Red mud utilization method based on co-processing of industrial exhaust gas, sewage treatment and environment-friendly and high performance civil functional material

Abstract

A red mud utilization method based on co-processing of industrial exhaust gas, sewage treatment and an environment-friendly and high-performance civil functional material, belongs to the technical field of environmental science and cementitious material preparation, and relates to a preparation process of a solid waste-based cementitious material, specifically including the steps: preparing an environment-friendly and high-performance red mud-based civil functional material by using slag obtained after sewage treatment with red mud and other solid wastes in physical and chemical activation and high-temperature calcination methods. The compressive strength of a solid waste-based cementitious material prepared by using the method can reach 29 MPa, the leaching quantity (lower than 3.0 ppm) of toxic elements such as heavy metals is far lower than the national standard requirement, and a solid waste-based cementitious material with great performance can be prepared.

Claims

1. A red mud-based environment-friendly and high-performance civil functional cementitious material, comprising the following raw materials in parts by weight: 10-90 parts of slag obtained after sewage treatment with red mud, 20-60 parts of a cementing agent, 2-8 parts of an activator, and 1-5 parts of a toxic element curing agent; wherein a preparation method of the slag obtained after sewage treatment with red mud comprises the steps: carbonizing red mud with industrial exhaust gas, preparing the carbonized red mud into a sewage treatment agent, treating sewage, and collecting the slag obtained after sewage treatment with red mud.

2. The red mud-based environment-friendly and high-performance civil functional cementitious material according to claim 1, wherein the carbonization treatment has a pressure of 0.4-1.5 MPa, a carbonization temperature of 60-200 C., and a carbonization time of 6-24 hours, and the industrial exhaust gas is one of exhaust gas of a power plant, exhaust gas of an iron and steel industry and exhaust gas of a building material industry.

3. The red mud-based environment-friendly and high-performance civil functional cementitious material according to claim 1, wherein the red mud-based sewage treatment agent comprises the following raw materials in parts by weight: 60-100 parts of carbonized red mud, 0-20 parts of an enhancer, and 3-5 parts of a surfactant.

4. The red mud-based environment-friendly and high- performance civil functional cementitious material according to claim 1, comprising the following raw materials in parts by weight: 10-50 parts of slag obtained after sewage treatment with red mud, 20-40 parts of a cementing agent, 2-5 parts of an activator, and 1-3 parts of a toxic element curing agent.

5. The red mud-based environment-friendly and high-performance civil functional cementitious material according to claim 1, wherein the cementing agent is one or more of Portland cement, sulfoaluminate cement, ferroaluminate cement, magnesium phosphate cement, and aluminate cement.

6. The red mud-based environment-friendly and high-performance civil functional cementitious material according to claim 1, wherein the toxic element curing agent comprises a metal organic framework material, bentonite, fly ash, hydrotalcite, amino carboxylic acid or a polyamine chelating agent.

7. The red mud-based environment-friendly and high-performance civil functional cementitious material according to claim 1, comprising the following raw materials in parts by weight: 50-90 parts of slag obtained after sewage treatment with red mud, 40-60 parts of a cementing agent, 5-8 parts of an activator, and 3-5 parts of a toxic element curing agent.

8. The red mud-based environment-friendly and high-performance civil functional cementitious material according to claim 1, wherein the activator is one or more of hydroxide, silicate, sulfate, carbonate and phosphate.

9. A red mud utilization method based on co-processing of industrial exhaust gas, sewage treatment and an environment-friendly and high-performance civil functional material, comprising the steps: carbonizing red mud with industrial exhaust gas, preparing the carbonized red mud into a sewage treatment agent, treating sewage, and collecting slag obtained after sewage treatment with red mud; and uniformly mixing the slag obtained after sewage treatment with red mud and other solid wastes and performing calcination and grinding to obtain a high-performance cementitious material.

10. The red mud utilization method based on co-processing of industrial exhaust gas, sewage treatment and an environment-friendly and high-performance civil functional material according to claim 8, wherein the uniformly mixing comprises wet mixing.

11. The red mud utilization method based on co-processing of industrial exhaust gas, sewage treatment and an environment-friendly and high-performance civil functional material according to claim 9, wherein conditions for the calcination comprise heating to 1,350-1,400 C., heat preservation for 2.5-3 hours and cooling.

12. The red mud utilization method based on co-processing of industrial exhaust gas, sewage treatment and an environment-friendly and high-performance civil functional material according to claim 9, wherein the grinding is performed until a specific surface area is 300-320 m.sup.2/kg.

13. Application of the red mud-based environment-friendly and high-performance civil functional cementitious material according to claim 1 in construction of roads, bridges, underground projects or buildings.

Description

DETAILED DESCRIPTION

(1) It should be noted that the following detailed descriptions are all exemplary and are intended to provide a further understanding of this application. Unless otherwise indicated, all technical terms and scientific terms used in this application have the same meaning as commonly understood by a person of ordinary skill in the technical field to which this application belongs.

(2) It should be noted that terms used herein are only for describing specific implementations and are not intended to limit exemplary implementations according to the present application. As used herein, the singular form is also intended to include the plural form unless the context clearly dictates otherwise. In addition, it should further be understood that, terms comprise and/or include used in this specification indicate that there are features, steps, operations, devices, components, and/or combinations thereof.

(3) As introduced in the related art, in order to solve the problem of difficult treatment of industrial exhaust gas, industrial solid wastes such as red mud and sewage, the present invention provides a method for preparing an environment-friendly civil functional material by using slag obtained after sewage treatment with red mud.

(4) On the one hand, industrial exhaust gas is used to perform carbonization treatment on red mud to prepare a red mud-based sewage treatment agent first, and then a red mud-based high-performance civil functional cementitious material includes 10-90 parts of slag obtained after sewage treatment with red mud, 20-60 parts of a cementing agent, 2-8 parts of an activator, and 1-5 parts of a toxic element curing agent. On the other hand, the slag obtained after sewage treatment with red mud and other solid wastes are subjected to high-temperature calcination to prepare a high-performance cementitious material including 50-60 parts of red mud, 20-40 parts of steel slag, 10-30 parts of desulfurized gypsum, and 5-20 parts of calcium carbide slag.

(5) The red mud used to treat sewage may be Bayer red mud, sintered red mud and combined red mud.

(6) The treated sewage may be industrial wastewater, domestic sewage and agricultural wastewater.

(7) The cementing agent may be one or more of Portland cement, sulfoaluminate cement, ferroaluminate cement, magnesium phosphate cement, and aluminate cement.

(8) The activator is one or more of hydroxide, silicate, sulfate, carbonate, and phosphate.

(9) The toxic element curing agent includes a metal organic framework material, bentonite, fly ash, hydrotalcite, amino carboxylic acid, a polyamine chelating agent and the like.

(10) A calcination method includes wet mixing of various solid wastes, heating to 1,350 C., heat preservation for 3 hours, air cooling, natural cooling or water cooling to room temperature, and grinding until a specific surface area is 300 m.sup.2/kg.

(11) The technical solutions of this application are described below by using specific embodiments.

Embodiment 1

(12) Based on the first technical solution mentioned in the claims, a method for preparing an environment-friendly civil functional material by using slag obtained after sewage treatment with red mud included the following steps (herein a first step included preparation of raw materials, grinding and sieving, and a second step included blending of the raw materials and preparation of a material): (1) Bayer red mud was used, dried, ground and sieved with a 200-mesh sieve to prepare a slurry with a water-cement ratio of 1.0. (2) Carbonization parameters were adjusted: the pressure was 0.8 MPa, the temperature was 80 C., industrial exhaust gas of a power plant was used, and the carbonization time was 8 hours (to make the pH of the red mud reach 8). Then the red mud after carbonization treatment was dried, ground and sieved with a 300-mesh sieve for spare use. (3) A sewage treatment agent was prepared: 90 parts of red mud after carbonization treatment, 10 parts of fly ash, and 4 parts of cetyl ammonium bromide were thoroughly mixed for spare use. (4) The prepared red mud-based sewage treatment agent was used to treat high-salt wastewater in an iron and steel smelting process (the main chemical composition is shown in Table 1), and the red mud and the high-salt wastewater were mixed and stirred for 30 minutes (the dosing concentration was 50 g/L) and then subjected to suction filtration and drying for spare use.

(13) TABLE-US-00001 TABLE 1 Chemical composition of high-salt wastewater Ca.sup.2+ Cl.sup. SO.sub.4.sup.2 NO.sub.3.sup. COD (%) pH (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) value 34.4 130 0.28 12.7 69 7.82 (5) Slag obtained after sewage treatment with red mud, ordinary Portland cement, sodium silicate, and bentonite were dried to a moisture content of lower than 1%, ground and sieved with a 200-mesh sieve. (6) 60 parts of red mud, 20 parts of ordinary Portland cement, 10 parts of sodium silicate, and 6 parts of bentonite were weighed. Water was added until a water-cement ratio was 0.4. The mixture was stirred for 30 seconds and poured into a test mold. Parameters such as strength and the setting time were tested.

(14) A GBT 17671-1999 cement mortar strength test method was adopted for testing the strength. The leaching quantity of heavy metals was tested on the basis of GB/T 30810-2014. Performance indexes as shown in Table 2 are obtained according to a test method.

(15) TABLE-US-00002 TABLE 2 Performance test results Setting 3 d compressive 28 d compressive Leaching quantity of time strength strength heavy metals 8 h 20 s 9.6 MPa 18.6 MPa 2.9 ppm

Embodiment 2

(16) (1) Slag obtained after sewage treatment with red mud (same as that in Embodiment 1), granulated blast furnace slag, sodium silicate and bentonite were dried to a moisture content of lower than 1%, ground and sieved with a 200-mesh sieve.

(17) (2) 40 parts of red mud, 50 parts of granulated blast furnace slag, 10 parts of sodium hydroxide, and 5 parts of fly ash were weighed. Water was added until a water-cement ratio was 0.4. The mixture was stirred for 30 seconds and poured into a test mold. Parameters such as strength and the setting time were tested.

(18) A GBT 17671-1999 cement mortar strength test method was adopted for testing strength. The leaching quantity of heavy metals is tested on the basis of GB/T 30810-2014. Performance indexes as shown in Table 3 are obtained according to a test method.

(19) TABLE-US-00003 TABLE 3 Performance test results Setting 3 d compressive 28 d compressive Leaching quantity of time strength strength heavy metals 5 h 10 s 11.1 MPa 22.4 MPa 0.83 ppm

Embodiment 3

(20) (1) 50 parts of red mud, 25 parts of steel slag, 20 parts of desulfurized gypsum, and 10 parts of calcium carbide slag were weighed. Water was added until a water-cement ratio was 0.6. The mixture was mixed uniformly.

(21) (2) The mixed sample was calcined to 1,350 C. Heat preservation was performed for 3 hours. The mixed sample was dried after water cooling.

(22) (3) The calcined sample was ground to a specific surface area of 400 m.sup.2/kg. Water was added until a water-cement ratio was 0.4. The mixture was stirred for 30 seconds and poured into a test block. Parameters such as the test strength and the setting time were tested.

(23) A GBT 17671-1999 cement mortar strength test method was adopted for testing strength. The leaching quantity of heavy metals was tested on the basis of GB/T 30810-2014. Performance indexes as shown in Table 4 are obtained according to a test method.

(24) TABLE-US-00004 TABLE 4 Performance test results Setting 3 d compressive 28 d compressive Leaching quantity of time strength strength heavy metals 3 h 25 s 21.1 MPa 42.4 MPa 0.09 ppm

(25) It should be finally noted that the foregoing descriptions are merely preferred embodiments of the present invention, but are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for a person of ordinary skill in the art, modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent replacements can be made to some technical features in the technical solutions. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention. The specific implementations of the present invention are described above, but are not intended to limit the protection scope of the present invention. A person skilled in the art should understand that various modifications or deformations may be made without creative efforts based on the technical solutions of the present invention, and such modifications or deformations shall fall within the protection scope of the present invention.