cost, small environmental pollution, low investment and operation cost, and high manganese recovery rate. The roasting product of the intermediate product can be used as a raw material for smelting manganese-iron alloy, and the final product manganese concentrate can be used as a raw material for smelting metallic manganese.

Description

Technical Field

[0001] This invention belongs to the field of mineral processing technology, and specifically relates to a method for recovering manganese by suspension roasting of manganese nodules. Background Technology

[0002] Manganese nodules, also known as polymetallic nodules, are core-shaped rocks composed of a shell of iron and manganese hydroxides surrounding a core, containing various valuable elements. Deep-sea manganese nodules are widely distributed at depths of 4000-6000 meters. Approximately 4400 tons of manganese nodules are found per square kilometer of the deep seabed, with total seabed reserves estimated at 3-3.5 trillion tons. The Pacific Ocean alone holds 1.7 trillion tons of manganese nodules, and they are growing at a rate of approximately 10-16 million tons per year. Manganese nodules contain 17.4%-28.07% manganese and also have a relatively high iron content. China is a major consumer of both manganese and iron products, but due to a prevalence of low-grade manganese and iron ore and a severe shortage of high-grade ore, the development and utilization of manganese nodules has significant theoretical and practical implications.

[0003] Manganese nodules are a difficult-to-process mineral resource. Manganese mainly exists in the form of δ-MnO2, with a stable crystal structure. It is sparingly soluble in acidic and alkaline solutions, and generally requires the removal of manganese from the mineral. 4+ Reduce to Mn 2+ Subsequent leaching. Currently, commonly used reduction methods include pyrometallurgical reduction, hydrometallurgical reduction, and biological reduction. Although hydrometallurgical reduction for manganese leaching is mild and energy-efficient, the waste liquid produced has an adverse impact on the environment. While biological reduction overcomes some of the shortcomings of hydrometallurgical reduction, it still suffers from a long cycle. Conventional pyrometallurgical reduction not only involves many steps and high energy consumption but also produces a large amount of polluting gases. In contrast, the suspension roasting process adopted in this invention features a simplified process, low energy consumption, and ultra-low emissions. Summary of the Invention

[0004] The purpose of this invention is to provide a method for recovering manganese from manganese nodules by suspension roasting. By crushing and magnetically separating the manganese nodules, followed by reduction roasting, the process is simplified. This invention features simple equipment, low processing cost, minimal environmental pollution, low investment and operating costs, and high manganese recovery rate.

[0005] A method for recovering manganese from manganese nodules by suspension roasting comprises the following steps:

[0006] Step 1: Crush the manganese nodules to -5mm, then pulverize them until the portion with a particle size of -1mm accounts for more than 95% of the total weight, and then grind them until the portion with a particle size of -0.074mm accounts for more than 80% of the total weight, to produce powder ore;

[0007] Step 2: Perform a first-stage strong magnetic separation on the powdered ore to obtain a first-stage strong magnetic separation concentrate and a first-stage strong magnetic separation tailings. Perform a second-stage strong magnetic separation on the first-stage strong magnetic separation concentrate to obtain a second-stage strong magnetic separation concentrate and a second-stage strong magnetic separation tailings. Then perform a third-stage strong magnetic separation on the second-stage strong magnetic separation concentrate to obtain a third-stage strong magnetic separation concentrate and a third-stage strong magnetic separation tailings.

[0008] Step 3: Place the three-stage strong magnetic separation concentrate in a vertical tubular roasting furnace, set the roasting temperature to 550-650℃, introduce nitrogen to replace the air in the tubular roasting furnace and preheat for 8-10 minutes, then introduce reducing gas to keep the strong magnetic separation concentrate in a suspended state and perform reduction roasting on the strong magnetic separation concentrate. After roasting for 30 minutes, stop the reducing gas and continue to introduce N2 for protective cooling for 20 minutes, then quench with water, filter and dry to obtain the roasted product.

[0009] Step 4: Grind the roasted product until -0.038mm accounts for more than 90% of the total weight to obtain a finely ground product;

[0010] Step 5: Perform weak magnetic separation on the finely ground product to separate the strongly magnetic minerals from the finely ground product, thus obtaining manganese concentrate.

[0011] Furthermore, the main component of the manganese nodules described in step 1 is MnO2, containing 19%-21% Mn and 11%-13% SiO2 by mass percentage.

[0012] Furthermore, the magnetic field strength of the first-stage strong magnetic separation in step 2 is 8000-12000 Gs, the magnetic field strength of the second-stage strong magnetic separation is 6000-7000 Gs, and the magnetic field strength of the third-stage strong magnetic separation is 4000-5000 Gs.

[0013] Furthermore, the reducing gas mentioned in step 3 is a mixture of CO, H2, and N2 simulating natural gas cracking gas, with a gas flow ratio of CO, H2, and N2 of 1:3:6. The total gas flow rate is 550-650 mL / min of reducing gas per 30g of strong magnetic separation concentrate, and the gas is introduced in the order of N2-CO-H2.

[0014] Furthermore, the manganese concentrate described in step 5 has a grade of 30%-31% and a manganese recovery rate of 93%-94%.

[0015] The beneficial effects of this invention are:

[0016] The suspension roasting process adopted in this invention has the characteristics of simplified process, low energy consumption, ultra-low emissions, simple process equipment, low processing cost, low environmental pollution, low investment and operating cost, high manganese recovery rate, intermediate product roasting product can be used as raw material for smelting ferromanganese alloy, and final product manganese concentrate can be used as raw material for smelting metallic manganese, which is of great significance for the development and utilization of manganese nodules. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the process for recovering manganese by suspension roasting of manganese nodules according to the present invention. Detailed Implementation

[0018] The manganese nodules used in this embodiment of the invention have a particle size of 5-10 mm.

[0019] The high-intensity magnetic separator used in this embodiment of the invention is a vertical ring high-gradient high-intensity magnetic separator.

[0020] The reducing gas used in the embodiments of the present invention is a commercially available product well known to those skilled in the art.

[0021] The intermediate roasted product obtained by the method provided by this invention can be used as a raw material for smelting ferromanganese alloy, and the final product, manganese concentrate, can be used as a raw material for smelting metallic manganese.

[0022] A schematic diagram of the process for recovering manganese from manganese nodules by suspension roasting in an embodiment of the present invention is shown below. Figure 1 As shown.

[0023] Example 1

[0024] A method for recovering manganese from manganese nodules by suspension roasting includes the following steps:

[0025] Manganese nodules are crushed to -5mm using a jaw crusher, then pulverized to 100% of the total weight using a disc mill, and finally ground to more than 80% of the total weight of the particles with a size of -0.074mm, thus producing fine ore.

[0026] Take 5 kg of fine ore and perform a first-stage strong magnetic separation with a magnetic field strength of 8000 Gs to obtain a first-stage strong magnetic separation concentrate and a first-stage strong magnetic separation tailings. Then, perform a second-stage strong magnetic separation with a magnetic field strength of 6000 Gs to obtain a second-stage strong magnetic separation concentrate and a second-stage strong magnetic separation tailings. Finally, perform a third-stage strong magnetic separation with a magnetic field strength of 5000 Gs to obtain a third-stage strong magnetic separation concentrate and a third-stage strong magnetic separation tailings.

[0027] Take 30g of the third-stage strong magnetic separation concentrate and place it in a vertical tubular roasting furnace. Set the roasting temperature to 550℃. After replacing the air in the tubular roasting furnace with nitrogen and preheating for 10min, introduce N2 gas at a rate of 360mL / min, CO gas at a rate of 60mL / min, and H2 gas at a rate of 180mL / min in sequence to keep the strong magnetic separation concentrate in a suspended state. Perform reduction roasting on the strong magnetic separation concentrate. After roasting for 30min, stop the reduction gas and continue to introduce N2 for protective cooling for 20min. Then quench with water, filter and dry to obtain the roasted product.

[0028] The roasted product is ground through a three-roll four-cylinder rod mill to a particle size of -0.038mm, which accounts for more than 90% of the total weight, to obtain a finely ground product.

[0029] The finely ground product is subjected to weak magnetic separation through a magnetic separator to separate the strongly magnetic minerals from the finely ground product, thus obtaining manganese concentrate;

[0030] The manganese concentrate has an Mn grade of 30.14% and an Mn recovery rate of 93.34%.

[0031] Example 2

[0032] A method for recovering manganese from manganese nodules by suspension roasting includes the following steps:

[0033] Manganese nodules are crushed to -5mm using a jaw crusher, then pulverized to 100% of the total weight using a disc mill, and finally ground to more than 80% of the total weight of the particles with a size of -0.074mm, thus producing fine ore.

[0034] Take 5 kg of fine ore and perform a first-stage strong magnetic separation with a magnetic field strength of 8000 Gs to obtain a first-stage strong magnetic separation concentrate and a first-stage strong magnetic separation tailings. Then, perform a second-stage strong magnetic separation with a magnetic field strength of 6000 Gs to obtain a second-stage strong magnetic separation concentrate and a second-stage strong magnetic separation tailings. Finally, perform a third-stage strong magnetic separation with a magnetic field strength of 5000 Gs to obtain a third-stage strong magnetic separation concentrate and a third-stage strong magnetic separation tailings.

[0035] Take 30g of the third-stage strong magnetic separation concentrate and place it in a vertical tubular roasting furnace. Set the roasting temperature to 650℃. After replacing the air in the tubular roasting furnace with nitrogen and preheating for 10min, introduce N2 gas at a rate of 360mL / min, CO gas at a rate of 60mL / min, and H2 gas at a rate of 180mL / min in sequence to keep the strong magnetic separation concentrate in a suspended state. Perform reduction roasting on the strong magnetic separation concentrate. After roasting for 30min, stop the reduction gas and continue to introduce N2 for protective cooling for 20min. Then quench with water, filter and dry to obtain the roasted product.

[0036] The roasted product is ground through a three-roll four-cylinder rod mill to a particle size of -0.038mm, which accounts for more than 90% of the total weight, to obtain a finely ground product.

[0037] The finely ground product is subjected to weak magnetic separation through a magnetic separator to separate the strongly magnetic minerals from the finely ground product, thus obtaining manganese concentrate;

[0038] The manganese concentrate has an Mn grade of 30.70% and an Mn recovery rate of 93.58%.

[0039] Example 3

[0040] A method for recovering manganese from manganese nodules by suspension roasting includes the following steps:

[0041] Manganese nodules are crushed to -5mm using a jaw crusher, then pulverized to 100% of the total weight using a disc mill, and finally ground to more than 80% of the total weight of the particles with a size of -0.074mm, thus producing fine ore.

[0042] Take 5 kg of fine ore and perform a first-stage strong magnetic separation with a magnetic field strength of 10000 Gs to obtain a first-stage strong magnetic separation concentrate and a first-stage strong magnetic separation tailings. Then, perform a second-stage strong magnetic separation on the first-stage strong magnetic separation concentrate with a magnetic field strength of 6500 Gs to obtain a second-stage strong magnetic separation concentrate and a second-stage strong magnetic separation tailings. Finally, perform a third-stage strong magnetic separation on the second-stage strong magnetic separation concentrate with a magnetic field strength of 4500 Gs to obtain a third-stage strong magnetic separation concentrate and a third-stage strong magnetic separation tailings.

[0043] Take 30g of the third-stage strong magnetic separation concentrate and place it in a vertical tubular roasting furnace. Set the roasting temperature to 600℃. After replacing the air in the tubular roasting furnace with nitrogen and preheating for 8 minutes, introduce N2 gas at a rate of 330mL / min, CO gas at a rate of 55mL / min, and H2 gas at a rate of 165mL / min in sequence to keep the strong magnetic separation concentrate in a suspended state. Perform reduction roasting on the strong magnetic separation concentrate. After roasting for 30 minutes, stop the reduction gas and continue to introduce N2 for protective cooling for 20 minutes. Then, quench with water, filter and dry to obtain the roasted product.

[0044] The roasted product is ground through a three-roll four-cylinder rod mill to a particle size of -0.038mm, which accounts for more than 90% of the total weight, to obtain a finely ground product.

[0045] The finely ground product is subjected to weak magnetic separation through a magnetic separator to separate the strongly magnetic minerals from the finely ground product, thus obtaining manganese concentrate;

[0046] The manganese concentrate has an Mn grade of 30.35% and an Mn recovery rate of 94.49%.

[0047] Example 4

[0048] A method for recovering manganese from manganese nodules by suspension roasting includes the following steps:

[0049] Manganese nodules are crushed to -5mm using a jaw crusher, then pulverized to 100% of the total weight using a disc mill, and finally ground to more than 80% of the total weight of the particles with a size of -0.074mm, thus producing fine ore.

[0050] Take 5 kg of fine ore and perform a first-stage strong magnetic separation at a magnetic field strength of 12000 Gs to obtain a first-stage strong magnetic separation concentrate and a first-stage strong magnetic separation tailings. Then, perform a second-stage strong magnetic separation on the first-stage strong magnetic separation concentrate at a magnetic field strength of 6500 Gs to obtain a second-stage strong magnetic separation concentrate and a second-stage strong magnetic separation tailings. Finally, perform a third-stage strong magnetic separation on the second-stage strong magnetic separation concentrate at a magnetic field strength of 4000 Gs to obtain a third-stage strong magnetic separation concentrate and a third-stage strong magnetic separation tailings.

[0051] Take 30g of the third-stage strong magnetic separation concentrate and place it in a vertical tubular roasting furnace. Set the roasting temperature to 550℃. After replacing the air in the tubular roasting furnace with nitrogen and preheating for 9 minutes, introduce N2 gas at a rate of 390mL / min, CO gas at a rate of 65mL / min, and H2 gas at a rate of 195mL / min in sequence to keep the strong magnetic separation concentrate in a suspended state. Perform reduction roasting on the strong magnetic separation concentrate. After roasting for 30 minutes, stop the reduction gas and continue to introduce N2 for protective cooling for 20 minutes. Then, quench with water, filter and dry to obtain the roasted product.

[0052] The roasted product is ground through a three-roll four-cylinder rod mill to a particle size of -0.038mm, which accounts for more than 90% of the total weight, to obtain a finely ground product.

[0053] The finely ground product is subjected to weak magnetic separation through a magnetic separator to separate the strongly magnetic minerals from the finely ground product, thus obtaining manganese concentrate;

[0054] The manganese concentrate has an Mn grade of 30.00% and an Mn recovery rate of 93.92%.

[0055] Example 5

[0056] A method for recovering manganese from manganese nodules by suspension roasting includes the following steps:

[0057] Manganese nodules are crushed to -5mm using a jaw crusher, then pulverized to 100% of the total weight using a disc mill, and finally ground to more than 80% of the total weight of the particles with a size of -0.074mm, thus producing fine ore.

[0058] Take 5 kg of fine ore and perform a first-stage strong magnetic separation at a magnetic field strength of 12000 Gs to obtain a first-stage strong magnetic separation concentrate and a first-stage strong magnetic separation tailings. Then, perform a second-stage strong magnetic separation on the first-stage strong magnetic separation concentrate at a magnetic field strength of 7000 Gs to obtain a second-stage strong magnetic separation concentrate and a second-stage strong magnetic separation tailings. Finally, perform a third-stage strong magnetic separation on the second-stage strong magnetic separation concentrate at a magnetic field strength of 4500 Gs to obtain a third-stage strong magnetic separation concentrate and a third-stage strong magnetic separation tailings.

[0059] Take 30g of the third-stage strong magnetic separation concentrate and place it in a vertical tubular roasting furnace. Set the roasting temperature to 650℃. After replacing the air in the tubular roasting furnace with nitrogen and preheating for 8 minutes, introduce N2 gas at a rate of 360mL / min, CO gas at a rate of 60mL / min, and H2 gas at a rate of 180mL / min in sequence to keep the strong magnetic separation concentrate in a suspended state. Perform reduction roasting on the strong magnetic separation concentrate. After roasting for 30 minutes, stop the reduction gas and continue to introduce N2 for protective cooling for 20 minutes. Then, quench with water, filter and dry to obtain the roasted product.

[0060] The roasted product is ground through a three-roll four-cylinder rod mill to a particle size of -0.038mm, which accounts for more than 90% of the total weight, to obtain a finely ground product.

[0061] The finely ground product is subjected to weak magnetic separation through a magnetic separator to separate the strongly magnetic minerals from the finely ground product, thus obtaining manganese concentrate;

[0062] The manganese concentrate has an Mn grade of 31.00% and an Mn recovery rate of 94.33%.

Claims

1. A process for the recovery of manganese by suspension roasting of manganese nodules, characterised in that, The following steps are carried out: Step 1, the manganese nodule is crushed to -5mm, then pulverized to a particle size of -1mm, and the portion of -1mm accounts for more than 95% of the total weight, and then ground to a particle size of -0.074mm, and the portion of -0.074mm accounts for more than 80% of the total weight, to form a powder ore; the manganese nodule mainly contains MnO2, and contains Mn 19%-21% and SiO211%-13% by mass percentage; Step 2, the powder ore is subjected to one-stage high-intensity magnetic separation to obtain one-stage high-intensity magnetic separation concentrate and one-stage high-intensity magnetic separation tailings, the one-stage high-intensity magnetic separation concentrate is subjected to two-stage high-intensity magnetic separation to obtain two-stage high-intensity magnetic separation concentrate and two-stage high-intensity magnetic separation tailings, and the two-stage high-intensity magnetic separation concentrate is subjected to three-stage high-intensity magnetic separation to obtain three-stage high-intensity magnetic separation concentrate and three-stage high-intensity magnetic separation tailings; the magnetic field strength of the one-stage high-intensity magnetic separation is 8000-12000Gs, the magnetic field strength of the two-stage high-intensity magnetic separation is 6000-7000Gs, and the magnetic field strength of the three-stage high-intensity magnetic separation is 4000-5000Gs; Step 3, the three-stage high-intensity magnetic separation concentrate is placed in a vertical tube roasting furnace, the roasting temperature is set to 550-650℃, N2 is introduced to replace the air in the vertical tube roasting furnace and preheated for 8-10min, then reducing gas is introduced to make the three-stage high-intensity magnetic separation concentrate in a suspended state, the three-stage high-intensity magnetic separation concentrate is subjected to reduction roasting, after reduction roasting for 30min, the introduction of reducing gas is stopped, N2 is continuously introduced for protection cooling for 20min, then water quenching is carried out, and after filtration and drying, a roasting product is obtained; Step 4, the roasting product is ground to a particle size of -0.038mm, and the portion of -0.038mm accounts for more than 90% of the total weight, to obtain a finely ground product; Step 5, the finely ground product is subjected to weak magnetic separation to separate the strongly magnetic minerals in the finely ground product, i.e. to obtain a manganese concentrate.

2. The process for the recovery of manganese by suspension roasting of manganese nodules according to claim 1, characterized in that, The reducing gas in step 3 is a mixed gas of CO, H2 and N2 simulating natural gas cracking gas, the gas flow ratio of CO, H2 and N2 is 1:3:6, and the total gas flow is 550-650mL / min per 30g of three-stage high-intensity magnetic separation concentrate, and the gas introduction sequence is N2-CO-H2.

3. The process for the recovery of manganese by suspension roasting of manganese nodules according to claim 1, characterized in that, The manganese concentrate in step 5 has a Mn grade of 30%-31% and a manganese recovery rate of 93%-94%.

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