Titanium gypsum solidified material and environmental risk assessment method thereof

Abstract

The application discloses a titanium gypsum solidification material and an environmental risk assessment method thereof. The titanium gypsum solidification material is obtained by mixing titanium gypsum produced in a titanium dioxide production process and red mud produced in an aluminum production process according to a weight ratio of 1:4-8 to form a titanium gypsum-red mud composite base material, and then performing reinforcing treatment on the titanium gypsum-red mud composite base material to obtain titanium gypsum-red mud composite granular material, and then mixing the titanium gypsum-red mud composite granular material with cement according to a weight ratio of 3:1-5. The titanium gypsum solidification material can realize waste resource utilization of the titanium gypsum and the red mud, realizes waste treatment by waste, and solves the problem of poor concrete compatibility of the titanium gypsum as cement ingredients, and provides a new high-strength material for roadbed material selection.

Description

Technical Field

[0001] This invention relates to the field of new materials technology, specifically to a titanium gypsum curing material and its environmental risk assessment method. Background Technology

[0002] Titanium gypsum is an industrial solid waste generated during the production of titanium dioxide. It mainly originates from the precipitate produced when alkaline substances such as limestone, lime, and carbide slag are added to neutralize acidic wastewater during the sulfuric acid process for titanium dioxide production. Its main component is calcium sulfate dihydrate (CaSO4·2H2O), and it also contains elements such as iron and silicon. Its color varies in complex ways, including green, yellow, and reddish-yellow, depending on the different valence states of iron. The particle size of titanium gypsum is generally 150–300 nm, and its water content is approximately 30–65%.

[0003] Although the applications of titanium gypsum are limited by issues such as moisture and color, it is more hygienic than other industrial gypsums. With proper processing, titanium gypsum can be used as a raw material in the cement industry to prepare cement retarders, gypsum bricks, and other building materials. It can also be used to produce building material gypsum, which is further used in the manufacture of paper-faced gypsum board, gypsum lines, decorative materials, plastering gypsum, gypsum blocks, and gypsum putty. However, the resource utilization of titanium gypsum still faces many challenges, such as environmental risks. Therefore, a titanium gypsum curing material and its environmental risk assessment method are needed to optimize the resource utilization of titanium gypsum. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a titanium gypsum curing material and its environmental risk assessment method.

[0005] The technical solution of the present invention is: a titanium gypsum curing material, wherein the titanium gypsum produced during the production of titanium dioxide and the red mud produced during the aluminum production process are mixed at a weight ratio of 1:4 to 8 to form a titanium gypsum-red mud composite matrix, and the titanium gypsum-red mud composite matrix is ​​reinforced to obtain titanium gypsum-red mud composite granules, and then the titanium gypsum-red mud composite granules are mixed with cement at a weight ratio of 3:1 to 5.

[0006] Note: Titanium gypsum is a precipitate mainly composed of calcium sulfate dihydrate (CaSO4·2H2O) produced when alkaline substances such as limestone, lime, and carbide slag are added to neutralize acidic wastewater during the sulfuric acid process for producing titanium dioxide. Titanium gypsum has a fine texture and a particle size much smaller than common industrial by-product gypsum such as desulfurization gypsum and phosphogypsum. It has good water retention properties and is weakly acidic.

[0007] Red mud is an industrial solid waste discharged during the extraction of alumina in the aluminum industry. Because of its high iron oxide content and appearance resembling red clay, it is called red mud. The particle diameter of red mud is generally 0.088–0.25 mm, with a specific gravity of 2.7–2.9, a bulk density of 0.8–1.0, and a melting point of 1200–1250℃. The main components of red mud include SiO2, CaO, Fe2O3, Al2O3, Na2O, and TiO2. The mineral composition of red mud is complex and does not conform to the mineral composition of natural soil. Furthermore, the chemical alkali bound to red mud is difficult to remove and is present in large quantities. It also contains fluorine, aluminum, and various other impurities. Its pH value is extremely high, remaining at 11.25–11.50 even after a 10-fold dilution (compared to above 12 in the original soil). It exhibits strong corrosiveness to biological materials, metals, and siliceous materials.

[0008] By using titanium gypsum curing materials to mix titanium gypsum and red mud, it is possible to treat waste with waste. This not only eliminates the problem of red mud alkalinity to a certain extent, but also solves the problem of poor compatibility of titanium gypsum as a cement ingredient with concrete. This provides a new high-strength material for the selection of roadbed materials, and enables the resource utilization of both titanium gypsum and red mud, realizing waste reuse.

[0009] Further, the strengthening treatment involves stirring the titanium gypsum-red mud composite matrix and spraying a matrix strengthening agent onto the titanium gypsum-red mud composite matrix during stirring. After thorough mixing, the matrix is ​​processed into spherical particles with a diameter of 10-20 mm. The amount of matrix strengthening agent sprayed is 300-500 mL / min per kg of titanium gypsum-red mud composite matrix.

[0010] Note: By using a binder enhancer, the mechanical properties of the mixture of titanium gypsum and red mud can be improved, thus acting as a reinforcing agent to enhance its compressive strength and durability. This makes the titanium gypsum-red mud composite binder more stable and reliable in application. Furthermore, the binder enhancer also plays a role in regulating the mixing temperature of the titanium gypsum-red mud composite binder.

[0011] Furthermore, the base material reinforcing agent is a sodium silicate-alginate mixture, wherein, by weight, the sodium silicate-alginate mixture consists of 10-20 parts sodium silicate, 5-10 parts alginate, and 80-120 parts water.

[0012] Note: By using a base reinforcement agent composed of sodium silicate and alginate, the crystal structure of titanium gypsum can be affected during use, thereby acting as an additive to improve the mechanical properties of titanium gypsum, enhance its compressive strength and durability, and thus make the subsequently prepared titanium gypsum cured material have better performance.

[0013] It should be noted that sodium silicate is corrosive and highly irritating, so temperature-controlled spraying is carried out using electronic equipment. If manual operation is required, protective glasses, gloves, and protective clothing must be worn to avoid direct contact with the skin and eyes, and the operating environment must be well-ventilated.

[0014] Furthermore, when applying the base material reinforcing agent, the temperature of the titanium gypsum-red mud composite base material is controlled between 15 and 40°C. Specifically, the temperature of the titanium gypsum-red mud composite base material is controlled by applying high-temperature and low-temperature base material reinforcing agents. When the temperature of the titanium gypsum-red mud composite base material reaches the threshold of 40°C or 15°C, the corresponding low-temperature or high-temperature base material reinforcing agent is used for temperature control. The temperature of the low-temperature base material reinforcing agent is 5 to 10°C, and the temperature of the high-temperature base material reinforcing agent is 80 to 90°C.

[0015] Explanation: By varying the temperature difference between the high-temperature zone (25-40℃) and the low-temperature zone (15-25℃), and continuously controlling the high and low temperature difference, a temperature difference is maintained between the sodium silicate-alginate mixture and the titanium gypsum and red mud. This improves the performance of the sodium silicate-alginate mixture, further improves the crystal morphology of the titanium gypsum, and enhances the performance of the titanium gypsum and red mud. This provides a base material for the subsequent preparation of titanium gypsum curing materials with excellent performance.

[0016] Furthermore, the method for mixing the titanium gypsum and red mud is to heat the titanium gypsum to 120-150°C, and then add it in batches to the red mud at room temperature for mixing and stirring.

[0017] Explanation: By heating titanium gypsum to the above-mentioned temperature range and mixing it with red mud at room temperature, the titanium gypsum can be rapidly cooled and better mixed with the red mud, which can further enhance the hardening strength of the titanium gypsum, thus obtaining a titanium gypsum curing material with excellent performance.

[0018] Furthermore, the addition is carried out in small batches multiple times. The method of adding in small batches multiple times is as follows: titanium gypsum is added to the red mud in 5 to 8 batches, and the temperature of the red mud is restored to room temperature after each batch before the next batch is added.

[0019] Note: Adding titanium gypsum in small batches multiple times can minimize the risk of rapid heating of the red mud, which could affect the mixing and bonding effect between the high-temperature titanium gypsum and the room-temperature red mud. By adding titanium gypsum in 5 to 8 batches, the mixing and bonding effect between titanium gypsum and red mud can meet the expected results without affecting production efficiency. Furthermore, using a water bath or reaction vessel to restore the temperature of the red mud helps to quickly return it to room temperature, thus reducing the interval between the addition of the next batch of titanium gypsum and improving production efficiency.

[0020] This invention also provides an environmental risk assessment method based on the above-mentioned titanium gypsum curing material, comprising the following steps:

[0021] S1. Assess the environmental risks of the titanium gypsum curing material as a building material:

[0022] After the titanium gypsum curing material is molded and cured, the leaching concentrations of copper, chromium and arsenic are tested to analyze whether the leaching concentrations of copper, chromium and arsenic are lower than the standard limits.

[0023] S2. Assess the environmental risks of using the titanium gypsum solidification material as solidified soil backfill:

[0024] The maximum content of manganese, copper, lead, nickel, mercury, arsenic, and cadmium in the titanium gypsum curing material was tested, and the analysis was conducted to determine whether the maximum content of these four elements was below the standard limit. Additionally, the leaching concentrations of zinc, iron, total arsenic, total selenium, total mercury, cadmium, lead, aluminum, fluoride, copper, manganese, and hexavalent chromium in the titanium gypsum curing material were tested, and the analysis was conducted to determine whether the leaching concentrations of these four elements were below the standard limit.

[0025] For pollutants not listed in building material standards and environmental quality standards, the requirements of document HJ 25.3-2019 should be given priority, and the assessment should be based on whether the risk value is acceptable.

[0026] Note: According to the "Technical Guidelines for Pollution Prevention and Control of Solid Waste Recycling" (HJ1091-2020), solid waste recycling products, when used as finished products, should meet the national, local, or industry-standard product quality requirements stipulated in GB34330, as well as the requirements of relevant national pollution control standards or technical specifications. These standards include the content standards of characteristic pollutants emitted into the environment during the production process and the content standards of characteristic pollutants in the product itself. This method can be used to propose corresponding risk assessment methods for titanium gypsum curing materials used as building materials and for solidified soil, enabling accurate assessment and analysis.

[0027] The beneficial effects of this invention are:

[0028] (1) The titanium gypsum curing material of the present invention can make resource utilization of titanium gypsum and red mud, and can make resource utilization of the two solid wastes of titanium gypsum and red mud, realize waste reuse, realize waste treatment, solve the problem of poor concrete compatibility of titanium gypsum as cement ingredient, and provide a new high-strength material for the selection of road subgrade materials.

[0029] (2) The titanium gypsum curing material of the present invention is prepared by using a base material reinforcing agent and temperature-controlled spraying to prepare titanium gypsum-red mud composite granules, which can improve the crystal morphology of titanium gypsum, enhance the performance of titanium gypsum and red mud, thereby improving the material strength and performance of the prepared titanium gypsum curing material.

[0030] (3) The environmental risk assessment method of the titanium gypsum curing material of the present invention can propose corresponding risk assessment methods for titanium gypsum curing material used as building material and for solidified soil, so as to conduct more accurate environmental risk assessment analysis. Detailed Implementation

[0031] The present invention will now be described in more detail with reference to specific embodiments, so as to better demonstrate the advantages of the present invention.

[0032] Example 1: A titanium gypsum curing material, which is made by mixing titanium gypsum produced during the production of titanium dioxide and red mud produced during the aluminum production process at a weight ratio of 1:6 to form a titanium gypsum-red mud composite matrix. The titanium gypsum-red mud composite matrix is ​​then reinforced to obtain titanium gypsum-red mud composite granules. These granules are then mixed with cement at a weight ratio of 3:1. It is understood that the ratio of titanium gypsum-red mud composite granules to cement can be adjusted according to actual usage requirements.

[0033] The strengthening treatment involves stirring the titanium gypsum-red mud composite matrix and spraying a matrix strengthening agent at 30°C onto the titanium gypsum-red mud composite matrix during stirring. After thorough mixing, the matrix is ​​processed into spherical particles with a diameter of 10-20 mm. The amount of matrix strengthening agent sprayed is 420 mL / min per kg of titanium gypsum-red mud composite matrix. The matrix strengthening agent is a sodium silicate-alginate mixture, which, by weight, consists of 16 parts sodium silicate, 7 parts alginate, and 110 parts water.

[0034] Setting up a comparison: Titanium gypsum curing material is made by mixing titanium gypsum produced during the production of titanium dioxide with red mud produced during the aluminum production process at a weight ratio of 1:6 to form a titanium gypsum-red mud composite matrix. The titanium gypsum-red mud composite matrix is ​​then granulated to obtain titanium gypsum-red mud composite granules. Finally, the titanium gypsum-red mud composite granules are mixed with cement at a weight ratio of 3:1.

[0035] The titanium plaster curing materials used in Example 1 and the control were molded and cured for 30 days, and their mechanical properties (unconfined compressive strength determination) were tested. The results are shown in Table 1 below:

[0036] Table 1 Unconfined compressive strength of RTC

[0037] Group 30d Example 1 13.7 MPa Comparison 11.9 MPa

[0038] As can be seen from the results in Table 1 above, the strength of the titanium gypsum curing material of the present invention can meet the requirements for road use, and titanium gypsum and red mud can be used as road materials. At the same time, it can be seen from the comparison with the control that the strength of the titanium gypsum curing material is significantly improved after the reinforcement treatment. Therefore, the titanium gypsum curing material of the present invention has better road use performance.

[0039] Example 2: This invention also provides an environmental risk assessment method for titanium gypsum curing materials, which includes the following steps, depending on the application scenario of the titanium gypsum curing material:

[0040] S1. Assess the environmental risks of titanium gypsum curing materials as building materials:

[0041] After the titanium plaster curing material is molded and cured (samples are prepared according to section 5.2 of GB / T 21372-2008), a leachate is prepared according to the method of GB / T 30810, and the leaching concentrations of copper, chromium, and arsenic are tested. Referring to Table 3 of GB 30760-2014, the leaching of lead, cadmium, arsenic, copper, zinc, nickel, chromium, and manganese is analyzed and evaluated. If the leaching concentrations of copper, chromium, and arsenic are below the standard limits, the risk is considered acceptable.

[0042] For example, using the titanium gypsum curing material from Example 1 as the test object, two measurements were conducted according to the method described above for "assessing the environmental risk of titanium gypsum curing material as a building material," and the test results are shown in Table 2 below:

[0043] Table 2 Detection Results

[0044]

[0045]

[0046] As shown in Table 2 above, the maximum leaching concentrations of copper, chromium, and arsenic were 0.01 mg / L, 0.03 mg / L, and 0.00796 mg / L, respectively, while lead, zinc, manganese, cadmium, and nickel were not detected. Compared with the standard limits specified in Table 3 of the "Technical Specification for Co-processing Solid Wastewater in Cement Kilns" (GB30760-2014) (i.e., the standard limits in Table 2), the leaching concentrations of copper, chromium, and arsenic in the titanium gypsum curing material of Example 1 were all lower than the corresponding standard limits.

[0047] Therefore, the submitted samples meet the pollution prevention and control technical requirements for the use of solid waste in building materials as stipulated in Article 6.3 of the "Technical Guidelines for Pollution Prevention and Control of Solid Waste Recycling" (HJ 1091-2020), namely, "the pollution control of the process of using solid waste to produce building materials such as bricks, tiles, lightweight aggregates, aggregates, glass, ceramics, ceramsite, and roadbed materials shall comply with the relevant industry pollutant emission standards, and the content of hazardous substances in the relevant products shall comply with the requirements of GB 30760."

[0048] S2. Assess the environmental risks of using titanium gypsum solidification material as solidified soil backfill:

[0049] For pollutants with limits set by building material standards and environmental quality standards, the evaluation standard for pollutant content in solidified soil should be selected from the second-class land use screening value standard in the "Soil Environmental Quality Standard for Construction Land Soil Pollution Risk Control (Trial)" (GB 36600-2018), taking into account the planning details of the titanium gypsum solidified land plot. Indicators not listed in GB 36600-2018 should be combined with local standards, as shown in Tables 3 and 4 below.

[0050] Table 3. Detection Indicators and Evaluation Standards (mg / kg)

[0051]

[0052] Table 4 Evaluation Standards for Heavy Metal Leaching (Class IV Limits in GB / T 14848-2017)

[0053] Serial Number Testing items Filter value Serial Number Testing items Filter value 1 cadmium 0.01 7 Zinc 5 2 Hexavalent chromium 0.1 8 manganese 1.5 3 mercury 0.002 9 selenium 0.1 4 copper 1.5 10 iron 2 5 lead 0.1 11 aluminum 0.5 6 arsenic 0.05 12 Fluorides 2

[0054] Specifically, for pollutants such as manganese, copper, lead, nickel, cadmium, arsenic, zinc, chromium, and heavy metals not specified in building material standards, their content is assessed with reference to GB 36600-2018. The maximum content of manganese, copper, lead, nickel, mercury, arsenic, and cadmium in titanium gypsum curing materials is tested, and it is analyzed whether the maximum content of manganese, copper, lead, nickel, mercury, arsenic, and cadmium is lower than the standard limit.

[0055] The leachate prepared according to the HJ / T 300 method was evaluated in accordance with GB / T 14848 and GB 3838; and the leaching concentrations of zinc, iron, total arsenic, total selenium, total mercury, cadmium, lead, aluminum, fluoride, copper, manganese and hexavalent chromium in the titanium gypsum curing material were tested, and it was analyzed whether the leaching concentrations of zinc, iron, total arsenic, total selenium, total mercury, cadmium, lead, aluminum, fluoride, copper, manganese and hexavalent chromium were lower than the standard limits.

[0056] For example, using the titanium gypsum curing material from Example 1 as the test object, two measurements were conducted according to the method described above for "assessing the environmental risk of using titanium gypsum curing material as solidified soil backfill." The test results are shown in Table 5 below.

[0057] Table 5 Test Results

[0058] Testing items unit (Example 1)-1 (Example 1)-2 Standard Limit copper mg / L ND ND 0.04 Zinc mg / L 0.212 0.265 0.009 iron mg / L 0.24 0.12 0.01 manganese mg / L ND ND 0.01 Total arsenic μg / L 5.4 7.2 0.3 Total selenium μg / L 0.6 0.8 0.4 Total Mercury μg / L 0.24 0.84 0.04 Hexavalent chromium mg / L ND ND 0.004 cadmium μg / L 4.79 0.12 0.05 lead μg / L 1.94 2.05 0.09 aluminum mg / L 0.092 0.299 0.009 sulfates mg / L 1740 1790 0.018 Fluorides mg / L 0.27 0.38 0.05 titanium μg / L 294 271 0.46

[0059] As shown in Table 5 above, the maximum leaching concentrations of zinc, iron, total arsenic, total selenium, total mercury, cadmium, lead, aluminum, and fluoride were 0.265 mg / L, 0.24 mg / L, 0.0072 mg / L, 0.0008 mg / L, 0.00084 mg / L, 0.00479 mg / L, 0.00205 mg / L, 0.299 mg / L, and 0.38 mg / L, respectively. Copper, manganese, and hexavalent chromium were not detected. Compared with the Class IV limits of GB / T 14848-2017, at this blending ratio, the leaching concentrations of zinc, iron, total arsenic, total selenium, total mercury, cadmium, lead, aluminum, fluoride, copper, manganese, and hexavalent chromium were all lower than the corresponding standard limits. Therefore, the submitted sample meets the requirements of the Class IV limits of GB / T 14848-2017.

[0060] For pollutants not listed in building material standards and environmental quality standards, such as titanium, the requirements of the "Technical Guidelines for Risk Assessment of Soil Pollution in Construction Land" (HJ 25.3-2019) should be prioritized, with the acceptable risk value as the basis for assessment. Test results show that the titanium content in the solidified soil ranges from 4620 to 8510 mg / kg, and the titanium concentration in the leachate ranges from 0.271 to 0.318 mg / L, as shown in Table 6 below.

[0061] Table 6. Titanium content and leaching (mg / kg)

[0062] category titanium CAS number 7440-32-6 Maximum content 8510mg / kg Maximum concentration of leachate 0.318 mg / L

[0063] An exposure assessment was conducted, as follows:

[0064] (1) Analyze the exposure scenario

[0065] Exposure scenarios refer to the situations in which pollutants from a land parcel migrate and reach the target population via different pathways under a specific land use pattern. Based on the activity patterns of people under different land use patterns, the "Technical Guidelines for Soil Pollution Risk Assessment of Construction Land" (HJ 25.3-2019) specifies exposure scenarios under two typical land use patterns: the first type of land use, represented by residential land (hereinafter referred to as "Category I land use"), and the second type of land use, represented by industrial land (hereinafter referred to as "Category II land use").

[0066] Based on the planning details of the titanium gypsum-stabilized land plots, and considering that adults have a long exposure period and high exposure frequency under the second type of land use, the carcinogenic risk and non-carcinogenic effects of pollutants are generally assessed based on adult exposure.

[0067] (2) Determine the exposure route

[0068] For Class II land use, the "Technical Guidelines for Soil Pollution Risk Assessment of Construction Land" (HJ 25.3-2019) specifies nine main exposure pathways and exposure assessment models, including six soil pollutant exposure pathways: oral ingestion of soil, skin contact with soil, inhalation of soil particulate matter, inhalation of gaseous pollutants from the top layer of soil in outdoor air, inhalation of gaseous pollutants from the lower layer of soil in outdoor air, and inhalation of gaseous pollutants from the lower layer of soil in indoor air; and three groundwater pollutant exposure pathways: inhalation of gaseous pollutants from groundwater in outdoor air, inhalation of gaseous pollutants from groundwater in indoor air, and drinking groundwater.

[0069] Taking into account the uses of building material chemical products, the exposure methods are determined as follows: oral ingestion of building material chemical products, skin contact with building material chemical products, inhalation of building material chemical product particulate matter, and drinking water from the area where the solidified soil is used for backfilling, as shown in Table 7:

[0070] Table 7 Exposure routes

[0071] Exposure routes titanium Oral ingestion of soil particulate matter √ Skin contact with soil particles √ Inhalation of soil particulate matter √ Inhaling gaseous pollutants from the topsoil in outdoor air / Inhaling gaseous pollutants from the lower soil layer in outdoor air. / Inhaling gaseous pollutants from groundwater in outdoor air / Inhaling gaseous pollutants from the underlying soil in indoor air / Gaseous pollutants from groundwater in indoor air / drinking groundwater √

[0072] Note: / indicates that the exposure pathway does not exist; we assume that the exposure pathway is through drinking groundwater.

[0073] (3) Determine the exposure route

[0074] a) Model parameters: Therefore, the values ​​of each model parameter are mainly based on the recommended values ​​in the "Technical Guidelines for Risk Assessment of Soil Pollution in Construction Land" (HJ 25.3-2019) and the "Technical Guidelines for Risk Assessment of Soil Pollution in Construction Land" (DB 33 / T 892-2022).

[0075] b) Calculation results

[0076] The exposure levels of pollutants of concern calculated using the exposure models and parameters recommended in the "Technical Guidelines for Risk Assessment of Soil Pollution in Construction Land" (HJ 25.3-2019) are shown in Table 8 below:

[0077] Table 8. Calculation of Exposure Levels

[0078]

[0079]

[0080] (4) Toxicity assessment and risk characterization

[0081] Based on the identified pollutants of concern in the risk assessment, and referring to the "Technical Guidelines for Risk Assessment of Soil Pollution in Construction Land" (HJ 25.3-2019) and the pollutant toxicity parameters provided in relevant databases, risk assessment toxicity parameters were obtained. Titanium is a non-carcinogenic pollutant, and its non-carcinogenic effect is characterized by a hazard quotient. The main tasks of risk characterization include calculating the carcinogenic and non-carcinogenic risks of a single pollutant, and calculating the carcinogenic and non-carcinogenic risks of all pollutants of concern. The main task of risk characterization is to use a risk assessment model, based on the dose-response relationship, to calculate the carcinogenic risk and hazard quotient of the pollutants of concern at the site, including the carcinogenic risk and hazard quotient of a single pollutant via a single pathway in groundwater, and the total carcinogenic risk and hazard index of a single pollutant in groundwater.

[0082] According to the Technical Guidelines for Soil Pollution Risk Assessment of Construction Land (HJ 25.3), the risk is unacceptable when the hazard quotient of a single pollutant exceeds 1.

[0083] Calculations show that the non-carcinogenic hazard quotients of titanium in titanium-stabilized soil and its leachate are 0.0127 and 1.66 × 10⁻⁶, respectively. -3 All values ​​are less than the limit of 1, as shown in Table 9. Therefore, the risk of titanium in titanium-stabilized soil is acceptable.

[0084] Table 9. Hazard Quotient Calculation Results

[0085] titanium Titanium gypsum solidified soil Leachate (groundwater) Maximum content 8510mg / kg / Maximum leaching concentration / 0.318 mg / L Non-carcinogenic risk from oral intake <![CDATA[4.43×10 -3 ]]> / Non-carcinogenic risk from skin contact <![CDATA[8.22×10 -3 ]]> / Cancer risk from inhaled particulate matter / / Cancer risk from drinking groundwater / <![CDATA[1.66×10 -3 ]]> total <![CDATA[1.27×10 -2 ]]> <![CDATA[1.66×10 -3 ]]>

[0086] Example 3: The difference between this example and Example 1 is that titanium gypsum produced during the titanium dioxide production process and red mud produced during the aluminum production process are mixed at a weight ratio of 1:4 to form titanium gypsum-red mud composite base material; titanium gypsum-red mud composite granules are mixed with cement at a weight ratio of 1:1.

[0087] Example 4: The difference between this example and Example 1 is that titanium gypsum produced during the titanium dioxide production process and red mud produced during the aluminum production process are mixed at a weight ratio of 1:8 to form titanium gypsum-red mud composite base material; titanium gypsum-red mud composite granules are mixed with cement at a weight ratio of 3:5.

[0088] Example 5: The difference between this example and Example 1 is that a base material reinforcing agent at 15°C was sprayed onto the titanium gypsum-red mud composite base material during stirring.

[0089] Example 6: The difference between this example and Example 1 is that a base material reinforcing agent at 40°C was sprayed onto the titanium gypsum-red mud composite base material during stirring.

[0090] Example 7: The difference between this example and Example 1 is that the amount of base material reinforcing agent sprayed is 300 mL / min per kg of titanium gypsum-red mud composite base material. The base material reinforcing agent is a sodium silicate-alginate mixture, which consists of 10 parts sodium silicate, 5 parts alginate and 80 parts water by weight.

[0091] Example 8: The difference between this example and Example 1 is that the amount of base material reinforcing agent sprayed is 500 mL / min per kg of titanium gypsum-red mud composite base material. The base material reinforcing agent is a sodium silicate-alginate mixture, which consists of 20 parts sodium silicate, 10 parts alginate and 120 parts water by weight.

[0092] To verify the influence of various parameters of the preparation method of titanium gypsum curing material of the present invention on the performance, control 1 was set up with a base material reinforcing agent consisting of 16 parts sodium silicate and 110 parts water, and control 2 with a base material reinforcing agent consisting of 7 parts alginate and 110 parts water.

[0093] The titanium plaster curing materials used in the above embodiments, Control 1, and Control 2 were molded and cured for 30 days, and their mechanical properties (unconfined compressive strength determination) were tested. The results are shown in Table 10 below:

[0094] Table 10 RTC Unconfined Compressive Strength

[0095] Group 30d Group 30d Example 3 13.6 MPa Example 7 12.8 MPa Example 4 12.5 MPa Example 8 13.8 MPa Example 5 13.1 MPa Comparison 1 12.2 MPa Example 6 13.4 MPa Comparison 2 12.0 MPa

[0096] As can be seen from the results in Table 10 above, changing the various parameters of the preparation method of titanium gypsum curing material has a certain impact on the strength of the titanium gypsum curing material in use. Specifically:

[0097] When the ratio of titanium gypsum to red mud is changed, the comparison results of Examples 3, 4 and 1 show that, based on Example 1, the titanium gypsum curing material prepared by reducing or increasing the amount of red mud added all showed a certain degree of decrease in strength. Therefore, the ratio of titanium gypsum to red mud in Example 1 is the best.

[0098] When the spraying temperature of the base material reinforcing agent is changed, the comparison results of Examples 5, 6 and Example 1 show that changing the spraying temperature has a certain impact on the reinforcing mixture of titanium gypsum and red mud. Based on Example 1, lowering or raising the spraying temperature resulted in a certain degree of decrease in the strength of the prepared titanium gypsum curing material. Therefore, the spraying temperature of the base material reinforcing agent in Example 1 is relatively optimal.

[0099] When the amount of base material reinforcing agent sprayed was changed, the comparison results between Examples 7, 8 and Example 1 showed that after reducing the amount of base material reinforcing agent sprayed based on Example 1, the prepared titanium gypsum cured material showed a significant decrease in strength in use. However, after increasing the amount of base material reinforcing agent sprayed based on Example 1, the prepared titanium gypsum cured material did not show a significant increase in strength in use. Therefore, from the perspective of economy, the amount of base material reinforcing agent sprayed in Example 1 is relatively optimal.

[0100] Meanwhile, the comparison results between Control 1, Control 2 and Example 1 show that when sodium silicate aqueous solution and alginate aqueous solution are used alone as base material reinforcing agents, the prepared titanium gypsum curing materials all show a significant decrease in strength. Therefore, the base material reinforcing agent prepared in this invention can effectively improve the performance of titanium gypsum curing materials.

[0101] Example 9: The difference between this example and Example 1 is that when spraying the base material reinforcing agent, the temperature of the titanium gypsum-red mud composite base material is controlled between 15 and 40°C. Specifically, the temperature of the titanium gypsum-red mud composite base material is controlled by spraying with high-temperature and low-temperature base material reinforcing agents. When the temperature of the titanium gypsum-red mud composite base material reaches the threshold of 40°C or 15°C, the corresponding low-temperature or high-temperature base material reinforcing agent is used for temperature control. The temperature of the low-temperature base material reinforcing agent is 8°C, and the temperature of the high-temperature base material reinforcing agent is 85°C.

[0102] Example 10: The difference between this example and Example 9 is that the temperature of the low-temperature base material reinforcing agent is 5°C, and the temperature of the high-temperature base material reinforcing agent is 90°C.

[0103] Example 11: The difference between this example and Example 9 is that the temperature of the low-temperature base material reinforcing agent is 10°C, and the temperature of the high-temperature base material reinforcing agent is 80°C.

[0104] To verify the effect of the above-mentioned temperature-controlled spraying method on the performance of titanium gypsum curing materials, the titanium gypsum curing materials of Examples 9, 10, and 11 were used for molding and curing for 30 days, and their mechanical properties (unconfined compressive strength determination) were tested. The results are shown in Table 11 below:

[0105] Table 11 Unconfined compressive strength of RTC

[0106] Group 30d Example 9 14.5 MPa Example 10 14.2 MPa Example 11 14.0 MPa

[0107] As can be seen from the results in Table 11 above, after optimizing the temperature-controlled spraying method, the strength of the materials used in Examples 9-11 is significantly better than that in Example 1. At the same time, by comparing the results of Examples 10, 11 and 9, it can be seen that when using base material reinforcing agents at different high and low temperatures for temperature-controlled spraying (i.e., different temperature differences), the strength of the titanium gypsum curing materials prepared in Examples 10 and 11 decreased. Therefore, the temperature-controlled spraying parameters of Example 9 are relatively optimal.

[0108] Example 12: The difference between this example and Example 1 is that the mixing method of titanium gypsum and red mud is as follows: the titanium gypsum is heated to 135°C, and then added to red mud at room temperature in batches for mixing and stirring; the batch addition adopts the method of adding small amounts multiple times. The method of adding small amounts multiple times is: the titanium gypsum is added to the red mud in 7 batches, and after each batch is added, the temperature of the red mud needs to be restored to room temperature before the next batch is added. It can be understood that the temperature of the reaction vessel containing the red mud is adjusted to restore it to room temperature of 25°C.

[0109] Example 13: The difference between this example and Example 1 is that the titanium plaster is heated to 120°C and added to the red mud in 8 batches.

[0110] Example 14: The difference between this example and Example 1 is that the titanium plaster is heated to 150°C and added to the red mud in 5 batches.

[0111] To verify the effect of the above-mentioned mixing method of titanium gypsum and red mud on the performance of titanium gypsum cured materials, the titanium gypsum cured materials of Examples 12, 13, and 14 were used for molding and curing for 30 days, and their mechanical properties (unconfined compressive strength determination) were tested. The results are shown in Table 12 below:

[0112] Table 12 Unconfined compressive strength of RTC

[0113] Group 30d Example 12 14.9 MPa Example 13 14.9 MPa Example 14 14.4 MPa

[0114] As can be seen from the results in Table 12 above, after mixing titanium gypsum and red mud at high temperature and rapid cooling, the strength of the materials in Examples 12-14 is significantly better than that in Example 1. At the same time, by comparing the results of Examples 13, 14 and 12, it can be seen that when titanium gypsum and red mud are mixed at different temperatures with high temperature and rapid cooling, the strength of the titanium gypsum cured materials prepared in Examples 13 and 14 decreases. Therefore, the heating temperature of titanium gypsum in Example 12 is relatively optimal.

Claims

1. A titanium plaster curing material, characterized in that, The titanium gypsum curing material is prepared by mixing titanium gypsum produced during the titanium dioxide production process with red mud produced during the aluminum production process at a weight ratio of 1:4 to 8 to form a titanium gypsum-red mud composite matrix. The titanium gypsum-red mud composite matrix is ​​then reinforced to obtain titanium gypsum-red mud composite granules. The titanium gypsum-red mud composite granules are then mixed with cement at a weight ratio of 3:1 to 5. The enhancement treatment involves stirring the titanium gypsum-red mud composite matrix and spraying a matrix reinforcement agent at 15-40°C onto the titanium gypsum-red mud composite matrix during stirring. After thorough mixing, the matrix is ​​processed into granules with a diameter of 10-20 mm. The amount of matrix reinforcement agent sprayed is 300-500 mL / min per kg of titanium gypsum-red mud composite matrix. The base material reinforcing agent is a sodium silicate-alginate mixture, wherein, by weight, the sodium silicate-alginate mixture consists of 10-20 parts sodium silicate, 5-10 parts alginate and 80-120 parts water.

2. The titanium plaster curing material as described in claim 1, characterized in that, When applying the base material reinforcing agent, control the temperature of the titanium gypsum-red mud composite base material between 15 and 40°C.

3. The titanium plaster curing material as described in claim 1, characterized in that, The method for mixing titanium gypsum and red mud is to heat the titanium gypsum to 120~150℃, and then add it to red mud at room temperature in batches for mixing and stirring.

4. The titanium plaster curing material as described in claim 3, characterized in that, The method of adding in small amounts multiple times is as follows: titanium gypsum is added to red mud in 5 to 8 batches, and the temperature of the red mud is restored to room temperature after each batch before adding the next batch.

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