A method for producing sulfuric acid and co-producing mine filling cementitious filling by using phosphogypsum

Abstract

The application discloses a kind of phosphogypsum preparation sulfuric acid coproduction mine filling cementitious filling methods, raw materials include phosphogypsum clinker and other materials, the weight ratio of phosphogypsum clinker and other materials is 1:4 to 10, the other material refers to tailings and waste rock;The sulfur dioxide produced after heating and high-temperature decomposition of phosphogypsum is used to prepare sulfuric acid, and the remaining waste residue is phosphogypsum clinker.The application not only can reduce the cost of mine filling mining, but also is beneficial to reduce the pollution of phosphogypsum accumulation to the surface environment, promote the resource utilization of phosphogypsum, avoid resource waste, and ensure safe and efficient mining of mine.

Description

TECHNICAL FIELD

[0001] The application relates to a phosphogypsum-sulfuric acid co-production mine filling cementing material and a filling method, and belongs to the technical field of mine backfilling. BACKGROUND

[0002] With the rapid development of China's economic construction, the requirement for environmental protection is also continuously improved, and the overall demand of the resource development industry at the present stage is to comprehensively implement green mining technology in various mines. Filling mining is an important technical means to realize green mining of mines, but the main problem is high cost. In recent years, extensive exploration has been carried out at home and abroad to solve this problem, but the main focus is still on filling materials, especially how to use tailings, phosphogypsum, tunneling waste rock and the like generated by the industry as filling materials. Cement has good performance as a filling cementing material, but the price is relatively high, and many mines are still looking for substitutes, such as fly ash, ultrafine powder and the like, but due to the influence of the strength of the cementing body, they cannot completely replace cement. Finding new materials that can completely replace cement and have appropriate cost has become a technical problem to be solved in filling mining. SUMMARY

[0003] The purpose of the present application is to provide a phosphogypsum-sulfuric acid co-production mine filling cementing material, which helps to improve the utilization rate of phosphogypsum, reduce the pollution of phosphogypsum accumulation to the surface environment, promote the resource utilization of phosphogypsum, reduce the cost of filling mining, and ensure the coordinated development of mine exploitation and surrounding environment protection.

[0004] To solve the above technical problems, the application adopts the following technical scheme:

[0005] A phosphogypsum-sulfuric acid co-production mine filling cementing filling method, which uses phosphogypsum clinker and other materials as raw materials, and the weight ratio of the phosphogypsum clinker and the other materials is 1:4 to 10, wherein the other materials refer to tailings and waste rock; sulfur dioxide generated by heating and decomposing the phosphogypsum is used to prepare sulfuric acid, and the remaining waste residue is the phosphogypsum clinker.

[0006] In the aforementioned phosphogypsum-sulfuric acid co-production mine filling cementing filling method, the phosphogypsum clinker contains: at least 55% of tricalcium silicate by weight, at least 37% of calcium iron stone by weight, at least 1.5% of gypsum by weight, and at least 0.2% of halite by weight, wherein the chemical formula of the tricalcium silicate is O 30 Ca 18 Si6, the chemical formula of the calcium iron stone is Ca8Fe 4.36 Al 3.64 O 20 , the chemical formula of the gypsum is Ca4S4O 24 H 16 , and the chemical formula of the halite is O 30 Ca18 Si6.

[0007] The phosphogypsum-made sulfuric acid co-production mine filling cementation filling method of the preceding embodiment, wherein the tailings include the following raw materials in parts by weight: 859 parts of P2O5, 1542 parts of MgO, 3534 parts of CaO, 401 parts of SiO2, 63 parts of Fe2O3, and 77 parts of Al2O3; the waste rock has a particle size of less than or equal to 10 mm, and includes the following raw materials in parts by weight: 632 parts of P2O5, 1394 parts of MgO, 3214 parts of CaO, 746 parts of SiO2, 149 parts of Fe2O3, and 252 parts of Al2O3.

[0008] The phosphogypsum-made sulfuric acid co-production mine filling cementation filling method of the preceding embodiment, wherein the following is included: the raw materials and water are mixed, the mixed materials are stirred at a rotation speed of 200 r / min to 400 r / min for 20 to 40 min, and then are transported to the mine room designed for filling through a pipeline to perform layered filling.

[0009] The phosphogypsum-made sulfuric acid co-production mine filling cementation filling method of the preceding embodiment, wherein the following method is used for verification:

[0010] The phosphogypsum clinker and the other materials are mixed at a ratio of 1:4, 1:6, 1:8, and 1:10 respectively to form cementation materials, the formed cementation materials and the mine tailings are mixed, water is added and stirred for 20 to 40 min to form a tailings slurry; the pH value, the ambient temperature, and the humidity of the tailings slurry are measured and recorded;

[0011] A filling branch pipe is laid to the experimental mine room to be filled, a blocking wall is used to block the bottom entry of the experimental mine room, and a bleeding pipe is finally arranged;

[0012] The experimental mine room is filled by using a conventional filling method; the tailings slurry is repeatedly added for 3 to 5 times until the slurry stops bleeding and the mold is filled, different labels are made for each mold piece, the ambient temperature is controlled to place the entire filling body in a standard curing room with a temperature of 13±1℃ and a humidity of 71.5±1.5%, and the curing time is 7 days, 14 days, and 28 days respectively; during this period, the conditions of the test blocks, the initial setting time of the mold pieces, and the temperature and humidity of the filling station test area are recorded;

[0013] After curing for 28 days, the clinker filling body is cored and its compressive strength is detected to confirm whether the compressive strength can meet the filling requirements;

[0014] After the rock core is crushed and soaked in water for 72 hours, a water sample is collected and sent to a laboratory for pH value detection to confirm whether the index meets the index of a general solid waste.

[0015] Compared with the prior art, the application not only can reduce the mining cost of mine filling, but also is beneficial to reducing the pollution of phosphogypsum accumulation to the surface environment, promoting the resource utilization of phosphogypsum, avoiding resource waste, and ensuring safe and efficient mining of the mine. DETAILED DESCRIPTION

[0016] Embodiment 1 of the application: a phosphogypsum-based method for producing sulfuric acid and cement filling of mine filling, raw materials used include phosphogypsum clinker and other materials, the weight ratio of the phosphogypsum clinker and the other materials is 1:4 to 10, the other materials refer to tailings and waste rock; the sulfur dioxide produced after heating and high-temperature decomposition of the phosphogypsum is used for producing sulfuric acid, and the remaining waste residue is the phosphogypsum clinker.

[0017] The phosphogypsum clinker contains, by weight, at least 55% of tricalcium silicate, at least 37% of calcium iron stone, at least 1.5% of gypsum, and at least 0.2% of halite, the chemical formula of the tricalcium silicate is O 30 Ca 18 Si6, the chemical formula of the calcium iron stone is Ca8Fe 4.36 Al 3.64 O 20 , the chemical formula of the gypsum is Ca4S4O 24 H 16 , and the chemical formula of the halite is O 30 Ca 18 Si6. The main element content of the phosphogypsum clinker is shown in Table 1.

[0018] Al2O3 As2O3 BaO CaO CoO Cr2O3 4.88 0.01 0.28 >60 0.01 0.03 CuO [TFe2O3] K2O MgO MnO Na2O 0.01 3.01 0.31 0.61 0.03 0.16 NiO P2O5 PbO SiO2 SnO2 SO3 0.01 1.83 0.02 20.11 0.01 4.14 SrO TiO2 [V2O5] ZnO ZrO2 LOI 1000 0.16 0.42 0.01 0.03 0.04 0.25

[0019] Table 1: Main element content (%)

[0020] The tailings are discarded tailings produced after phosphorite beneficiation, and the material composition mainly includes dolomite, quartz, magnesium carbonate, calcite, etc., the tailings include the following raw materials by weight: 859 parts of P205, 1542 parts of MgO, 3534 parts of CaO, 401 parts of SiO2, 63 parts of Fe2O3, and 77 parts of Al2O3; the particle size of the waste rock is less than or equal to 10 mm, and the main component of the waste rock is dolomite, and specifically includes the following raw materials by weight: 632 parts of P205, 1394 parts of MgO, 3214 parts of CaO, 746 parts of SiO2, 149 parts of Fe2O3, and 252 parts of Al2O3.

[0021] The filling method specifically includes the following contents: the raw materials and water are mixed, the mixed materials are stirred at a rotation speed of 200 r / min to 400 r / min for 20 to 40 min, and then are transported to the mine chamber designed for filling through a pipeline to perform layered filling.

[0022] The output results of the present filling method are verified by the following method:

[0023] The phosphogypsum clinker and the other materials are mixed in a ratio of 1:4, 1:6, 1:8, and 1:10 respectively to prepare cementitious materials, and the filling station feeding parameters are adjusted according to the mixing ratio that meets the strength of 1.5 MPa, the concentration of 71%, and good pumpability, and then the filling material is prepared; the prepared cementitious material and the mine tailings are mixed, and water is added for stirring for 20-40 min to prepare a tailings slurry; the pH value, the environmental temperature, and the humidity of the tailings slurry are measured and recorded;

[0024] The filling branch pipe is laid to the experimental mine house to be filled, and then the bottom entry of the experimental mine house is blocked by a blocking wall, and finally a bleeding pipe is arranged;

[0025] The experimental mine house is filled by using a conventional filling method; the slurry is repeatedly rested and added with tailings slurry for 3-5 times until the slurry stops bleeding and fills the test mold, and different labels are made for each mold piece; the environmental temperature is controlled to place the entire filling body in a standard curing room with a temperature of 13±1℃ and a humidity of 71.5±1.5%, and the curing time is 7 days, 14 days, and 28 days respectively; during this period, the conditions of the test block, the initial setting time of the mold piece, and the temperature and humidity of the filling station test area are recorded;

[0026] When the ratio of the phosphogypsum clinker to the other materials in the mine filling cementitious material is 1:4, 1:6, 1:8, and 1:10 respectively, the strength of the cementitious filling material is shown in Table 2.

[0027] Serial number Proportion Sinking rate 7 days (MPa) 14 days (MPa) 28 days (MPa) 1 1:4 91％ 0.85 1.63 3.25 2 1:6 93％ 0.76 1.32 2.86 3 1:8 92％ 0.54 1.08 1.87 4 1:10 90％ 0.45 0.56 1.51

[0028] Table 2: Strength test values of cementitious filling materials (%)

[0029] The settlement rate of the filling body is measured according to the full load filling height-(7-day / 14-day / 28-day filling height) / full load filling height*100%, and the bleeding rate, the slump, the fluidity, the pressure area, and the compressive strength of the filling body are measured. The final filling body needs to meet various parameter requirements, i.e., the settlement rate is 9%, the bleeding rate is 10%, the slump is 12 cm, and the compressive strength is ≥1.5 MPa;

[0030] After 28 days of curing, the clinker filling body is cored and its compressive strength is detected to confirm whether it can meet the filling requirements;

[0031] After the core is evenly crushed, it is soaked with water for 72 hours, water samples are collected and sent to the laboratory for pH value detection to confirm whether the indicators meet the general solid waste indicators of the first category. In this embodiment, the average pH value of the water sample sent to the laboratory for detection is 8, which is weak alkaline, and the indicators all meet the general solid waste indicators of the first category (including the total phosphorus characteristic pollutant indicator 0.143 mg / L).

[0032] In this industrial experiment stage, 11 ore rooms were filled with 98397 cubic meters, and 16559.67 tons of clinker were consumed. Core sampling and detection were performed on the industrial experiment rooms. The 7-28 day compressive strength was between 0.99-9.29 MPa, and the filling ratio was 1:4. The 28-day core compressive strength of the filling body far exceeded the compressive strength of the original cement as a cementitious material. The average compressive strength of cement as a cementitious material was 2.14 MPa, and the average compressive strength of clinker as a cementitious material was 3.48 MPa, with a maximum of 9.29 MPa.

Claims

1. A method for co-production of sulphuric acid and mine filling cementitious fill from phosphogypsum, characterized by, The raw materials include phosphogypsum clinker and other materials, the weight ratio of the phosphogypsum clinker and other materials is 1:4 to 10, the other materials refer to tailings and waste rock; the sulfur dioxide produced by heating and high-temperature decomposition of the phosphogypsum is used for preparing sulfuric acid, and the remaining waste residue is the phosphogypsum clinker; the raw materials and water are mixed, the mixed materials are stirred at a rotating speed of 200 r / min to 400 r / min for 20 to 40 min, and then are conveyed to the mine house designed for filling by pipelines to carry out layered filling; The phosphogypsum clinker contains: at least 55% of tricalcium silicate by weight, at least 37% of calcium iron stone by weight, at least 1.5% of gypsum by weight, and at least 0.2% of halite by weight; The tailings include the following raw materials by weight: 859 parts of P2O5, 1542 parts of MgO, 3534 parts of CaO, 401 parts of SiO2, 63 parts of Fe2O3, and 77 parts of Al2O3; the particle size of the waste rock is less than or equal to 10 mm, and the waste rock includes the following raw materials by weight: 632 parts of P2O5, 1394 parts of MgO, 3214 parts of CaO, 746 parts of SiO2, 149 parts of Fe2O3, and 252 parts of Al2O3.

2. A method for producing sulphuric acid and simultaneously filling a mine with cementitious filling material from phosphogypsum according to claim 1, characterized in that The following method is used for verification: The phosphogypsum clinker and the other materials are mixed in a ratio of 1:4, 1:6, 1:8 and 1:10 respectively to prepare cementitious materials, the prepared cementitious materials and mine tailings are mixed, water is added and stirred for 20 to 40 min to prepare tailings slurry; the pH value of the tailings slurry, the environmental temperature and humidity are measured and recorded; The filling branch pipe is laid to the experimental mine house to be filled, the bottom entry of the experimental mine house is blocked by a blocking wall, and a bleeding pipe is finally arranged; The experimental mine house is filled by using a conventional filling method; the tailings slurry is repeatedly added for 3 to 5 times until the slurry stops bleeding and the mold is filled, different labels are made for each module, the environmental temperature is controlled to place the entire filling body in a standard curing room with a temperature of 13±1℃ and a humidity of 71.5±1.5% for curing, and the curing time is 7 days, 14 days and 28 days respectively, during which the conditions of the test block, the initial setting time of the module, and the temperature and humidity of the filling station test area are recorded; After curing for 28 days, the clinker filling body is cored and its compressive strength is detected to confirm whether the compressive strength can meet the filling requirements; After the rock core is crushed and soaked in water for 72 hours, the water sample is collected and sent to the laboratory for pH value detection to confirm whether the index meets the index of a general solid waste.