Method for extracting valuable metal from deep sea polymetallic nodule through chloridizing roasting

Abstract

The invention belongs to the technical field of marine mineral resource development, and relates to a method for extracting valuable metals from deep-sea polymetallic nodules through chloridizing roasting. According to the method, the deep-sea polymetallic nodule and the chlorinating agent are mixed according to a specific proportion and then roasted, so that valuable metals such as manganese, nickel, cobalt and copper in the manganese nodule are converted into soluble chlorides, and then a water leaching process is adopted, so that efficient extraction of various valuable metals in the deep-sea polymetallic nodule is realized; the technology which is low in roasting temperature, high in chlorinating agent utilization rate, high in metal leaching rate, short in process and low in pollution emission is obtained, and the technology has important economic and social benefits of promoting green development of deep sea resources and relieving strategic metal supply and demand contradiction.

Description

Technical Field

[0001] This invention belongs to the field of marine mineral resource development technology, and relates to a method for extracting valuable metals by chlorination roasting of deep-sea polymetallic nodules. Background Technology

[0002] Deep-sea polymetallic nodules, rich in strategic metals such as manganese, copper, nickel, and cobalt, are abundant and widely distributed, and are considered an important alternative resource to alleviate the depletion of terrestrial resources and ensure the security of the global metal supply chain. With the acceleration of global industrialization, the demand for metals such as nickel and cobalt is surging in fields such as new energy and high-end manufacturing. However, the mining of traditional terrestrial minerals not only faces reserve limitations but also suffers from high energy consumption and pollution, making it difficult to meet the needs of sustainable development. Therefore, the development and utilization of deep-sea polymetallic nodules has become a focus of international attention.

[0003] However, polymetallic nodules on the seabed generally exist in an amorphous or semi-crystalline state with poor crystallinity and low content of valence metal elements. Existing extraction technologies include pyrometallurgical and hydrometallurgical processes, but these currently suffer from bottlenecks such as low metal recovery rates, complex processes, high reagent consumption, and high environmental pollution risks, which restrict their large-scale development.

[0004] Therefore, developing an efficient, green, and economical process for extracting valuable metals from polymetallic nodules is of great practical significance for promoting the industrial utilization of deep-sea resources and ensuring the supply of strategic metals. Summary of the Invention

[0005] In view of the aforementioned technical problems, this invention proposes a method for extracting valuable metals from deep-sea polymetallic nodules through chlorination roasting. This invention involves mixing deep-sea polymetallic nodules with a chlorinating agent in a specific ratio and then roasting the mixture. This converts valuable metals such as manganese, nickel, cobalt, and copper in the manganese nodules into soluble chlorides. Subsequently, a water leaching process is employed to achieve efficient extraction of multiple valuable metals from deep-sea polymetallic nodules. This process achieves low roasting temperature, high chlorinating agent utilization rate, high metal leaching rate, short process flow, and low pollution emissions. It has significant economic and social benefits in promoting the green development of deep-sea resources and alleviating the supply and demand imbalance of strategic metals.

[0006] The present invention adopts the following technical solution.

[0007] A method for extracting valuable metals from deep-sea polymetallic nodules by chlorination roasting includes the following steps: Step 1: Air dry the deep-sea polymetallic nodules naturally, then crush and grind them to a certain particle size; Step 2: Mix the polymetallic nodules from Step 1 with ammonium chloride in a certain proportion and mix them evenly to obtain a mixture. Step 3: The mixture from Step 2 is calcined at high temperature to obtain calcined sand; Step 4: Stir and soak the calcined sand from Step 3 in water. After solid-liquid separation, leachate and leachate residue are obtained. Step 5: The gas generated during the roasting process in Step 3 is passed into a water tank for treatment to form the product; Step 6: Filter and dry the product formed in step 5 for further recycling.

[0008] Furthermore, in step 1, the polymetallic nodule minerals are ground to a particle size of 100 mesh, accounting for 70% of the total.

[0009] Furthermore, in step 2, the amount of ammonium chloride used is 70% to 150% of the mass of the polymetallic nodules.

[0010] Furthermore, in step 3, the high-temperature calcination equipment is a tube furnace.

[0011] Furthermore, in step 3, the roasting temperature is 300℃~500℃, and the roasting time is 2 hours.

[0012] Furthermore, in step 4, the water immersion process conditions are as follows: liquid-to-solid volume-to-mass ratio is 4~8:1, immersion temperature is 30℃~60℃, stirring speed is 250rpm~400rpm, and immersion time is 30min~120min.

[0013] Furthermore, in step 5, the product is ammonium chloride.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows.

[0015] 1. Solid-state roasting with ammonium chloride replaces wet strong acid leaching with a solid-state reaction, avoiding the corrosion of equipment and related maintenance costs caused by strong acids. Compared with traditional pyrometallurgical methods, the roasting temperature is lower, resulting in a significant reduction in energy consumption. It also eliminates the need for complex acid-base adjustments and wastewater treatment, reducing reagent consumption and costs, and making it easier to industrialize.

[0016] 2. Rational treatment of exhaust gas generated during the roasting process, achieving closed-loop circulation of hazardous gases and regeneration of ammonium chloride, thereby reducing the risk of environmental pollution.

[0017] 3. The roasted product has a loose texture, good water solubility, and is easy to break. It does not require grinding and can be directly soaked in water, reducing processing costs.

[0018] 4. The method described in this invention has the advantages of short process flow, easy control of conditions, high metal recovery rate, good iron inhibition effect, and the leaching rate of manganese, nickel and cobalt is above 99% throughout the process, the copper leaching rate is above 98%, and the iron leaching rate is below 1%. Detailed Implementation

[0019] The technical solutions of this invention will now be clearly and completely described. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0020] A method for extracting valuable metals from deep-sea polymetallic nodules by chlorination roasting includes the following steps: Step 1: Air dry the deep-sea polymetallic nodules naturally, then crush and grind them to a particle size of 100 mesh, accounting for 70% of the total. Step 2: Mix the polymetallic nodules from Step 1 with ammonium chloride in a certain proportion until homogeneous to obtain a mixture; the amount of ammonium chloride used is 70%~150% of the mass of the polymetallic nodules. Step 3: The mixture from Step 2 is subjected to high-temperature calcination. The high-temperature calcination equipment is a tube furnace, the calcination temperature is 300℃~500℃, and the calcination time is 2 hours to obtain calcined sand. Step 4: Stir and leach the calcined sand from Step 3. The leaching process conditions are as follows: liquid-to-solid volume-to-mass ratio of 4~8:1, leaching temperature of 30℃~60℃, stirring speed of 250rpm~400rpm, and leaching time of 30min~120min. After solid-liquid separation, leachate and leachate residue are obtained. Step 5: The gas generated during the roasting process in Step 3 is passed into a water tank for treatment to form ammonium chloride product; Step 6: Filter and dry the product formed in step 5 for further recycling.

[0021] Example 1.

[0022] 100 g of polymetallic nodule ore powder (mass fractions of main elements: Mn 27.64%, Ni 4.35%, Co 0.36%, Cu 2.53%, Fe 11.37%) was weighed and mixed evenly with 120 g of ammonium chloride. The mixture was then roasted in a tube furnace at 300 °C for 2 h. Part of the product adhering to the tube furnace was collected to obtain 170 g of roasted product (mass fractions of main elements: Mn 16.15%, Ni 2.53%, Co 0.21%, Cu 1.48%, Fe 6.68%), and 2 g of soot was collected. Then, 100 g of the roasted product was weighed and transferred to a beaker, water was added, and the liquid-solid ratio was 6:1. The mixture was stirred and leached at 50 °C and 300 rpm for 60 min. After leaching, the mixture was vacuum filtered to obtain 36 g of leaching residue and 700 mL of leaching solution. The flue gas is fed into a water tank for treatment, forming ammonium chloride, which is then filtered, dried, and solid ammonium chloride is obtained.

[0023] The mass percentages of the main elements in the leaching residue were Mn 0.454%, Ni 0.052%, Co 0.0046%, Cu 0.05%, and Fe 18.38%, respectively; the contents of the main elements in the leachate were Mn 22.92 g / L, Ni 3.59 g / L, Co 0.298 g / L, Cu 2.11 g / L, and Fe 0.156 g / L, respectively. The mass percentages of the main elements in the flue dust were Mn 2.09%, Ni 1.05%, Co 0.014%, Cu 0.95%, and Fe 0.65%, respectively. The leaching rates are shown in Table 1.

[0024] Table 1. Leaching rates of various elements in polymetallic nodules.

[0025] Example 2.

[0026] 100g of polymetallic nodule ore powder (mass fractions of main elements: Mn 27.64%, Ni 4.35%, Co 0.36%, Cu 2.53%, Fe 11.37%) was weighed and mixed evenly with 120g of ammonium chloride. The mixture was then roasted in a tube furnace at 400℃ for 2 hours. Part of the product adhering to the tube furnace was collected to obtain 160g of roasted product (mass fractions of main elements: Mn 17.17%, Ni 2.72%, Co 0.22%, Cu 1.58%, Fe 7.10%), and 1.5g of soot was collected. Then, 100g of the roasted product was weighed and transferred to a beaker, water was added, and the liquid-solid ratio was 6:1. The mixture was stirred and leached at 50℃ and 300 rpm for 60 minutes. After leaching, the mixture was vacuum filtered to obtain 37.3g of leaching residue and 740 mL of leaching solution. The flue gas is fed into a water tank for treatment, forming ammonium chloride, which is then filtered, dried, and solid ammonium chloride is obtained.

[0027] The mass percentages of the main elements in the leaching residue were Mn 0.142%, Ni 0.025%, Co 0.0031%, Cu 0.05%, and Fe 18.92%, respectively; the contents of the main elements in the leachate were Mn 23.19 g / L, Ni 3.65 g / L, Co 0.296 g / L, Cu 2.13 g / L, and Fe 0.092 g / L, respectively; and the mass percentages of the main elements in the flue dust were Mn 1.25%, Ni 1.04%, Co 0.013%, Cu 0.46%, and Fe 0.51%, respectively. The leaching rates are shown in Table 2.

[0028] Table 2. Leaching rates of various elements in polymetallic nodules.

[0029] Comparative Example 1: Hydrochloric acid roasting.

[0030] 100 g of polymetallic nodule ore powder (mass fractions of main elements: Mn 27.64%, Ni 4.35%, Co 0.36%, Cu 2.53%, Fe 11.37%) was weighed and mixed evenly with 120 g of hydrochloric acid. The mixture was then roasted in a tube furnace at 400℃ for 2 h. A portion of the product adhering to the tube furnace was collected to obtain 155 g of roasted product (mass fractions of main elements: Mn 17.83%, Ni 2.81%, Co 0.23%, Cu 1.63%, Fe 7.33%). 100 g of this product was then weighed and transferred to a beaker. Water was added, and the mixture was stirred and leached at 50℃ and 300 rpm for 60 min. After leaching, the mixture was vacuum filtered to obtain 56.5 g of leaching residue and 720 mL of leaching solution.

[0031] The mass percentages of the main elements in the leaching residue were Mn 20.32%, Ni 1.93%, Co 0.163%, Cu 1.26%, and Fe 9.58%. The contents of the main elements in the leachate were 10.23 g / L, 2.56 g / L, 0.205 g / L, 1.43 g / L, and 2.89 g / L, respectively. The leaching rates are shown in Table 3.

[0032] Table 3. Leaching rates of various elements in polymetallic nodules.

[0033] Through Examples 1, 2, and Comparative Example 1, it can be seen that the method of using ammonium chloride to reduce and roast deep-sea polymetallic nodules and extract their valuable metals significantly improves the leaching rate of valuable metals, while iron is effectively suppressed.

Claims

1. A method for extracting valuable metals from deep-sea polymetallic nodules through chlorination roasting, characterized in that, Includes the following steps: Step 1: Air dry the deep-sea polymetallic nodules naturally, then crush and grind them to a certain particle size; Step 2: Mix the polymetallic nodules from Step 1 with ammonium chloride in a certain proportion and mix them evenly to obtain a mixture. Step 3: The mixture from Step 2 is calcined at high temperature to obtain calcined sand; Step 4: Stir and soak the calcined sand from Step 3 in water. After solid-liquid separation, leachate and leachate residue are obtained. Step 5: The gas generated during the roasting process in Step 3 is passed into a water tank for treatment to form the product; Step 6: Filter and dry the product formed in step 5 for further recycling.

2. The method for extracting valuable metals from deep-sea polymetallic nodules by chlorination roasting according to claim 1, characterized in that, In step 1, the polymetallic nodule minerals are ground to a particle size of 100 mesh, accounting for 70%.

3. The method for extracting valuable metals from deep-sea polymetallic nodules by chlorination roasting according to claim 1, characterized in that, In step 2, the amount of ammonium chloride used is 70% to 150% of the mass of the polymetallic nodules.

4. The method for extracting valuable metals from deep-sea polymetallic nodules by chlorination roasting according to claim 1, characterized in that, In step 3, the high-temperature calcination equipment is a tube furnace.

5. The method for extracting valuable metals from deep-sea polymetallic nodules by chlorination roasting according to claim 1, characterized in that, In step 3, the roasting temperature is 300℃~500℃ and the roasting time is 2h.

6. The method for extracting valuable metals from deep-sea polymetallic nodules by chlorination roasting according to claim 1, characterized in that, In step 4, the water immersion process conditions are as follows: liquid-to-solid volume-to-mass ratio is 4~8:1, immersion temperature is 30℃~60℃, stirring speed is 250rpm~400rpm, and immersion time is 30min~120min.

7. The method for extracting valuable metals from deep-sea polymetallic nodules by chlorination roasting according to claim 1, characterized in that, In step 5, the product is ammonium chloride.

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