Method for harmless and resourceful utilization of water pipe dirt

Abstract

The present application preliminarily separates heavy metals from part of iron oxides and other substances through acidolysis, and further realizes the precipitation and separation of heavy metal ions and conventional metal ions through pH control and adjustment of precipitation rate by means of step-by-step precipitation of alkali solution. In addition, the reduction of carbonized iron oxides of organic matter is realized through the carbon thermal reduction method, and silico-aluminate can be used as a structure aid for preparing iron-carbon material ceramsite products. For trace heavy metal waste liquid, the prepared iron-carbon material ceramsite product can be used for adsorption separation and enrichment, and further carbon removal through calcination, so as to realize the enrichment recovery or mineralization of heavy metal elements.

Description

Technical Field

[0001] The present invention belongs to the technical field of wastewater treatment, and in particular relates to a harmless process for pipe scale and a method for preparing iron-carbon material ceramsite based on pipe scale. Background Art

[0002] Over the past few decades, with the advancement of water quality regulations and water purification technologies, many water utilities have improved water quality by selecting better water sources and upgrading water treatment processes. Although the quality parameters of treated water meet national drinking water standards, when treated water is delivered to consumers through pipes, pollutants accumulated in pipe fouling can be released back into the treated water, reducing water quality at the consumer end and jeopardizing the water quality safety of the water supply system. Many water discoloration issues have been attributed to the release of particulate matter from pipes, even in plastic pipes that are not subject to corrosion. In addition to discoloration issues, there have been reports that the release of sediment containing harmful bacteria such as E. coli is associated with an increased risk of acute gastrointestinal illness and decreased liver cell viability in humans.

[0003] Pipe scale is typically composed of corrosion flakes, sediments, heavy metals, microorganisms, and organic matter. Corrosion flakes originate from the pipe wall and grow radially toward the center of the pipe. Typical iron-based pipe corrosion scale is usually composed of four layers: a corroded metal base plate, an internal porous core layer, a compact shell layer, and a loose sediment layer on the surface of the corrosion flakes. When sediments adhere to the pipe wall or corrosion flakes, free heavy metal ions, microorganisms, and organic pollutants in the water will accumulate in the sediment layer. Under normal circumstances, pollutants will accumulate in the pipe scale, but once the pipe is disturbed, especially under changing hydrodynamic conditions, the pollutants accumulated in the sediment will be resuspended, causing water quality deterioration. In addition, water pipe scale can also restrict water flow, increase water pipe pressure, and may even cause water pipe bursts, causing many inconveniences to industrial production.

[0004] The commonly used pipeline cleaning technologies at home and abroad include one-way flushing technology, PIG cleaning technology, air-water pulse technology, ice cleaning technology and high-pressure water jet, etc. In addition to these mainstream cleaning methods, there are also many patents for new devices and methods for removing water pipe dirt in China, such as CN108246739A, CN106269731A, CN113245319A, CN111043776A and CN106269731A, etc. These patents are committed to providing new ideas and methods for removing water pipe dirt. However, there is currently no corresponding treatment technology for the cleaned water pipe dirt. Water pipe dirt contains heavy metals and organic pollutants, which need to be harmlessly treated, and a large amount of iron oxide contained in the pipe dirt is a useful resource and is widely used in environmental governance. For example, ferric oxide can remove heavy metal ions and organic matter in water due to its good adsorption performance and catalytic activity; ferric oxide can be used for pollutant adsorption and catalytic decomposition.

[0005] Iron-carbon material composite treatment technology refers to a method of using activated carbon and zero-valent iron in combination to treat heavy metal wastewater. The mechanism of action of iron-carbon material composite treatment technology is to form a primary cell by utilizing the potential difference between zero-valent iron and carbon material, so as to occur electrode reaction process to treat wastewater. The oxidation-reduction reaction on the surface of iron-carbon material is beneficial to the removal of heavy metal complex wastewater, and the coagulation effect of ferrous iron and the precipitation of iron ions generated in the electric reaction are beneficial to the removal of pollutants. The advantages of iron-carbon composite treatment technology are low energy consumption, no secondary pollution, and simple operation, which is often used in industrial wastewater decolorization and adsorption treatment. The iron oxide and organic matter in the water pipe dirt can be used as the iron source and carbon source of the iron-carbon material respectively, and the iron-carbon material ceramic product can be prepared by appropriately supplementing the carbon material. Moreover, considering the environmental health hazards of water pipe dirt and the increasingly strict restrictions on solid waste and hazardous waste emissions by the state, it is necessary to harmlessly and resourcefully dispose of the solid waste and hazardous waste generated by pipeline cleaning. SUMMARY

[0006] In view of the technical problems existing in the prior art, the purpose of the present application is to provide a harmless treatment method for heavy metal and other pollutants in water pipe dirt, and to resourcefully utilize the iron oxide and organic matter contained in the water pipe dirt.

[0007] In order to achieve the above purposes, the present application adopts the following technical scheme: a harmless and resourceful utilization method of water pipe dirt, the method comprising the following steps:

[0008] (1) adding a certain concentration of acid to a reactor containing crushed water pipe dirt, and after a period of time, filtering the mixture in the reactor to obtain a metal salt mother liquor and an insoluble mud;

[0009] (2) Metal salt mother liquor adopts alkali solution step-by-step precipitation mode to realize heavy metal ion and conventional metal ion precipitation and separation, and obtain trace heavy metal waste liquid and iron-rich mud material;

[0010] (3) The insoluble mud material and the iron-rich mud material obtained in steps (1) and (2) are mixed uniformly, and are placed in an oven for drying, and then are placed in a pulverizer for pulverization; in addition, the carbon material is placed in the pulverizer for pulverization, and the pulverized mud material and the carbon material are sieved;

[0011] (4) The carbon powder and the mud material of a certain mesh are mixed according to a certain proportion, and a kaolin clay binder and a glass fiber reinforcing agent are added, and the mixture is stirred and mixed uniformly in a stirrer, and then an appropriate amount of water is added to adjust the mixture into a uniform plastic mud material, and the mud material is extruded into a shape to obtain particles of the same size;

[0012] (5) The particles obtained in step (4) are placed in a carbonization furnace for carbon thermal reduction treatment in a nitrogen atmosphere to obtain an iron-carbon material ceramsite product;

[0013] (6) A certain amount of the iron-carbon material ceramsite product obtained in step (5) is added to the trace heavy metal waste liquid to realize adsorption, enrichment recovery or mineralization of heavy metals.

[0014] The present application preliminarily separates heavy metals from part of iron oxides and the like through acidolysis, and further realizes the precipitation and separation of heavy metal ions and conventional metal ions through step-by-step precipitation of an alkali solution, pH control and adjustment of deposition rate; the carbonization of organic matter and the reduction of iron oxides are realized through a carbon thermal reduction method, and silicate can be used as a structure aid to prepare an iron-carbon material ceramsite product; for trace heavy metal waste liquid, the prepared iron-carbon material ceramsite product is used for adsorption separation and enrichment, and further carbon removal through calcination realizes the enrichment recovery or mineralization of heavy metal elements.

[0015] Preferably, the acid in step (1) is nitric acid, sulfuric acid, hydrochloric acid or phosphoric acid;

[0016] Preferably, the mass concentration of the sulfuric acid in step (1) is not less than 20%.

[0017] Preferably, the mass ratio of the acid to the water pipe dirt in step (1) is 1-5, for example, 1, 2, 3, 4 or 5; but is not limited to the listed values, and other values not listed in the above value range are also applicable.

[0018] Preferably, the acidolysis time in step (1) is 6-24h, for example, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h or 24h; but is not limited to the listed values, and other values not listed in the above value range are also applicable.

[0019] Characterized in that the alkaline solution in step (2) is a mixture of one or more of NaOH, KOH, NH4OH, Na2CO3, and K2CO3;

[0020] It is characterized in that the concentration of the alkaline solution in step (2) is an alkaline solution molar concentration of 1-40%, for example, it can be 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, etc.; but it is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable;

[0021] It is characterized in that the reaction temperature of the alkaline solution stepwise precipitation in step (2) is 20-80°C, for example, it can be 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, etc.; but it is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable;

[0022] It is characterized in that the mass ratio of the metal salt mother liquor to the alkaline solution in step (2) is 1-10, for example, it can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc.; but it is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable;

[0023] It is characterized in that the mass ratio of the insoluble mud and the iron-rich mud in step (3) is 1:1-1:10, for example, it can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, etc.; but it is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable;

[0024] It is characterized in that the oven temperature in step (3) is 60-150°C, for example, it can be 60°C, 70°C, 80°C, 90°C, 110°C, 120°C, 130°C, 140°C, 150°C, etc.; but it is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable;

[0025] Characterized in that the crushed and sieved particle sizes of the mud and carbon material in step (3) are 1-8 mesh, 10-30 mesh, 40-60 mesh, 100-200 mesh, and 300-400 mesh;

[0026] It is characterized in that the mass ratio of the carbon powder and the mud material in step (4) is 1:1-1:10, for example, it can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, etc.; but it is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable;

[0027] In the step (4), the particle size of the extrusion molding is 2-20 mm, for example, 2 mm, 4 mm, 6 mm, 8 mm, 10 mm, 12 mm, 14 mm, 16 mm, 18 mm, 18 mm, etc., but not limited to the listed values, and other values not listed in the above value range are also applicable.

[0028] In the step (5), the carbon thermal reduction temperature is 700-1000℃, for example, 700℃, 750℃, 800℃, 850℃, 900℃, 950℃, 1000℃, etc., but not limited to the listed values, and other values not listed in the above value range are also applicable.

[0029] In the step (5), the carbon thermal reduction time is 1-6 h, for example, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h, 6 h, etc., but not limited to the listed values, and other values not listed in the above value range are also applicable.

[0030] In the step (5), the dosage of the iron-carbon material ceramsite product is 10-100 g / L, for example, 10 g / L, 20 g / L, 30 g / L, 40 g / L, 50 g / L, 60 g / L, 70 g / L, 80 g / L, 90 g / L, 100 g / L, etc., but not limited to the listed values, and other values not listed in the above value range are also applicable.

[0031] In the step (6), the heavy metals include Mn, Pb, Ba, As, Cr, Ni and V.

[0032] As a preferred technical solution of the present application, the preparation method comprises the following steps:

[0033] (1) adding sulfuric acid with a mass concentration of not less than 20% to a reactor containing crushed water pipe fouling, wherein the mass ratio of sulfuric acid to water pipe fouling is 1-5, and after 6-24 h, the mixture in the reactor is filtered to obtain a metal salt mother liquor and an insoluble mud;

[0034] (2) using a mixed alkali solution containing one or more of NaOH, KOH, NH4OH, Na2CO3 and K2CO3 with a molar concentration of 1-40% to realize the precipitation and separation of heavy metal ions and conventional metal ions at 20-80℃, to obtain a trace heavy metal waste liquid and an iron-rich mud;

[0035] (3) mix the insoluble sludge and the iron-rich sludge obtained in steps (1) and (2) uniformly, the mass ratio of the insoluble sludge and the iron-rich sludge is 1:1-1:10, and then put them into an oven at 60-150℃ for drying, and then put them into a pulverizer for pulverization; additionally, put the carbon material into the pulverizer for pulverization, and sieve the pulverized sludge and carbon material;

[0036] (4) mix the carbon powder and the sludge of a certain mesh size according to a mass ratio of 1:1-1:10, add a binder such as kaolin and a reinforcing agent such as glass fiber, mix them uniformly in a stirring machine, add an appropriate amount of water to adjust them into uniform plastic sludge, and extrude them to form particles of the same particle size, the particle size of the extruded particles is 2-20 mm;

[0037] (5) put the particles obtained in step (4) into a carbonization furnace, and perform carbon thermal reduction treatment under a nitrogen atmosphere, the carbon thermal reduction temperature ranges from 700 to 1000℃, and an iron-carbon material ceramsite product is obtained;

[0038] (6) add a certain amount of the iron-carbon material ceramsite product obtained in step (5) to a trace heavy metal waste liquid, the addition amount of the iron-carbon material ceramsite product is 10-100 g / L, and adsorption, enrichment recovery or mineralization of heavy metals are realized.

[0039] Compared with the prior art, the present application has the following advantages: the present application uses water pipe dirt as raw material, realizes carbonization of organic matter and reduction of iron oxide through carbon thermal reduction method, and at the same time, silicate and aluminate can be used as a structure aid to prepare an iron-carbon material ceramsite product; the prepared iron-carbon material ceramsite product is used for adsorption separation and enrichment of trace heavy metal waste liquid, and further carbon removal through calcination is performed, so that enrichment recovery or mineralization of heavy metal elements is realized, and self-recovery and utilization of water pipe dirt are completed. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 The technical roadmap of the harmless process of the pipe dirt and the preparation method of the iron-carbon material ceramsite based on the pipe dirt is shown in the figure. DETAILED DESCRIPTION

[0041] The technical solutions of the present application will be further described through specific embodiments. Those skilled in the art should understand that the embodiments are only used to help understand the present application, and should not be regarded as specific limitations on the present application.

[0042] The harmless and resource utilization method of the water pipe dirt of the present application comprises the following steps:

[0043] (1) add an acid of a certain concentration to a reactor containing pulverized water pipe dirt, filter the mixture in the reactor after a period of time, and obtain a metal salt mother liquor and insoluble sludge;

[0044] (2) The metal salt mother liquor is precipitated by alkali solution step by step to realize the precipitation and separation of heavy metal ions and conventional metal ions, and obtain trace heavy metal waste liquid and iron-rich mud;

[0045] (3) The insoluble mud and iron-rich mud obtained in steps (1) and (2) are mixed uniformly, and then dried in an oven and crushed in a crusher; additionally, carbon materials are crushed in a crusher, and the crushed mud and carbon materials are sieved;

[0046] (4) Carbon powder and mud of a certain mesh are mixed according to a certain proportion, and kaolin adhesive and glass fiber reinforcing agent are added, and then stirred and mixed uniformly in a stirrer, and then a proper amount of water is added to adjust the mixture into uniform plastic mud, and then extruded into particles of the same size;

[0047] (5) The particles obtained in step (4) are placed in a carbonization furnace for carbon thermal reduction treatment under a nitrogen atmosphere to obtain iron-carbon material ceramsite products;

[0048] (6) A certain amount of iron-carbon material ceramsite products obtained in step (5) is added to the trace heavy metal waste liquid to realize the adsorption, enrichment and recovery or mineralization of heavy metals.

[0049] The following examples all use the above method.

[0050] Example 1

[0051] The present embodiment provides a harmless and resource utilization method of water pipe dirt, which comprises the following steps:

[0052] (1) 30% sulfuric acid is added to a reactor containing crushed water pipe dirt, wherein the mass ratio of sulfuric acid to water pipe dirt is 2:12, and after 12 hours, the mixture in the reactor is filtered to obtain metal salt mother liquor and insoluble mud;

[0053] (2) The metal salt mother liquor is precipitated by 20% alkali solution containing NaOH at 60°C to realize the precipitation and separation of heavy metal ions and conventional metal ions, and obtain trace heavy metal waste liquid and iron-rich mud;

[0054] (3) The insoluble mud and iron-rich mud obtained in steps (1) and (2) are mixed uniformly, and the mass ratio of insoluble mud to iron-rich mud is 1:2, and then dried in a 105°C oven and crushed in a crusher; additionally, carbon materials are crushed in a crusher, and the crushed mud and carbon materials are sieved through a 50 mesh sieve;

[0055] (4) 200 mesh carbon powder and mud are mixed according to a mass ratio of 1:5, while adding a binder such as kaolin, a reinforcing agent such as glass fiber, and the like, and after being stirred and mixed uniformly in a stirrer, a proper amount of water is added to adjust into a uniform plastic mud, and extrusion molding is performed to obtain particles of the same size, and the particle size of the extrusion molding is 5 mm;

[0056] (5) The particles obtained in step (4) are placed in a carbonization furnace, and carbon thermal reduction treatment is performed under a nitrogen atmosphere, and the carbon thermal reduction temperature range is 800°C, and an iron-carbon material ceramsite product is obtained;

[0057] (6) A certain amount of the iron-carbon material ceramsite product obtained in step (5) is added to a trace heavy metal waste liquid, and the iron-carbon material ceramsite product is added in an amount of 20 g / L, and adsorption, enrichment recovery or mineralization of heavy metals is achieved, and the adsorption efficiency of Mn and Pb reaches 99%, and the adsorption efficiency of Ba, As and Cr is 93%, 96% and 97%, respectively.

[0058] Example 2

[0059] The present embodiment provides a harmless and resource utilization method for water pipe dirt, and the preparation method comprises the following steps:

[0060] (1) Sulfuric acid with a mass concentration of 40% is added to a reactor containing crushed water pipe dirt, and the mass ratio of sulfuric acid to water pipe dirt is 2:12, and after 12 hours, the mixture in the reactor is filtered to obtain a metal salt mother liquor and insoluble mud;

[0061] (2) The metal salt mother liquor is subjected to precipitation and separation of heavy metal ions and conventional metal ions using an alkali solution containing NaOH with a molar concentration of 20% at 60°C to obtain a trace heavy metal waste liquid and an iron-rich mud;

[0062] (3) The insoluble mud and the iron-rich mud obtained in steps (1) and (2) are mixed uniformly, and the mass ratio of the insoluble mud to the iron-rich mud is 1:2, and then they are placed in an oven at 105°C for drying, and then they are crushed in a crusher; in addition, carbon material is crushed in a crusher, and the crushed mud and carbon material are passed through a 50-mesh sieve;

[0063] (4) 200 mesh carbon powder and mud are mixed according to a mass ratio of 1:5, while adding a binder such as kaolin, a reinforcing agent such as glass fiber, and the like, and after being stirred and mixed uniformly in a stirrer, a proper amount of water is added to adjust into a uniform plastic mud, and extrusion molding is performed to obtain particles of the same size, and the particle size of the extrusion molding is 4 mm;

[0064] (5) The particles obtained in step (4) are placed in a carbonization furnace, and carbon thermal reduction treatment is performed under a nitrogen atmosphere, and the carbon thermal reduction temperature range is 850°C, and an iron-carbon material ceramsite product is obtained;

[0065] (6) adding a certain amount of the iron-carbon material ceramsite product obtained in step (5) into the trace heavy metal waste liquid, the iron-carbon material ceramsite product dosage being 20 g / L, to realize adsorption, enrichment recovery or mineralization of the heavy metals, wherein the adsorption efficiency of Mn and Pb is 97% and 98% respectively, and the adsorption efficiency of Ba, As and Cr is 91%, 92% and 95% respectively.

[0066] Example 3

[0067] The present embodiment provides a harmless and resource utilization method of water pipe dirt, and the preparation method comprises the following steps:

[0068] (1) adding sulfuric acid with a mass concentration of 40% into a reactor containing the water pipe dirt after being crushed, wherein the mass ratio of sulfuric acid to water pipe dirt is 3, and after 12 h, the mixture in the reactor is filtered to obtain a metal salt mother liquor and insoluble mud;

[0069] (2) using an alkali solution containing KOH with a molar concentration of 30% to realize the precipitation and separation of heavy metal ions and conventional metal ions at 60°C, to obtain a trace heavy metal waste liquid and an iron-rich mud;

[0070] (3) mixing the insoluble mud and the iron-rich mud obtained in steps (1) and (2) uniformly, the mass ratio of the insoluble mud to the iron-rich mud being 1:2, and placing them into an oven at 105°C for drying, and then placing them into a crusher for crushing; additionally, crushing the carbon material in the crusher, and passing the crushed mud and carbon material through a 50-mesh sieve;

[0071] (4) mixing the carbon powder with a mesh number of 200 and the mud according to a mass ratio of 1:3, simultaneously adding a binder such as kaolin and a reinforcing agent such as glass fiber, stirring and mixing them uniformly in a stirrer, adding an appropriate amount of water to adjust them into uniform plastic mud, and extruding them into a shape to obtain particles with the same particle size, the particle size of the extruded particles being 6 mm;

[0072] (5) placing the particles obtained in step (4) into a carbonization furnace to perform carbon thermal reduction treatment under a nitrogen atmosphere, the carbon thermal reduction temperature range being 800°C, to obtain an iron-carbon material ceramsite product;

[0073] (6) adding a certain amount of the iron-carbon material ceramsite product obtained in step (5) into the trace heavy metal waste liquid, the iron-carbon material ceramsite product dosage being 30 g / L, to realize adsorption, enrichment recovery or mineralization of the heavy metals, wherein the adsorption efficiency of Mn and Pb is 98% and 99% respectively, and the adsorption efficiency of Ba, As and Cr is 95%, 95% and 97% respectively.

[0074] Comparative Example 1

[0075] The embodiment provides a harmless and resource utilization method of water pipe dirt, and the preparation method comprises the following steps:

[0076] (1) adding 5% sulfuric acid in mass concentration into a reactor containing the water pipe dirt after crushing, wherein the mass ratio of sulfuric acid to the water pipe dirt is 10, and after 12 hours, the mixture in the reactor is filtered to obtain a metal salt mother liquor and insoluble mud;

[0077] (2) the metal salt mother liquor is subjected to precipitation and separation of heavy metal ions and conventional metal ions by using 10% alkali solution containing NaCO3 in molar concentration at 60 DEG C to obtain trace heavy metal waste liquid and iron-rich mud;

[0078] (3) mixing the insoluble mud and the iron-rich mud obtained in steps (1) and (2) uniformly, the mass ratio of the insoluble mud to the iron-rich mud is 1:2, and the mixture is placed into an oven at 105 DEG C for drying, and then is placed into a crusher for crushing; additionally, carbon material is placed into the crusher for crushing, and the crushed mud and the carbon material are passed through a 50-mesh screen;

[0079] (4) mixing 100-mesh carbon powder and mud according to a mass ratio of 1:5, simultaneously adding a binder such as kaolin and a reinforcing agent such as glass fiber, stirring and mixing the mixture uniformly in a stirrer, adding an appropriate amount of water to adjust the mixture into uniform plastic mud, and extruding the mixture to form particles of the same size, wherein the particle size of the extruded particles is 5 mm;

[0080] (5) placing the particles obtained in step (4) into a carbonization furnace, and performing carbon thermal reduction treatment under a nitrogen atmosphere, wherein the carbon thermal reduction temperature ranges from 650 DEG C, and iron-carbon material ceramsite products are obtained;

[0081] (6) adding a certain amount of the iron-carbon material ceramsite products obtained in step (5) into the trace heavy metal waste liquid, wherein the addition amount of the iron-carbon material ceramsite products is 20 g / L, adsorption, enrichment recovery or mineralization of heavy metals are realized, wherein the adsorption efficiency of Mn and Pb is 56% and 63% respectively, and the adsorption efficiency of Ba, As and Cr is 43%, 34% and 42% respectively.

Claims

1. A method for harmless and resourceful utilization of water pipe dirt, characterized in that: The method comprises the following steps: (1) Acid with a mass concentration of 30% or 40% is added to a reactor containing crushed water pipe dirt for acid hydrolysis. After a period of time, the mixture in the reactor is filtered to obtain a metal salt mother liquor and an insoluble mud material; The acid in step (1) is nitric acid, sulfuric acid, hydrochloric acid or phosphoric acid; The mass ratio of the acid to the water pipe dirt in step (1) is 1 to 5; The acid hydrolysis time in step (1) is 6 to 24 hours; (2) The metal salt mother liquor is precipitated and separated from heavy metal ions and conventional metal ions by a step-by-step precipitation method using an alkaline solution, thereby obtaining a trace amount of heavy metal waste liquid and iron-rich mud; The alkaline solution in step (2) contains one or both of NaOH and KOH; The concentration of the alkaline solution in step (2) is 1% to 40%; The reaction temperature of the alkaline solution stepwise precipitation in step (2) is 20-80°C; The mass ratio of the metal salt mother liquor to the alkaline solution in step (2) is 1 to 10; (3) The insoluble mud and the iron-rich mud obtained in step (1) and step (2) are mixed evenly, placed in an oven for drying, and then placed in a grinder for crushing; the charcoal is placed in a grinder for crushing, and the crushed mud and charcoal powder are sieved; The mass ratio of the insoluble mud and the iron-rich mud in step (3) is 1:1 to 1:10; The oven temperature in step (3) is 60-150° C. The crushed mud and carbon powder in step (3) are sieved to a particle size of any one of 1-8 mesh, 10-30 mesh, 40-60 mesh, 100-200 mesh or 300-400 mesh; (4) Mixing carbon powder of a certain mesh size and clay in a certain proportion, adding kaolin binder and glass fiber reinforcement, stirring and mixing in a blender until uniform, adding appropriate amount of water to form a uniform plastic clay, and extruding to obtain particles of the same particle size; The mass ratio of the carbon powder and the clay mixed in step (4) is 1:1 to 1:10; The particle size of the extrusion molding in step (4) is 2 to 20 mm; (5) placing the particles obtained in step (4) in a carbonization furnace and performing carbon thermal reduction treatment under a nitrogen atmosphere, Obtain iron-carbon material ceramsite products; The carbon thermal reduction temperature in step (5) is 700-1000° C. The carbon thermal reduction time in step (5) is 1 to 6 hours; (6) adding a certain amount of the iron-carbon material ceramsite product obtained in step (5) to the trace heavy metal waste liquid to achieve adsorption, enrichment, recovery or mineralization of heavy metals; The dosage of the iron-carbon material ceramsite product in step (6) is 10-100 g / L; The heavy metals in step (6) include Mn, Pb, Ba, Cr, Ni and V.

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