CN116813173A - Resource utilization method for submarine mining soil - Google Patents

Abstract

The invention discloses a method for utilizing seabed mining soil resources, and relates to the technical field of seabed mining. It includes the following steps: first, dehydrate the slurry collected from seabed mining so that the moisture content reaches 30 to 40%; classify and screen the bottom soil obtained by dehydration treatment to obtain the undersize; and then sieve the undersize. Carry out electrification treatment, and heavy metal cations can be obtained on the carbon rod positive electrode through the action of high-frequency current and low-frequency current; dehydrate the seabed soil after electrification treatment, mix the obtained soft mud with biomass powder, and add alkali After adding sexual additives and an appropriate amount of water, the reaction precursor is obtained; and then by using hydrothermal humification technology and thermochemical methods on the prepared reaction precursor, the heavy metal ions are finally fully recovered and the reaction product is used for soil improvement. And part of the output can be used to plant soil. The invention can realize resource utilization of deep sea mining soil.

Description

A method for utilizing seabed mining soil resources

Technical field

The invention relates to the technical field of seabed mining, and in particular to a method for utilizing seabed mining soil resources.

Background technique

There are abundant mineral resources at the bottom of the vast ocean. They have many types, large reserves, and high grades, and have huge development and utilization prospects. The development and utilization of seabed mineral resources has become a hot research topic at home and abroad. However, seabed mining inevitably brings a large amount of deep-sea sediments from the seabed. In engineering, deep-sea soil is usually dumped directly into the sea, causing plume disasters and environmental damage. However, the existing technology does not involve the treatment of deep sea sediments, so a method that can properly dispose of seabed mining sediments is urgently needed.

At the same time, deep-sea sediments are rich in organic matter and metal elements and have high recycling value. At present, the collected deep-sea soil cannot be effectively used and is discharged as garbage, resulting in a large amount of waste of resources. In addition, deep-sea mining soil contains large amounts of salt and heavy metals and cannot be directly used for crop cultivation. Therefore, adopting certain methods to process seabed mining soil and obtain usable resources such as heavy metals and planting soil can not only effectively reduce the environmental damage caused by seabed mining plumes, but also convert deep-sea mining soil into reusable resources, thereby obtaining ecological benefits. value and economic value.

Contents of the invention

The purpose of the present invention is to provide a method for utilization of seabed mining soil resources, which realizes the utilization of seabed mining soil by grading treatment, screening, electrification, hydrothermal humification and thermochemical methods. Resource utilization of mining soil.

In order to achieve the above objects, the present invention adopts the following technical solutions:

A method for utilizing seabed mining soil resources, including the following steps:

a. Dehydration: dehydrate the slurry collected from seabed mining so that its moisture content reaches 30 to 40%;

b. Screening, the bottom soil obtained by the dehydration treatment in step a is graded and screened to obtain the undersize, which is bottom soil rich in organic matter and a certain amount of heavy metals;

c. Electrify the under-sieve objects, put the under-sieve objects into a container filled with water, set high-frequency and low-frequency electrodes in the container, and destroy the under-sieve objects by passing high-frequency alternating current into the container. The chemical bond is used to enrich the heavy metal cations contained in the undersize material onto the positive electrode carbon rod by passing low-frequency direct current into the container, and collect the heavy metals on the positive electrode carbon rod;

d. Plate and frame filter press processing: put the bottom soil after electrification in step c into the plate and frame filter press for processing, and dehydrate the input organic materials to reduce their moisture content to 55 to 65 %;

e. Prepare a precursor mixture, mix the sludge obtained after step d with biomass powder, add alkaline additives and distilled water to it, and stir evenly to obtain a precursor mixture;

f. Reaction, placing the precursor mixture described in step e in a high-pressure reactor for reaction, centrifuging the resulting reaction product to obtain liquid product I and solid product I, wherein liquid product I is used as a liquid compound fertilizer;

g. After solid product I is digested with strong acid, centrifugal separation is performed to obtain liquid product II and solid product II. Solid product II is washed with deionized water to neutrality and vacuum dried to obtain hydrothermal biochar and can be used for planting. Soil;

h. Add a reducing agent to the liquid product II for reaction, and then undergo centrifugal separation to obtain the solid material which is the heavy metal.

The beneficial technical effects directly brought by the above technical solutions are:

By classifying and screening the slurry collected from seabed mining, the bottom soil rich in organic matter and a certain amount of heavy metals is screened out, and then the soil is electrified. Through the action of high-frequency current and low-frequency current, the carbon rod cathode can be Heavy metal cations are obtained from the energized seabed soil; then the seabed bottom soil after electrification treatment is dehydrated, the obtained soft mud is mixed with biomass powder, and after adding alkaline additives and an appropriate amount of water, the reaction precursor is obtained; the reaction precursor diagram is Place it in a high-pressure reactor for hydrothermal reaction, and then centrifuge the product. The liquid product I obtained can be used as a liquid compound fertilizer. Finally, the solid product I is processed to finally obtain hydrothermal biochar and soil that can be used for planting. .

From the perspective of raw materials, biomass powder can be easily obtained from seaweed and animal and plant corpses in the ocean. In addition, combined with the above steps, liquid compound fertilizer, hydrothermal biochar and soil that can be used for planting can be obtained. Therefore, the above technical solution as a whole can realize the resource utilization of seabed mining soil.

In the above-mentioned seabed mining soil resource utilization method, in step a, the slurry collected from seabed mining is lifted to the mother ship through a riser, and dewatered through a dewatering vibrating screen.

In the above-mentioned seabed mining soil resource utilization method, in step b, the bottom soil obtained after dehydration is subjected to a three-level screening process, wherein the first-level vibrating screen selected in the first-level screening process is a 10-mesh screen. The second-level vibrating screen selected in the secondary screening process is a 100-mesh screen, and the third-level vibrating screen selected in the third-level screening process is a 200-mesh screen.

In the above-mentioned seabed mining soil resource utilization method, in step b, the heavy metals contained in the undersize are metal ions of Cr, Cd, Ga, Cu, Ni, Co, Pb, Zn, Mn and Fe.

In the above-mentioned seabed mining soil resource utilization method, in step e, the preparation method of the biomass powder is: cleaning the biomass raw materials and removing impurities, then drying them, and grinding them into powder; The powdery biomass raw material is screened to retain the biomass powder that meets the requirements. After being dried and removed from the water in sequence, a biomass powder with a particle size of 100 to 200 mesh is obtained; the biomass raw material is selected from seaweed. and/or carcasses of marine animals and plants.

In the above-mentioned seabed mining soil resource utilization method, the alkaline additive is one or more of NaOH, KOH, CaO and Ca(OH) ₂ , Na ₂ CO ₃ and Na ₅ P ₃ O ₁₀ A mixture, in which the mass ratio of CaO and Ca(OH) ₂ to Na ₂ CO ₃ and Na ₅ P ₃ O ₁₀ is 1:1; the mass ratio of ooze, biomass powder, alkaline additives and distilled water is 1 ~50:0.3~5:0.25~2:0.1~30.

In the above-mentioned seabed mining soil resource utilization method, in step f, sufficient water is added to the high-pressure reactor to ensure the progress of the hydrothermal reaction. The temperature of the hydrothermal reaction is 180-200°C, and the pressure of the hydrothermal reaction is 1.5~5MPa, hydrothermal reaction time 20~28h.

In the above-mentioned seabed mining soil resource utilization method, in step g, the strong acid is a mixed acid obtained by mixing aqua regia with 70% mass fraction of perchloric acid and 30% mass fraction of concentrated nitric acid; or, Mixed acid is obtained by mixing water with 65% nitric acid, 25% sulfuric acid, and 10% hydrochloric acid; or aqua regia, 95% sulfuric acid, and 5% hydrogen. Mixed acid obtained by mixing hydrofluoric acid; or mixed acid obtained by mixing aqua regia with concentrated nitric acid with a mass fraction of 70% and concentrated hydrochloric acid with a mass fraction of 30%; the speed of centrifugal separation is 4000~12000r/min, and the centrifugation time is 15~ 30min; the temperature of vacuum drying is 70~80℃, and the time of vacuum drying is 20~24h; after vacuum drying, a 10-mesh screen is used for screening. After screening, the top part of the screen is hydrothermal biochar, and the bottom part is usable biochar. to the planting soil.

In the above-mentioned seabed mining soil resource utilization method, in step h, the reducing agent is one of sodium sulfite, sodium bisulfite, sodium nitrite, ferrous sulfate, potassium borohydride, sodium cyanoborohydride or sodium borohydride. One or more species; the mass ratio of the reducing agent to the volume of the liquid product II is 0.5 to 20 g: 20 to 100 mL, and the reaction time of adding the reducing agent is 3 to 24 hours.

In the above-mentioned seabed mining soil resource utilization method, all steps are completed on the mother ship; the liquid compound fertilizer is rich in phosphorus and humus, and the soluble phosphorus accounts for 45% to 65%, and the humus content is 0.01% ~0.03%.

Compared with the existing technology, the present invention brings the following beneficial technical effects:

(1) The present invention provides a method for utilizing seabed mining soil resources to effectively treat deep sea mining tailings. Compared with the existing method tilted into the sea, its resource utilization avoids plume disasters caused by direct emissions. It can be used as a measure to prevent and control plume disasters and avoid the impact of plumes caused by seabed mining on the marine ecological environment. the damage caused.

(2) The present invention provides a method for utilizing seabed mining soil resources. By classifying the deep sea mining soil lifted by the riser to the mother ship, the organic matter and inorganic matter in the seabed mining soil are effectively separated and the impact on the seabed is reduced. The difficulty of processing mining soil resources; through screening methods, polymetallic nodules from seabed mining are collected, and inorganic substances of different particle sizes, mainly sand, are obtained as building materials for marine engineering construction. Through electrification and hydrothermal humification Using a method combined with thermochemistry, liquid compound fertilizer was obtained, hydrothermal biochar was prepared, heavy metal ions in deep-sea mining soil were effectively collected, and the remaining soil from the reaction was finally collected, which can be used for planting and realizing seabed mining. The reduction, stabilization and harmlessness of soil have enabled the resource utilization of deep sea mining soil.

(3) A method for utilizing seabed mining soil resources provided by the present invention. The seabed mining soil composition contains a large amount of biological fragments, and biomass powder is added. The mixture is rich in a large amount of organic matter and trace elements required for plant growth. It has good fertility and is suitable for the growth and development of plants. After a series of treatments, it contains less heavy metal ions, which avoids contamination of the soil or enrichment of heavy metals in crops and harmful effects on the human body after being used for planting crops. Cause harm, the added sodium tripolyphosphate can reduce the salt content in the soil as an alkaline additive, and can also serve as an external phosphorus source; the fulvic acid and humic acid formed by humus can reduce the insolubility of the mixture. The phosphorus source is etched, thereby activating it to a certain extent, so that as much phosphorus element as possible is dissolved into the liquid compound fertilizer, which can be used to replenish the effective phosphorus content of the soil, promote plant growth, and can be used to improve soil and improve soil quality. Economic benefits.

(4) The present invention provides a method for utilization of seabed mining soil resources, in which the biomass material is made of seaweed, marine animals and plants, the raw materials are cheap and easy to obtain at sea, and the method is simple and can be operated on the mother ship, greatly Reduces the cost of seabed mining land resources;

(5) Marine animal carcasses are rich in fats and protein substances as well as slight humus. Algae and marine plants are rich in cellulose, protein and sugar. This embodiment adopts a new hydrothermal humification technology, which can remove fats. The substances are recombined and combined with cellulose, protein and small molecule sugar substances to synthesize artificial humus. As a kind of easily decayed floating garbage, the present invention salvages and utilizes the carcasses of marine animals and plants, realizing the transformation of garbage. Turning waste into treasure can also protect the marine ecological environment to a certain extent.

(6) The present invention provides a method for utilization of seabed mining soil resources. Polymetallic nodules are obtained through screening, and the sieved residue is energized so that most of the metal ions are concentrated on the carbon rods, and the A reducing agent is added to the reaction product to finely recover the remaining few metal ions. Compared with existing deep-sea mining that only collects nodules, the collection rate of seabed minerals is greatly improved and the economic benefits are improved.

Description of the drawings

The present invention will be further described below in conjunction with the accompanying drawings:

Figure 1 is a process flow chart of the utilization of seabed mining soil resources according to the present invention.

Detailed ways

The present invention proposes a method for utilizing seabed mining soil resources. In order to make the advantages and technical solutions of the present invention clearer, the present invention will be further described below with reference to specific examples.

The raw materials mentioned in the present invention can be purchased through commercial channels.

The structure and working principle of the plate and frame filter press, first-level vibrating screen, second-level vibrating screen, and third-level vibrating screen mentioned in the present invention can be realized by drawing on the existing technology.

The "strong acid" mentioned in the present invention is aqua regia, a mixed acid of 70% mass fraction of perchloric acid and 30% mass fraction of concentrated nitric acid, 65% mass fraction of nitric acid, 25% mass fraction of sulfuric acid and 10% mass fraction of sulfuric acid. % hydrochloric acid mixed acid, a mass fraction of 95% sulfuric acid and a mass fraction of 5% hydrofluoric acid, or a mass fraction of 70% concentrated nitric acid and a mass fraction of 30% concentrated hydrochloric acid.

The reducing agent mentioned in the present invention is sodium sulfite, sodium bisulfite, sodium nitrite, ferrous sulfate, potassium borohydride, sodium cyanoborohydride or sodium borohydride.

The alkaline auxiliary mentioned in the present invention is one or a mixture of several of NaOH, KOH, CaO, Ca(OH) ₂ , Na ₂ CO ₃ and Na ₅ P ₃ O ₁₀ ; The mass ratio of CaO and Ca(OH) ₂ to Na ₂ CO ₃ and Na ₅ P ₃ O ₁₀ in the mixture is 1:1.

The "high-pressure reactor" mentioned in the present invention is made of 1Cr18Ni9Ti stainless steel.

The "biomass raw material" mentioned in the present invention mainly refers to marine biomass, such as seaweed, marine animal and plant carcasses. After grinding the seaweed and/or marine animal and plant carcasses, the biomass powder is obtained by screening.

All methods described in the present invention can be completed on the mother ship, such as the first-level vibrating screen, the second-level vibrating screen, the third-level vibrating screen, the plate and frame filter press, the high-pressure reaction kettle, and the centrifugal device required in the method. etc., can be placed on the mother ship.

The main technical concept of the present invention is to use practical methods to utilize the resources of seabed mining soil, and to convert cheap and easily available marine pollutants into products with valuable resources as much as possible, that is, from low added value to high added value. Product transformation, and the method used is simple and easy to operate.

Specifically, the present invention, a method for utilizing seabed mining soil resources, includes the following steps:

Step 1. Dehydration: Dehydrate the slurry collected from seabed mining and use a dehydration vibrating screen to dehydrate it to a moisture content of 30 to 40%;

Step 2: Screening, the bottom soil obtained by dehydration treatment is graded and screened to obtain the undersize. The undersize is bottom soil rich in organic matter and a certain amount of heavy metals; first, a first-level vibrating screen is used. For screening, the first-level vibrating screen is a 10-mesh screen. After screening, the objects on the first-level vibrating screen are polymetallic nodules and a small amount of large-particle size inorganic matter; the second-level vibrating screen selected in the second-level screening process is 100 mesh screen, the third-level vibrating screen selected in the third-level screening process is a 200-mesh screen, the objects on the second-level vibrating screen and the third-level vibrating screen are inorganic substances of different particle sizes, mainly sand, which can be used as a marine engineering Building materials, the final under-sieved material after three-stage screening is bottom soil rich in organic matter and a small amount of heavy metals. Among them, a small amount of heavy metals are Cr, Cd, Ga, Cu, Ni, Co, Pb, Zn, Mn and Fe;

Step 3: Electrify the objects under the sieve, put the objects under the sieve into a container filled with water, set high-frequency and low-frequency electrodes in the container, the positive and negative electrodes are carbon rods, pass the high-frequency into the container Alternating current is used to destroy the chemical bonds of the undersized objects, and low-frequency direct current is passed into the container to enrich the heavy metal cations contained in the undersized objects onto the positive carbon rod, and collect the heavy metals on the positive carbon rod;

Step 4: Plate and frame filter press processing. Put the electrified bottom soil into the plate and frame filter press for processing. The bottom soil has smaller particle size, contains a small amount of heavy metals and is rich in organic matter. It is processed through the plate and frame filter press. The filter press dehydrates the input organic materials and reduces the moisture content to 55% to 65%;

Step 5: Prepare a precursor mixture, mix the sludge obtained after step 4 with biomass powder, add alkaline additives and distilled water to it, stir evenly to obtain a precursor mixture; wherein, the biomass powder is seaweed and/or Made from the carcasses of marine animals and plants, the mass ratio of ooze to biomass powder, alkaline additives and distilled water is 1 to 50: 0.3 to 5: 0.25 to 2: 0.1 to 30;

The preparation method of biomass powder is: cleaning the biomass raw materials, removing impurities, drying, and grinding them into powder; screening the powdered biomass raw materials to retain the biomass powder that meets the requirements , and after sequential drying and removal of moisture, biomass powder with a particle size of 100 to 200 mesh is obtained; the biomass raw material is selected from seaweed and/or marine animal and plant corpses.

The alkaline auxiliary agent is one or a mixture of several of NaOH, KOH, CaO and Ca(OH) ₂ , Na ₂ CO ₃ and Na ₅ P ₃ O ₁₀ , where CaO, Ca(OH) ₂ and Na ₂ The mass ratio of CO ₃ and Na ₅ P ₃ O ₁₀ is 1:1;

Step 6: Reaction: Place the precursor mixture of Step 5 in a high-pressure reactor for reaction, and add enough water to the reaction volume to ensure that the hydrothermal reaction proceeds sufficiently. The temperature of the hydrothermal reaction is 180~200°C, the pressure of the hydrothermal reaction is 1.5~5MPa, and the time of the hydrothermal reaction is 20~28h; after the reaction is completed, cool the reaction kettle and reduce the pressure and open the reaction kettle; the obtained reaction product Carry out centrifugal separation to obtain liquid product I and solid product I. The liquid product I is used as a liquid compound fertilizer; the liquid compound fertilizer is rich in phosphorus and humus, and the soluble phosphorus accounts for 45% to 65%, and the humus content 0.01%～0.03%;

Step 7: After the solid product I is digested with strong acid, centrifugal separation is performed to obtain the liquid product II and the solid product II. The solid product II is washed with deionized water to neutrality and dried in a vacuum to obtain hydrothermal biochar and can be used. Planted soil; the centrifugal speed is 4000-12000r/min, and the centrifugation time is 15-30min; the vacuum drying temperature is 70-80°C, and the vacuum drying time is 20-24h; the vacuum drying The temperature is 70~80℃, and the vacuum drying time is 20~24h;

Step 8: Add a reducing agent to the liquid product II for reaction, and then undergo centrifugal separation to obtain the solid material which is the heavy metal.

The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application.

Example 1:

Step 1: Dehydrate the collected seabed mining soil through a dewatering vibrating screen to achieve a moisture content of 30%;

Step 2: Sieve the bottom soil obtained by dehydration treatment through a three-stage vibrating sieve, and collect the final undersize - bottom soil rich in organic matter and a small amount of heavy metals;

Step 3: Put the sieved objects into a container filled with water. At the same time, set a high-frequency electrode of 100kHz and a low-frequency electrode of 20kHz in the container. The positive and negative electrodes are carbon rods. First, 100kHz alternating current is passed to destroy the chemical bonds of the objects under the sieve, and then 20kHz direct current is passed to enrich the heavy metal cations onto the positive carbon rod. This process lasts for three minutes, and finally the heavy metals on the carbon rod are collected;

Step 4: Put the electrified bottom soil into a plate and frame filter press for processing. The bottom soil has small particle size, contains a small amount of heavy metals and is rich in organic matter. The input organic materials are dehydrated through a plate and frame filter press to reduce the moisture content rate to 55%;

Step 5. Mix the sludge dehydrated in step 4 with the biomass powder, then add the alkaline additive mixture of CaO, Ca(OH) ₂ , NaOH and Na ₅ P ₃ O ₁₀ and an appropriate amount of distilled water, and stir evenly. A precursor mixture is obtained. Among them, the mass ratio of soft mud, biomass powder, alkaline additive mixture and distilled water is 15:1.5:2:1; among them, the mass ratio of CaO, Ca(OH) ₂ , NaOH and Na ₅ P ₃ O ₁₀ is 1 :1.5.:1.5:1; Biomass powder preparation method: first process the biomass raw materials to remove impurities and moisture, dry them, use a pulverizer to grind the biomass raw materials into powder, sieve the powder, and remove For particles that do not meet the requirements, the powder is dried to remove moisture. The particle size of the biomass powder is 100 mesh;

Step 6: Place the precursor mixture in a high-pressure reactor, and add enough water to the reaction volume to ensure that the hydrothermal reaction proceeds adequately. Then the pressure of the high-pressure reaction kettle was raised to 1.5MPa, and the high-pressure reaction kettle was heated to 180°C. After 20 hours, cool the high-pressure reaction kettle and reduce the pressure before opening the high-pressure reaction kettle;

Step 7: Set the centrifugal speed to 4000r/min. After the reaction product is centrifuged for 15 minutes, liquid product I and solid product I are obtained. Among them, liquid product I can be used as a liquid compound fertilizer;

Step 8. After the solid product I is digested with a mixed acid of 30% mass fraction of concentrated nitric acid, 65% mass fraction of nitric acid, 25% mass fraction of sulfuric acid and 10% mass fraction of hydrochloric acid, the solid product I is centrifuged to obtain the solid product II and liquid product II. The solid product II is washed with deionized water until neutral and vacuum dried to obtain hydrothermal biochar and soil that can be used for planting;

Step 9: Add the reducing agent sodium sulfite to the liquid product II and react for 16 hours. The volume ratio of the mass of the reducing agent to the liquid product II is 0.55g:25mL. Then perform centrifugal separation to obtain heavy metal precipitation.

Example 2:

Step 1: Dehydrate the collected seabed mining soil through a dewatering vibrating screen to make the moisture content reach 40%;

Step 2: Sieve the bottom soil obtained by dehydration treatment through a three-stage vibrating sieve, and collect the final undersize - bottom soil rich in organic matter and a small amount of heavy metals;

Step 3: Put the sieved objects into a container filled with water. At the same time, set a high-frequency electrode of 100kHz and a low-frequency electrode of 20kHz in the container. The positive and negative electrodes are carbon rods. First, 100kHz alternating current is passed to destroy the chemical bonds of the objects under the sieve, and then 20kHz direct current is passed to enrich the heavy metal cations onto the positive carbon rod. This process lasts for three minutes, and finally the heavy metals on the carbon rod are collected;

Step 4: Put the electrified bottom soil into a plate and frame filter press for processing. The bottom soil has small particle size, contains a small amount of heavy metals and is rich in organic matter. The input organic materials are dehydrated through a plate and frame filter press to reduce the moisture content rate to 65%;

Step 5. Mix the sludge dehydrated in step 4 with the biomass powder, then add the alkaline additive mixture of CaO, Ca(OH) ₂ , NaOH and Na ₅ P ₃ O ₁₀ and an appropriate amount of distilled water, and stir evenly. A precursor mixture is obtained. Among them, the mass ratio of soft mud, biomass powder, alkaline additive mixture and distilled water is 15:2::2:1; among them, the mass ratio of CaO, Ca(OH) ₂ , NaOH and Na ₅ P ₃ O ₁₀ is 1:1.5.:1.5:1; Preparation method of biomass powder: First process the biomass raw materials to remove impurities and moisture, dry them, use a pulverizer to grind the biomass raw materials into powder, and sieve the powder. Remove particles that do not meet the requirements, and then dry the powder to remove moisture. The particle size of the biomass powder is 100 mesh;

Step 6: Place the precursor mixture in a high-pressure reactor, and add enough water to the reaction volume to ensure that the hydrothermal reaction proceeds adequately. Then raise the pressure of the high-pressure reaction kettle to 5MPa, heat the high-pressure reaction kettle to 200°C, and after 28 hours of reaction, cool the high-pressure reaction kettle, reduce the pressure and open the high-pressure reaction kettle;

Step 7: Set the centrifugal speed to 4000r/min. After the reaction product is centrifuged for 15 minutes, liquid product I and solid product I are obtained. Among them, liquid product I can be used as a liquid compound fertilizer;

Step 8. After the solid product I is digested with a mixed acid of 30% mass fraction of concentrated nitric acid, 65% mass fraction of nitric acid, 25% mass fraction of sulfuric acid and 10% mass fraction of hydrochloric acid, the solid product I is centrifuged to obtain the solid product II and liquid product II. The solid product II is washed with deionized water until neutral and vacuum dried to obtain hydrothermal biochar and soil that can be used for planting;

Step 9: Add the reducing agent sodium sulfite to the liquid product II and react for 16 hours. The volume ratio of the mass of the reducing agent to the liquid product II is 20g:100mL. Then perform centrifugal separation to obtain heavy metal precipitation.

Comparative example 1:

Step 1: Dehydrate the collected seabed mining soil through a dewatering vibrating screen to achieve a moisture content of 35%;

Step 2: Sieve the bottom soil obtained by dehydration treatment through a three-stage vibrating sieve, and collect the final undersize - bottom soil rich in organic matter and a small amount of heavy metals;

Step 3: Put the sieved objects into a container filled with water. At the same time, set a 20kHz electrode in the container. Both the positive and negative electrodes are carbon rods. Concentrate heavy metal cations onto the positive carbon rod through 20kHz direct current. This process lasts for three minutes, and finally the heavy metals on the carbon rod are collected;

Step 4: Put the electrified bottom soil into a plate and frame filter press for processing. The bottom soil has small particle size, contains a small amount of heavy metals and is rich in organic matter. Through the plate and frame filter press, the input organic materials are dehydrated and the moisture content rate is reduced to 60%;

Step 5. Mix the sludge dehydrated in step 4 with the biomass powder, then add the alkaline additive mixture of CaO, Ca(OH) ₂ , NaOH and Na ₅ P ₃ O ₁₀ and an appropriate amount of distilled water, and stir evenly. A precursor mixture is obtained. Among them, the mass ratio of soft mud, biomass powder, alkaline additive mixture and distilled water is 1.5:1.5::2:1; among them, the mass ratio of CaO, Ca(OH) ₂ , NaOH and Na ₅ P ₃ O ₁₀ is 1:1.5.:1.5:1; Preparation method of biomass powder: First process the biomass raw materials to remove impurities and moisture, dry them, use a pulverizer to grind the biomass raw materials into powder, and sieve the powder. Remove particles that do not meet the requirements, and then dry the powder to remove moisture. The particle size of the biomass powder is 100 mesh;

Step 6: Place the precursor mixture in a high-pressure reactor, and add enough water to the reaction volume to ensure that the hydrothermal reaction proceeds adequately. Then the pressure of the high-pressure reaction kettle was increased to 1.5MPa, and the high-pressure reaction kettle was heated to 190°C. After 28 hours of reaction, the high-pressure reaction kettle was cooled, and the pressure was reduced and the high-pressure reaction kettle was opened;

Step 7: Set the centrifugal speed to 4000r/min. After the reaction product is centrifuged for 15 minutes, liquid product I and solid product I are obtained. Among them, liquid product I can be used as a liquid compound fertilizer;

Step 8. After the solid product I is digested with a mixed acid of 30% mass fraction of concentrated nitric acid, 65% mass fraction of nitric acid, 25% mass fraction of sulfuric acid and 10% mass fraction of hydrochloric acid, the solid product I is centrifuged to obtain the solid product II and liquid product II. The solid product II is washed with deionized water until neutral and vacuum dried to obtain hydrothermal biochar and soil that can be used for planting;

Step 9: Add the reducing agent sodium sulfite to the liquid product II and react for 16 hours. The volume ratio of the mass of the reducing agent to the liquid product II is 10g:100mL. Then perform centrifugal separation to obtain heavy metal precipitation.

Comparative example 2:

Step 1: Add an alkaline additive mixture of CaO, Ca(OH) ₂ , NaOH and Na ₅ P ₃ O ₁₀ and an appropriate amount of distilled water to the seabed mining soil dehydrated by the vibrating screen, and stir evenly to obtain a precursor mixture. Among them, the mass ratio of seabed mining soil, alkaline additive mixture and distilled water is 15:2:1; among them, the mass ratio of CaO, Ca(OH) ₂ , NaOH and Na ₅ P ₃ O ₁₀ is 1:1.5.:1.5 :1;

Step 2: Place the precursor mixture in a high-pressure reactor, and add enough water to the reaction volume to ensure that the hydrothermal reaction proceeds adequately. Then the pressure of the high-pressure reaction kettle was raised to 1.5MPa, and the high-pressure reaction kettle was heated to 180°C. After 20 hours, cool the high-pressure reaction kettle and reduce the pressure before opening the high-pressure reaction kettle;

Step 3: Set the centrifugal speed to 4000 r/min. After the reaction product is centrifuged for 15 minutes, liquid product I and solid product I are obtained. Among them, liquid product I can be used as liquid compound fertilizer;

Step 4: The solid product I is digested with 30% concentrated nitric acid mixed acid, 65% nitric acid, 25% sulfuric acid and 10% hydrochloric acid, and then centrifuged to obtain the solid product. II and liquid product II. The solid product II is washed with deionized water until neutral and vacuum dried to obtain hydrothermal biochar and soil that can be used for planting;

Step 5: Add sodium sulfite to the liquid product II and react for 16 hours, then perform centrifugal separation to obtain heavy metals. The volume ratio of the mass of the reducing agent to the liquid product II is 0.55:25;

The mass proportions of various resource outputs of seabed mining soil under the processing conditions of the above-mentioned Example 1, Example 2, Comparative Example 1, and Comparative Example 2 are shown in Table 1;

Table 1

The comparison of the heavy metal element content in the soil produced in Example 1 and the seabed mining soil is shown in Table 2.

Table 2

It can be seen from Table 2 that the average contents of Co, Cr, Cu, Pb, Zn, Cd, and Hg in seabed mining soil are 11.45 mg/kg, 61.79 mg/kg, 15.24 mg/kg, 23.16 mg/kg, and 52.23 mg/kg, respectively. kg, 0.079mg/kg, 0.044mg/kg. In the soil produced in Example 1 that can be used for planting, the Co ion concentration dropped from 11.95mg/kg to 34.2μg/kg, and the Cr ion concentration dropped from 60.79mg/kg. 94.1μg/l, Cu ion concentration dropped from 17.24mg/kg to 14.2μg/kg, Pb ion concentration dropped from 26.18mg/kg to 23.4μg/kg, Zn ion concentration dropped from 51.22mg/kg to 84.2μg/kg, The Cd ion concentration dropped from 0.081mg/kg to 3.8μg/kg, and the Hg ion concentration dropped from 0.043mg/kg to 27.6μg/kg.

Those of ordinary skill in the art should realize that the above embodiments are only used to illustrate the present application and are not used to limit the present application. As long as the above embodiments are appropriately modified within the scope of the essential spirit of the present application, Changes and variations are within the scope of protection claimed by this application.

Claims (10)

1. A method for utilizing seabed mining soil resources, which is characterized in that it includes the following steps in sequence: a. Dehydration: dehydrate the slurry collected from seabed mining so that its moisture content reaches 30 to 40%; b. Screening, the bottom soil obtained by the dehydration treatment in step a is graded and screened to obtain the undersize, which is bottom soil rich in organic matter and a certain amount of heavy metals; c. Electrify the under-sieve objects, put the under-sieve objects into a container filled with water, set high-frequency and low-frequency electrodes in the container, and destroy the under-sieve objects by passing high-frequency alternating current into the container. The chemical bond is used to enrich the heavy metal cations contained in the undersize onto the positive carbon rod by passing low-frequency direct current into the container, and collect the heavy metals on the positive carbon rod; d. Plate and frame filter press processing: put the bottom soil after electrification in step c into the plate and frame filter press for processing, and dehydrate the input organic materials to reduce their moisture content to 55 to 65 %; e. Prepare a precursor mixture, mix the sludge obtained after step d with biomass powder, add alkaline additives and distilled water to it, and stir evenly to obtain a precursor mixture; f. Reaction, placing the precursor mixture described in step e in a high-pressure reactor for reaction, centrifuging the resulting reaction product to obtain liquid product I and solid product I, wherein liquid product I is used as a liquid compound fertilizer; g. After solid product I is digested with strong acid, centrifugal separation is performed to obtain liquid product II and solid product II. Solid product II is washed with deionized water to neutrality and vacuum dried to obtain hydrothermal biochar and can be used for planting. Soil; h. Add a reducing agent to the liquid product II for reaction, and then undergo centrifugal separation to obtain the solid material which is the heavy metal. 2. A method for utilizing soil resources in seabed mining according to claim 1, characterized in that: in step a, the slurry collected in seabed mining is lifted to the mother ship through a riser and dehydrated through a dewatering vibrating screen. 3. A method for utilizing seabed mining soil resources according to claim 1, characterized in that: in step b, the bottom soil obtained after dehydration treatment is subjected to a three-stage screening process, wherein, in the first-level screening process, The first-level vibrating screen selected is a 10-mesh screen, the second-level vibrating screen selected in the second-level screening process is a 100-mesh screen, and the third-level vibrating screen selected in the third-level screening process is a 200-mesh screen. 4. A method for utilizing seabed mining soil resources according to claim 1, characterized in that: in step b, the heavy metals contained in the undersize are Cr, Cd, Ga, Cu, Ni, Co, Pb, Zn , Mn and Fe metal ions. 5. A method for utilizing seabed mining soil resources according to claim 1, characterized in that: in step e, the preparation method of the biomass powder is: cleaning the biomass raw materials and removing impurities, and then Dry and grind it into powder; sieve the powdered biomass raw materials to retain the biomass powder that meets the requirements. After drying and removing moisture in sequence, biomass with a particle size of 100 to 200 mesh is obtained. Powder; the biomass raw material is selected from seaweed and/or marine animal and plant corpses. 6. A method for utilizing seabed mining soil resources according to claim 5, characterized in that: the alkaline auxiliary agent is NaOH, KOH, CaO and Ca(OH) ₂ , Na ₂ CO ₃ and Na ₅ One or more mixtures of P ₃ O ₁₀ , in which the mass ratio of CaO and Ca(OH) ₂ to Na ₂ CO ₃ and Na ₅ P ₃ O ₁₀ is 1:1; ooze, biomass powder, The mass ratio of alkaline additives and distilled water is 1~50:0.3~5:0.25~2:0.1~30. 7. A method for utilizing seabed mining soil resources according to claim 1, characterized in that: in step f, sufficient water is added to the high-pressure reaction kettle to ensure the progress of the hydrothermal reaction, and the temperature of the hydrothermal reaction is 180~200℃, the pressure of hydrothermal reaction is 1.5~5MPa, and the time of hydrothermal reaction is 20~28h. 8. A method for utilizing seabed mining soil resources according to claim 1, characterized in that: in step g, the strong acid is aqua regia and perchloric acid with a mass fraction of 70% and a mass fraction of 30%. A mixed acid obtained by mixing concentrated nitric acid; or a mixed acid obtained by mixing aqua regia with nitric acid with a mass fraction of 65%, sulfuric acid with a mass fraction of 25%, and hydrochloric acid with a mass fraction of 10%; or aqua regia with a mass fraction of 95 % sulfuric acid and 5% hydrofluoric acid; or a mixed acid obtained by mixing aqua regia with 70% concentrated nitric acid and 30% concentrated hydrochloric acid; the speed of centrifugal separation is 4000 ~12000r/min, centrifugation time is 15~30min; vacuum drying temperature is 70~80℃, vacuum drying time is 20~24h; after vacuum drying, use 10 mesh screen for screening, and the top of the screen after screening It is hydrothermal biochar, and underneath the screen is soil that can be used for planting. 9. A method for utilizing seabed mining soil resources according to claim 1, characterized in that: in step h, the reducing agent is sodium sulfite, sodium bisulfite, sodium nitrite, ferrous sulfate, potassium borohydride, cyanide One or more of sodium borohydride or sodium borohydride; the mass ratio of the reducing agent to the volume of the liquid product II is 0.5~20g:20~100mL, and the reaction time of adding the reducing agent is 3~24h. 10. A method for utilizing seabed mining soil resources according to any one of claims 1 to 9, characterized in that all steps are completed on the mother ship; the liquid compound fertilizer is rich in phosphorus and humus, and is soluble The proportion of phosphorus is 45% to 65%, and the content of humus is 0.01% to 0.03%.