CN116835881A - Method for preparing lime-iron garnet-based glass ceramic by utilizing iron-carbon-sulfur waste residues - Google Patents

Abstract

A method for preparing lime-iron garnet base glass ceramics by utilizing iron-carbon-sulfur waste residues belongs to the field of building material utilization of the iron-carbon-sulfur waste residues. The invention carries out raw material modification design, weighing, uniform mixing and limited melting on the iron-carbon-sulfur waste residues to form the modified base material. And crushing, screening, forming, grading, heat treatment, sintering and annealing the modified base material to obtain a series of iron-based crystallized samples. Exploring the crystal phase formation and crystal phase evolution rule of the iron-containing components in the waste residues to obtain the microcrystalline glass with controllable crystal phase types, morphology and size. According to the invention, the lime-iron garnet-based glass ceramic is obtained through high-temperature modification of the iron-carbon-sulfur waste residues and graded heat treatment fine regulation and control of the crystallization temperature of the modified base material, the high-value glass ceramic utilization target of the iron-carbon-sulfur waste residues is realized, the melting energy consumption is greatly reduced, the problems of melt overflow and early crystallization and porosity which are easy to occur in an iron-based system are avoided, the cost is saved, and the process safety is improved.

Description

A method for preparing calcium-iron garnet-based glass-ceramics using iron-carbon-sulfur waste residue

Technical Field

The present invention belongs to the technical field of resource utilization of smelting slag, and specifically, relates to a method for high-value microcrystalline vitrification of waste slag, and in particular, to a method for preparing andradite-based microcrystalline glass by utilizing iron-carbon-sulfur waste slag.

Background Art

Iron-carbon-sulfur waste slag is a waste slag mixture containing iron, carbon and sulfur elements discharged during the metal smelting process. The sources of iron, carbon and sulfur elements are different. For example, the auxiliary materials such as iron ore and fly ash added in the lead and zinc smelting process cause the discharged waste slag to contain iron and carbon elements, while the zinc sulfide ore phase in the zinc ore will cause the waste slag to contain mixed sulfur elements. According to statistics, the historical reserves of iron-carbon-sulfur waste slag exceed 200 million tons. In addition to conventional components such as CaO, FeO _x , SiO ₂ , Al ₂ O ₃ , MgO, etc., iron-carbon-sulfur waste slag also contains trace amounts of heavy metals such as Pd, Cd, Cr, etc. The large-scale storage of these waste slags not only wastes land resources, but also brings huge risks to the environment due to the leaching of heavy metals.

Waste slag building material is a mature and widely used waste slag resource utilization technology, including the use of waste slag to prepare cement, concrete, ceramics, etc., and microcrystalline glass technology is a relatively new technology for waste slag building material utilization. The development of this technology is not only conducive to the conversion of harmful waste slag into high-value microcrystalline glass, but also conducive to the effective solidification of heavy metals in the waste slag in the form of crystal phase and _{vitrification} . In the past, solid wastes such as tailings, blast furnace slag _{, steel slag, silicon slag, fly ash, etc. were used to prepare CaO-Al2O3-SiO2 (CAS), CaO-MgO-Al2O3-SiO2 ( CMAS ) and} other system microcrystalline glass. CN112340988A discloses a preparation method of CMAS system microcrystalline glass based on titanium-containing blast furnace slag itself _TiO2 as a nucleating agent. The _TiO2 of blast furnace slag itself is used as a nucleating agent to reduce the disposal cost of titanium-containing blast furnace slag in steel enterprises. CN110845144A discloses a method for vitrification of iron-captured waste catalyst smelting slag. Heavy metals such as _{Fe2O3 , Cr2O3} , _TiO2 , NiO, PbO in the smelting _slag are used as nucleating agents. The microcrystalline glass obtained after casting, rolling and crystallization can solidify the heavy metals in the smelting slag and avoid pollution.

Table 1 Preparation methods of some ferrosilicon alloys

In contrast, there are few reports on iron-carbon-sulfur waste slag-based microcrystalline glass with CaO-Fe ₂ O ₃ -SiO ₂ (CFS) as the main component. A key reason is that the iron-carbon-sulfur waste slag contains a large amount of FeO _x , C and S components, which easily cause serious overflow of the waste slag melt at high temperature and premature crystallization of the glass, and make the prepared microcrystalline glass have a large number of pores, resulting in poor physical and mechanical properties of the obtained microcrystalline glass. In order to solve the problem of FeO _x , smelting reduction method, ferrosilicon alloy preparation method, etc. have been developed to reduce the iron content in the waste slag and form secondary waste slag to prepare microcrystalline glass (Table 1). However, this method requires an additional melting step (working temperature such as 1450℃-1500℃) to reduce the FeO _x component in the waste slag to metallic iron or form ferrosilicon alloy. In addition, the remaining residue after iron selection needs to be melted and tempered at high temperature for a second time to prepare the re-dosed microcrystalline glass. Although this method can obtain additional pig iron or ferrosilicon alloy, the additional molten iron selection operation not only complicates the process flow, but also greatly increases the melting energy consumption and process cost required for preparing CFS-based microcrystalline glass.

In summary, how to develop a short-process, low-energy method for preparing low-porosity microcrystalline glass using iron-carbon-sulfur waste slag has become an urgent problem that technical personnel in this field need to solve.

Summary of the invention

The object of the present invention is to provide

1. In order to solve the above technical problems, the present invention provides a method for preparing calcium iron garnet-based microcrystalline glass using iron-carbon-sulfur waste residue. The preparation method has a short process and low energy consumption, and is easy to use iron-carbon-sulfur waste residue on a large scale in the preparation of low-porosity microcrystalline glass. To achieve the purpose of the present invention, the following technical scheme is adopted (Table 2):

Table 2 Preparation method of glass-ceramics of this patent

S1. The present invention provides a method for preparing calcium-iron garnet-based glass-ceramics using iron-carbon-sulfur waste slag, the method comprising the following steps:

(1) modifying and designing iron-carbon-sulfur waste slag to obtain a modified waste slag precursor;

(2) pre-treating and limiting heat treatment the modified waste slag precursor obtained in step (1) to melt and water quench to obtain a modified base material;

(3) The modified base material obtained in step (2) is first subjected to sintering pretreatment to obtain a base material green body, and then the green body is subjected to multi-step graded heat treatment to obtain a series of sintered samples including andradite-based microcrystalline glass.

In order to overcome the influence of the iron-carbon-sulfur components in the iron-carbon-sulfur waste slag on the process and obtain a short-process process, microcrystalline glass was prepared by focusing on waste slag modification and crystallization kinetics regulation. The temperature-induced phase transition and morphology evolution of the iron-rich component in the alkaline glass, as well as the influence of the FeOx component on the structure and properties of the microcrystalline glass were studied. The process of the present invention not only solves the problem of easy overflow of the high-temperature melt caused by the high FeOx component in the waste slag, reduces the safety hazards caused by large-scale production, but also avoids the possibility of premature crystallization of the base glass caused by the iron component in the waste slag, and eliminates the adverse effects of residual carbon and sulfides in the waste slag on the structure and properties of the microcrystalline glass, which is conducive to obtaining high-quality iron-rich microcrystalline glass.

Preferably, the modification design in step (1) is mainly based on the requirements of the CFS glass system, and the modified waste slag precursor raw materials are weighed according to the formula, including iron-carbon-sulfur waste slag and modified auxiliary materials, and the mass percentages thereof are 70-90:10-30 respectively, and the sum of the mass percentages of the iron-carbon-sulfur waste slag and the modified auxiliary materials is 100%;

The modified auxiliary materials in the present invention mainly include lead tailings, sodium carbonate, barium carbonate and clarifier, and the mass ratio thereof is 10-20:2-8:2-4:0.1-5;

Preferably, the lead tailings include components SiO ₂ , Al ₂ O ₃ , and Fe ₂ O ₃ , and the weight ratio thereof is 55-70:8-20:3-8; the lead tailings also include three or at least four of components CaO, Na ₂ O, K ₂ O, MgO, ZnO, TiO ₂ , and CuO, and the proportions of CaO, Na ₂ O, K ₂ O, MgO, ZnO, TiO ₂ , and CuO in the lead tailings are independently 0-5wt%, but excluding 0;

The clarifier includes one or two of CeO ₂ , Sb ₂ O ₃ , NaSbO ₃ and NaNO ₃ , and the proportions of CeO ₂ , Sb ₂ O ₃ , NaSbO ₃ and NaNO ₃ in the modified waste slag precursor raw material are independently 0.1-5 wt %.

Preferably, the iron-carbon-sulfur waste slag in step (1) comprises components SiO ₂ , Fe ₂ O ₃ , CaO, C, Al ₂ O ₃ , ZnO, MnO, CuO, Na ₂ O, MgO and SO ₃ , and the weight ratio of each component is 20-35:15-35:10-20:1-3:3-5:2-4:0.4-4:2-5:0.6-2:0.5-2:0.9-3;

The pretreatment in step (2) of the present invention comprises drying, ball milling, and multi-stage screening of the modified waste residue precursor;

Preferably, the drying temperature in step (2) is 120-160°C; the ball milling speed is 350-450rpm; the multi-stage screening includes first removing large rust impurities by a sieve method, and then fully ball milling the obtained modified waste residue precursor and then screening it twice; the screening particle size is 180-200 mesh.

The restrictive heat treatment melting in step (2) of the present invention is mainly carried out in a box furnace;

Preferably, the restrictive heat treatment temperature in step (2) is 1420-1450°C;

Preferably, the limiting heat treatment heating rate in step (2) is 8-10°C/min in the range of 30-300°C; 3-5°C/min in the range of 300-600°C; and 6-8°C/min in the range of 600-1450°C.

Preferably, in step (2), the holding time in the temperature range of 300-600° C. is 0.2-0.5 h, and the holding time in the temperature range of 1420-1450° C. is 1-2.5 h;

Preferably, the tail gas recovery in step (2) is a CO ₂ /SO _x tail gas recovery device;

Preferably, the temperature of water in the water quenching in step (2) is 15-30°C.

The sintering pretreatment in step (3) of the present invention comprises filtering, drying, ball milling and screening the modified base material; the drying temperature is 120-160° C.; the ball milling speed is 350-450 rpm; the screening particle size is 180-200 mesh;

Preferably, the multi-step graded heat treatment in step (3) is a sintering crystallization treatment of the base material green body, and 11 step temperature heat treatment conditions are set according to the thermal analysis curve, which are 130-160℃/1-2.5h, 400-500℃/1-2.5h, 550-600℃/1-2.5h, 650-750℃/1-2.5h, 780-810℃/1-2.5h, 850-900℃/1-2.5h, 1000-1020℃/1-2.5h, 1040-1060℃/1-2.5h, 1080-1110℃/1-2.5h, 1130-1160℃/1-2.5h and 1180-1200℃/1-2.5h;

In the present invention, the 11 step temperature heat treatments in step (3) are respectively carried out in a KSL1200 crystallization furnace;

Preferably, the modified base material in step (3) is subjected to multi-stage screening before heat treatment to obtain a modified base material of 180-200 meshes;

Preferably, in step (3), the heating rate of the 11 step temperature heat treatments at 30-500°C is 5-8°C/min; the heating rate at 500-750°C is 1-3°C/min; and the heating rate at 750-1200°C is 4-6°C/min.

S2. The preferred technical solution of the present invention comprises the following steps:

(1) weighing modified waste slag precursor raw materials according to the formula, including iron-carbon-sulfur waste slag, lead tailings, sodium carbonate, barium carbonate and clarifier, the mass percentages of which are 70-90:10-20:2-8:2-4:0.1-5 respectively, and the sum of the mass percentages of the modified waste slag precursor raw materials is 100%;

The iron-carbon-sulfur waste slag includes components SiO ₂ , Fe ₂ O ₃ , CaO, C, Al ₂ O ₃ , ZnO, MnO, CuO, Na ₂ O, MgO and SO ₃ , and the weight ratio of each component is 20-35:15-35:10-20:1-3:3-5:2-4:0.4-4:2-5:0.6-2:0.5-2:0.9-3;

The lead tailings include components SiO ₂ , Al ₂ O ₃ , and Fe ₂ O ₃ , and the weight ratio thereof is 55-70:8-20:3-8; the lead tailings also include three or at least four of components CaO, Na ₂ O, K ₂ O, MgO, ZnO, TiO ₂ , and CuO, and the proportions of CaO, Na ₂ O, K ₂ O, MgO, ZnO, TiO ₂ , and CuO in the lead tailings are independently 0-5wt%, but excluding 0;

The clarifier includes one or a combination of at least two of CeO ₂ , Sb ₂ O ₃ , NaSbO ₃ , and NaNO ₃ , and the proportions of CeO ₂ , Sb ₂ O ₃ , NaSbO ₃ , and NaNO ₃ in the modified waste slag precursor raw material are independently 0.1-5 wt %, but not including 0.

(2) Drying, ball milling, and multi-stage screening of the modified waste slag precursor raw material obtained in step (1); the drying temperature is 120-160°C; the ball milling speed is 350-450rpm; the multi-stage screening includes first removing large pieces of rust impurities by a sieve method, and then fully ball milling the obtained modified waste slag precursor and then screening it twice; the screening particle size is 180-200 mesh.

(3) The modified waste slag precursor raw material obtained after the treatment in step (2) is subjected to restricted heat treatment in a box furnace for melting, and then water quenching is performed to obtain a modified base material; the heat treatment temperature is 1420-1450°C; the restricted heat treatment heating rate is 8-10°C/min in the range of 30-300°C, 3-5°C/min in the range of 300-600°C, and 6-8°C/min in the range of 600-1450°C; the insulation time in the temperature zone of 300-600°C is 0.2-0.5h, and the insulation time in the temperature zone of 1420-1450°C is 1-2.5h; the water temperature used for water quenching is 15-30°C.

(4) filtering, drying, ball milling, multi-stage screening, and molding the modified base material obtained in step (3) to form a base material green body; drying temperature 120-160° C.; ball milling speed 350-450 rpm; screening particle size 180-200 mesh;

(5) subjecting the green body of the base material obtained in step (4) to multi-step graded heat treatment to obtain a series of sintered crystallized samples. According to the thermal analysis curve (DTA), 11 graded temperature heat treatment conditions are set, for example, 130-160°C/1-2.5h, 400-500°C/1-2.5h, 550-600°C/1-2.5h, 650-750°C/1-2.5h, 780-810°C/1-2.5h, 850-900°C/1-2.5h, 1000-1020°C/1-2.5h, 1040-1060°C/1-2.5h, 1080-1110°C/1-2.5h, 1130-1160°C/1-2.5h or 1180-1200°C/1-2.5h;

The 11 temperature-gradient heat treatments are controlled to have a heating rate of 5-8°C/min at a temperature of 30-500°C, a heating rate of 1-3°C/min at a temperature of 500-750°C, and a heating rate of 4-6°C/min at a temperature of 750-1200°C. After the base material green body is subjected to graded heat treatment, a series of sintered crystallized samples containing andradite-based microcrystalline glass are obtained.

S3. The present invention provides a microcrystalline glass prepared by the method described in the first aspect.

In the present invention, the main crystal phase of the microcrystalline glass is andradite and hematite, the secondary crystal phase is diopside and calcite, the volume density is 2.65-2.79g/ ^cm3 , the bending strength is 75-126MPa, the compressive strength is 625-890MPa, the Mohs hardness is 6-7, the acid resistance is 0.1-0.2%, the alkali resistance is 0.01-0.05%, and the water absorption rate is 0.01-0.06%.

S4. The present invention provides an application of the microcrystalline glass as described in S2 in the fields of architecture, metallurgy, machinery and chemical industry.

The principle of the present invention is as follows:

Based on the CaO-Fe ₂ O ₃ -SiO ₂ ternary phase diagram, andradite and hematite crystal phases can be formed according to the iron-carbon-sulfur waste slag components. The glass network often contains three components represented by SiO ₂ /Al ₂ O ₃ , CaO/MgO, and Na ₂ O/K ₂ O, among which SiO ₂ /Al2O3 is a glass network former, Na2O/K ₂ O is a glass network modifier or modified body, and CaO/MgO is a glass network intermediate. The main components of SiO2/Fe2O3 and a small amount of Al2O3 in the modified base material are used as glass formers. In order to adjust the process properties of the melt and meet the crystallization requirements, adjusting oxides Na ₂ O, BaO, lead tailings and clarifiers are added to the iron-carbon-sulfur waste slag. Among them, Na ₂ O mainly reduces the degree of polymerization and thermal stability of the glass network by forming sodium-oxygen ion bonds, and enhances the crystallization ability of the glass. In addition, the glass crystallization in the present invention mainly relies on the surface energy nucleation crystallization of a large number of particles in the modified base material, so that the particles have a certain creep property during the crystallization process to help the particles to achieve adhesion and sintering.

Compared with the prior art, the present invention has the following beneficial effects:

(1) The present invention uses iron-carbon-sulfur waste slag as the main raw material to prepare glass-ceramics, thereby realizing the high-value utilization of iron-carbon-sulfur waste slag and effectively alleviating the increasing land occupation and environmental pollution problems of iron-carbon-sulfur waste slag;

(2) The present invention adopts the modification reagent and the clarifier as the auxiliary raw materials for the preparation of iron-based microcrystalline glass according to the component characteristics of the CFS system and through the waste slag modification design, thereby eliminating the melting, high-temperature reduction, cooling, crushing and magnetic separation processes required for iron selection before preparing microcrystalline glass in the traditional process, and has the advantages of simple steps, low energy consumption and low cost; at the same time, it avoids the dust pollution containing trace heavy metals caused by the magnetic separation process;

(3) The present invention adopts a restrictive heat treatment measure of controlling the heating rate in different temperature zones during the melting stage of the modified waste slag precursor and the sintering crystallization stage of the modified base material, thereby avoiding the adverse effects of the iron element in the iron-carbon-sulfur waste slag on the melting and crystallization processes to the greatest extent; at the same time, it eliminates the possibility of carbon and sulfide gas generation due to high temperature, which aggravates the possibility of melt overflow and aggravates the porosity of the microcrystalline glass sample, thereby facilitating the acquisition of high-quality microcrystalline glass;

(4) The present invention prepares a series of sintered samples with different main crystal phases and different sintering shrinkage rates at different temperatures through restrictive heat treatment measures, studies the crystal phase evolution process of the iron-containing component in the waste slag under 11 heat treatment conditions, obtains the controllable preparation conditions of microcrystalline glass containing rare calcium iron garnet main crystal phase, and expands the path of high-value microcrystalline glass utilization of iron-carbon-sulfur waste slag; in addition, the evolution law of these iron-containing crystal phases can provide a reference for the future application of iron-carbon-sulfur waste slag in the field of magnetism;

(5) The main crystal phases of the microcrystalline glass prepared by the present invention are andradite and hematite, and the secondary crystal phases are diopside and calcite. The volume density is the highest at 2.79g/ ^cm3 , the bending strength is the highest at 126MPa, the compressive strength is the highest at 890Mpa, the Mohs hardness is the highest at 7, the acid resistance is the lowest at 0.1%, the alkali resistance is the lowest at 0.01%, and the water absorption rate is the lowest at 0.01%. The obtained microcrystalline glass has high mechanical strength and excellent corrosion resistance, and has great development prospects in the fields of construction, metallurgy, machinery, chemical industry, etc.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a process flow chart of preparing calcium-iron-based glass-ceramics using iron-carbon-sulfur waste slag provided by the present invention;

FIG2 is a PXRD diagram of the modified base material obtained in Example 1;

FIG3 is a DTA diagram of the base material green body obtained in Example 2;

FIG4 is a PXRD diagram of samples obtained after heating the modified base material of Example 1-11 at different temperatures;

FIG5 is a microscopic morphology of samples sintered under the temperature conditions of Comparative Example 6, Comparative Example 7, Example 2 and Comparative Example 8;

FIG6 is a diagram of the high temperature melt overflow obtained in Example 3;

FIG7 is a picture of the andradite-based glass-ceramics obtained in Example 2;

FIG. 8 is a picture of a sample with high porosity obtained in Example 3.

DETAILED DESCRIPTION

In order to better explain the present invention, the contents of the present invention are further illustrated below in conjunction with embodiments, but the present invention is not limited to the following embodiments.

Example 1

The present invention provides a method for preparing calcium-iron garnet-based glass-ceramics by using iron-carbon-sulfur waste residue, as shown in FIG1 , the method comprises the following steps:

(1) weighing modified waste slag precursor raw materials according to the formula, including iron-carbon-sulfur waste slag, lead tailings, sodium carbonate, barium carbonate and clarifier, the mass percentages of which are 70:20:6:2:2 respectively, and the sum of the mass percentages of the modified waste slag precursor raw materials is 100%;

The iron-carbon-sulfur waste slag includes components SiO ₂ , Fe ₂ O ₃ , CaO, C, Al ₂ O ₃ , ZnO, MnO, CuO, Na ₂ O, MgO and SO ₃ , and the weight ratio of each component is 33:31:18:3:4:3:0.4:2:1:0.6:3;

The lead tailings include components SiO ₂ , Al ₂ O ₃ , Fe ₂ O ₃ , CaO, Na ₂ O, K ₂ O, MgO, ZnO, TiO ₂ , and CuO, and the weight ratio thereof is 64:16:7:3:1:3:0.8:0.5:0.3:2;

The clarifier includes CeO ₂ and NaSbO ₃ , and the weight ratio of each component is 2:5.

(2) Drying, ball milling, and multi-stage screening of the modified waste slag precursor raw material obtained in step (1); drying temperature 140°C; ball milling speed 350rpm; multi-stage screening includes first removing large pieces of rust impurities by a sieve method, and then fully ball milling the obtained modified waste slag precursor and then screening it twice; the screening particle size is 180 mesh.

(3) The modified waste slag precursor raw material obtained after the treatment in step (2) is subjected to restricted heat treatment and melting in a box furnace, and then water quenching is performed to obtain a modified base material; the heat treatment temperature is 1450°C; the restricted heat treatment heating rate is 8°C/min in the 30-300°C range, 5°C/min in the 300-600°C range, and 8°C/min in the 600-1450°C range; the holding time of the 450°C temperature zone is separately set to 0.2h, and the holding time at 1430°C is 1h; the water temperature used for water quenching is 20°C.

(4) filtering, drying, ball milling, multi-stage screening, and molding the modified base material obtained in step (3) to form a base material green body; drying temperature 160° C.; ball milling speed 350 rpm; screening particle size 200 mesh;

(5) The base material green body obtained in step (4) is subjected to a multi-step graded heat treatment to obtain a series of sintered crystallized samples. According to the 11 graded temperature heat treatment conditions set according to the thermal analysis curve, the heat treatment conditions implemented in this embodiment are a heating temperature of 1050°C, a heating rate of 5°C/min, and a crystallization time of 1h. After the base material green body is heat treated, a sintered crystallized sample is obtained.

Example 2

The present invention provides a method for preparing calcium-iron garnet-based glass-ceramics by using iron-carbon-sulfur waste residue, as shown in FIG1 , the method comprises the following steps:

(1) weighing modified waste slag precursor raw materials according to the formula, including iron-carbon-sulfur waste slag, lead tailings, sodium carbonate, barium carbonate and clarifier, the mass percentages of which are 80:10:5:3:2 respectively, and the sum of the mass percentages of the modified waste slag precursor raw materials is 100%;

The iron-carbon-sulfur waste slag includes components SiO ₂ , Fe ₂ O ₃ , CaO, C, Al ₂ O ₃ , ZnO, MnO, CuO, Na ₂ O, MgO and SO ₃ , and the weight ratio of each component is 29:35:20:1:3:2:0.6:3:0.6:2:0.9;

The lead tailings include components SiO ₂ , Al ₂ O ₃ , Fe ₂ O ₃ , CaO, Na ₂ O, K ₂ O, MgO, ZnO, TiO ₂ , and CuO, and the weight ratio thereof is 65:15:6:4:2:2:1:0.3:0.5:2;

The clarifier includes CeO ₂ and NaNO ₃ , and the weight ratio of each component is 1:2.

(2) Drying, ball milling, and multi-stage screening of the modified waste slag precursor raw material obtained in step (1); drying temperature 150° C.; ball milling speed 400 rpm; multi-stage screening includes first removing large pieces of rust impurities by a sieve method, and then fully ball milling the obtained modified waste slag precursor and then screening it twice; the screening particle size is 180 mesh.

(3) The modified waste slag precursor raw material obtained after the treatment in step (2) is subjected to restricted heat treatment in a box furnace for melting, and then water quenching is performed to obtain a modified base material; the heat treatment temperature is 1450°C; the restricted heat treatment heating rate is 8°C/min in the range of 30-300°C, 3°C/min at 450°C, and 5°C/min in the range of 600-1450°C; the holding time of the 450°C temperature zone is separately set to 0.5h, and the holding time at 1450°C is 2h; the water temperature used for water quenching is 20°C.

(4) filtering, drying, ball milling, multi-stage screening, and molding the modified base material obtained in step (3) to form a base material green body; drying temperature 160° C.; ball milling speed 350 rpm; screening particle size 200 mesh;

(5) The base material green body obtained in step (4) is subjected to a multi-step graded heat treatment to obtain a series of sintered crystallized samples. According to the 11 graded temperature heat treatment conditions set according to the thermal analysis curve, the heat treatment conditions implemented in this embodiment are a heating temperature of 1050°C, a heating rate of 5°C/min, and a crystallization time of 1.2h. After the base material green body is heat treated, a sintered crystallized sample 8 is obtained (Figure 7).

Figure 2 is a PXRD diagram of the modified base material obtained in step (3) of this embodiment. It can be seen from Figure 2 that the modified waste slag precursor raw material has been completely melted to form a homogeneous glass phase. Figure 3 is a DTA diagram of the base material green body obtained in step (5) of this embodiment. It can be seen from Figure 3 that the base material green body has obvious crystallization exothermic peaks at 752°C, 835°C and 1104°C, respectively. Figure 7 is an optical image of the calcium iron garnet-based microcrystalline glass obtained in step (5) of this embodiment. It can be seen from Figure 7 that the surface of the sample obtained after the modified waste slag is melted and sintered and crystallized by restrictive heat treatment has no obvious porosity.

Example 3

The present invention provides a method for preparing calcium-iron garnet-based glass-ceramics by using iron-carbon-sulfur waste residue, as shown in FIG1 , the method comprises the following steps:

(1) weighing modified waste slag precursor raw materials according to the formula, including iron-carbon-sulfur waste slag, lead tailings, sodium carbonate, barium carbonate and clarifier, the mass percentages of which are 80:10:6:3:1 respectively, and the sum of the mass percentages of the modified waste slag precursor raw materials is 100%;

The iron-carbon-sulfur waste slag includes components SiO ₂ , Fe ₂ O ₃ , CaO, C, Al ₂ O ₃ , ZnO, MnO, CuO, Na ₂ O, MgO and SO ₃ , and the weight ratio of each component is 22:33:20:3:5:2:4:5:2:0.5:1;

The lead tailings include components SiO ₂ , Al ₂ O ₃ , Fe ₂ O ₃ , CaO, Na ₂ O, K ₂ O, MgO, ZnO, TiO ₂ , and CuO, and the weight ratio thereof is 65:14:5:5:1:3:1:0.3:0.4:1;

The clarifier includes CeO ₂ , Sb ₂ O ₃ and NaSbO ₃ , and the weight ratio of each component is 1:2:1.

(2) Drying, ball milling, and multi-stage screening of the modified waste slag precursor raw material obtained in step (1); drying temperature 120°C; ball milling speed 350rpm; multi-stage screening includes first removing large pieces of rust impurities by a sieve method, and then fully ball milling the obtained modified waste slag precursor and then screening it twice; the screening particle size is 180 mesh.

(3) The modified waste slag precursor raw material obtained after the treatment in step (2) is subjected to limited heat treatment and melting in a box furnace, and then water quenched to obtain a modified base material; the heat treatment temperature is 1450°C; the entire heating process maintains a constant heating rate of 8°C/min, and the insulation time at 1450°C is 2h; the water temperature used for water quenching is 20°C.

(4) filtering, drying, ball milling, multi-stage screening, and molding the modified base material obtained in step (3) to form a base material green body; drying temperature 160° C.; ball milling speed 350 rpm; screening particle size 200 mesh;

(5) The base material green body obtained in step (4) is subjected to a multi-step graded heat treatment to obtain a series of sintered crystallized samples. According to the 11 graded temperature heat treatment conditions set according to the thermal analysis curve, the heat treatment conditions implemented in this embodiment are a heating temperature of 1050°C, a heating rate of 5°C/min, and a crystallization time of 2h. After the base material green body is heat treated, a sintered crystallized sample is obtained (Figure 8).

FIG6 is an optical picture of the melt obtained in step (3) of this embodiment. As shown in FIG6, there is obvious overflow during the melting process of the modified waste slag after non-restrictive heat treatment, which brings unsafe factors to the experiment. FIG8 is an optical picture of the sintered sample obtained in step (5) of this embodiment. As shown in FIG6, there is obvious porosity on the surface of the sample obtained after the non-restrictive melted base material is sintered and crystallized.

Comparative Example 1

This comparative example provides a method for preparing calcium-iron garnet-based microcrystalline glass using iron-carbon-sulfur waste slag, and its steps are the same as those of Example 2 of the present invention, except that the conditions for sintering and crystallizing the basic green material are different, and the rest are the same as Example 2. According to the 11 step temperature heat treatment conditions set according to the thermal analysis curve, the heat treatment condition of Comparative Example 1 is 150°C/1.2h, and the obtained sintered sample is numbered as Sample 1.

The PXRD of the sample obtained in this example is shown in FIG4 , and its main crystalline phase is shown in Table 3 .

Comparative Example 2

This comparative example provides a method for preparing calcium-iron garnet-based microcrystalline glass using iron-carbon-sulfur waste slag, and its steps are the same as those of Example 2 of the present invention, except that the conditions for sintering and crystallizing the basic green material are different, and the rest are the same as Example 2. According to the 11 step temperature heat treatment conditions set according to the thermal analysis curve, the heat treatment condition of Comparative Example 1 is 450°C/1.2h, and the obtained sintered sample is numbered as Sample 2.

The PXRD of the sample obtained in this example is shown in FIG4 , and its main crystalline phase is shown in Table 3 .

Comparative Example 3

This comparative example provides a method for preparing calcium-iron garnet-based microcrystalline glass using iron-carbon-sulfur waste slag, and its steps are the same as those of Example 2 of the present invention, except that the conditions for sintering and crystallizing the basic green material are different, and the rest are the same as Example 2. According to the 11 step temperature heat treatment conditions set according to the thermal analysis curve, the heat treatment condition of Comparative Example 1 is 600°C/1.2h, and the obtained sintered sample is numbered as Sample 3.

The PXRD of the sample obtained in this example is shown in FIG4 , and its main crystalline phase is shown in Table 3 .

Comparative Example 4

This comparative example provides a method for preparing calcium-iron garnet-based microcrystalline glass using iron-carbon-sulfur waste slag, and its steps are the same as those of Example 2 of the present invention, except that the conditions for sintering and crystallizing the basic green material are different, and the rest are the same as Example 2. According to the 11 step temperature heat treatment conditions set according to the thermal analysis curve, the heat treatment condition of Comparative Example 1 is 745°C/1.2h, and the obtained sintered sample is numbered as Sample 4.

The PXRD of the sample obtained in this example is shown in FIG4 , and its main crystalline phase is shown in Table 3 .

Comparative Example 5

This comparative example provides a method for preparing calcium-iron garnet-based microcrystalline glass using iron-carbon-sulfur waste slag, and its steps are the same as those of Example 2 of the present invention, except that the conditions for sintering and crystallizing the basic green material are different, and the rest are the same as Example 2. According to the 11 step temperature heat treatment conditions set according to the thermal analysis curve, the heat treatment condition of Comparative Example 1 is 807°C/1.2h, and the obtained sintered sample is numbered as Sample 5.

The PXRD of the sample obtained in this example is shown in FIG4 , and its main crystalline phase is shown in Table 3 .

Comparative Example 6

This comparative example provides a method for preparing calcium iron garnet-based microcrystalline glass using iron-carbon-sulfur waste slag, and its steps are the same as those of Example 2 of the present invention, except that the conditions for sintering and crystallizing the basic green material are different, and the rest are the same as Example 2. According to the 11 step temperature heat treatment conditions set according to the thermal analysis curve, the heat treatment condition of comparative example 1 is 880°C/1.2h, and the obtained sintered sample is numbered as sample 6.

The PXRD of the sample obtained in this example is shown in FIG4 , and its main crystalline phase is shown in Table 3 .

Comparative Example 7

This comparative example provides a method for preparing calcium-iron garnet-based microcrystalline glass using iron-carbon-sulfur waste slag, and its steps are the same as those of Example 2 of the present invention, except that the conditions for sintering and crystallizing the basic green material are different, and the rest are the same as Example 2. According to the 11 step temperature heat treatment conditions set according to the thermal analysis curve, the heat treatment condition of Comparative Example 1 is 1010°C/1.2h, and the obtained sintered sample is numbered as Sample 7.

The PXRD of the sample obtained in this example is shown in FIG4 , and its main crystalline phase is shown in Table 3 .

Comparative Example 8

This comparative example provides a method for preparing calcium-iron garnet-based microcrystalline glass using iron-carbon-sulfur waste slag, and its steps are the same as those of Example 2 of the present invention, except that the conditions for sintering and crystallizing the basic green material are different, and the rest are the same as Example 2. According to the 11 step temperature heat treatment conditions set according to the thermal analysis curve, the heat treatment condition of Comparative Example 1 is 1100°C/1.2h, and the obtained sintered sample is numbered as Sample 9.

The PXRD of the sample obtained in this example is shown in FIG4 , and its main crystalline phase is shown in Table 3 .

Comparative Example 9

This comparative example provides a method for preparing calcium iron garnet-based microcrystalline glass using iron-carbon-sulfur waste slag, and its steps are the same as those of Example 2 of the present invention, except that the conditions for sintering and crystallizing the basic green material are different, and the rest are the same as Example 2. According to the 11 step temperature heat treatment conditions set according to the thermal analysis curve, the heat treatment condition of Comparative Example 1 is 1150°C/1.2h, and the obtained sintered sample is numbered as Sample 10.

The PXRD of the sample obtained in this example is shown in FIG4 , and its main crystalline phase is shown in Table 3 .

Comparative Example 10

This comparative example provides a method for preparing calcium-iron garnet-based microcrystalline glass using iron-carbon-sulfur waste slag, and its steps are the same as those of Example 2 of the present invention, except that the conditions for sintering and crystallizing the basic green material are different, and the rest are the same as Example 2. According to the 11 step temperature heat treatment conditions set according to the thermal analysis curve, the heat treatment condition of Comparative Example 1 is 1200°C/1.2h, and the obtained sintered sample is numbered as Sample 11.

The PXRD of the sample obtained in this example is shown in FIG4 , and its main crystalline phase is shown in Table 3 .

Table 3

The results of comparative examples 1 to 10 show that the shrinkage rate of the sample obtained under the heat treatment conditions in Example 2 is the largest, and the obtained sample is andradite-based microcrystalline glass. The analysis of the results in Table 3 shows that with the increase of the sintering crystallization temperature, the shrinkage of the sample first increases and then decreases.

In summary, the present invention uses iron-carbon-sulfur waste slag as the main raw material to prepare microcrystalline glass, realizes the high-value utilization of iron-carbon-sulfur waste slag, and effectively alleviates the increasing land occupation and environmental pollution problems of iron-carbon-sulfur waste slag. Based on the component characteristics of the CFS system and through the waste slag modification design, the present invention uses modification reagents and clarifiers as auxiliary raw materials for the preparation of iron-based microcrystalline glass, avoiding the melting, high-temperature reduction, cooling, crushing, and magnetic separation processes required for iron selection before preparing microcrystalline glass in traditional processes, and has the advantages of simple steps, low energy consumption, and low cost; at the same time, it avoids dust pollution containing trace heavy metals caused by the magnetic separation process. The present invention adopts restrictive heat treatment measures to control the heating rate in temperature zones during the melting stage of the modified waste slag precursor and the sintering crystallization stage of the modified base material, thereby avoiding the adverse effects of the iron element in the iron-carbon-sulfur waste slag on the melting and crystallization process to the greatest extent; at the same time, it eliminates the possibility of carbon and sulfide exacerbating melt overflow due to high-temperature gas production and increasing the porosity of the microcrystalline glass sample, which is conducive to obtaining high-quality microcrystalline glass. The present invention prepares a series of sintered samples with different main crystal phases and differential sintering shrinkage rates at different temperatures through restrictive heat treatment measures, obtains controllable preparation conditions for microcrystalline glass containing calcium iron garnet main crystal phase, and expands the path of high-value microcrystalline glass utilization of iron-carbon-sulfur waste slag. The main crystal phases of the microcrystalline glass prepared by the present invention are andradite and hematite, and the secondary crystal phases are diopside and calcite. The volume density is the highest at 2.79g/ ^cm3 , the bending strength is the highest at 126MPa, the compressive strength is the highest at 890Mpa, the Mohs hardness is the highest at 7, the acid resistance is the lowest at 0.1%, the alkali resistance is the lowest at 0.01%, and the water absorption rate is the lowest at 0.01%. The obtained microcrystalline glass has high mechanical strength and excellent corrosion resistance, and has great development prospects in the fields of construction, metallurgy, machinery, chemical industry, etc.

Claims (10)

1. A method for preparing andradite-based glass-ceramics using iron-carbon-sulfur waste residue, which is characterized in that it includes the following steps: (1) Modify the iron-carbon-sulfur waste residue to obtain a modified waste residue precursor; the modification design in step (1) includes iron-carbon-sulfur waste residue and modified auxiliary materials, the mass percentages of which are 70 -90:10-30, the sum of the mass percentages of the iron-carbon-sulfur waste residue and modified auxiliary materials is 100%; the modified auxiliary materials include lead tailings, sodium carbonate, barium carbonate and clarifier, which The mass ratio is 10-20:2-8:2-4:0.1-5; (2) The modified waste slag precursor obtained in step (1) is subjected to pretreatment, restricted heat treatment melting and tail gas recovery, and melt water quenching to obtain a modified base material; the restricted heat treatment temperature is 1420-1450°C; the limit The heating rate of sexual heat treatment is: 8-10℃/min in the range of 30-300℃; 3-5℃/min in the range of 300-600℃; 6-8℃/min in the range of 600-1450℃; The heat preservation time of the 300-600°C temperature zone in step (2) is 0.2-0.5h, and the heat preservation time of the 1420-1450°C temperature zone is 1-2.5h; (3) The modified base material obtained in step (2) is first subjected to sintering pretreatment to obtain a base material green body, and then the base material green body is subjected to a multi-step hierarchical heat treatment. The multi-step hierarchical heat treatment is to sinter the base material green body. For crystallization treatment, 11 step temperature heat treatment conditions are set based on the thermal analysis curve, which are 130-160℃/1-2.5h, 400-500℃/1-2.5h, 550-600℃/1-2.5h, 650 -750℃/1-2.5h, 780-810℃/1-2.5h, 850-900℃/1-2.5h, 1000-1020℃/1-2.5h, 1040-1060℃/1-2.5h, 990 -1110℃/1-2.5h, 1130-1160℃/1-2.5h, 1180-1200℃/1-2.5h; the heating rate at 30-500℃ is 5-8℃/min; at 500-750 The heating rate at ℃ temperature is 1-3℃/min; the heating rate at 750-1200℃ is 4-6℃/min. 2. The _method according to claim 1, _{characterized} in that: the lead tailings include components _SiO2 , _Al2O3 , _Fe2O3 , and the weight ratio is 55-70:8-20:3- 8; The lead tailings also include three or at least four of the components CaO, Na ₂ O, K ₂ O, MgO, ZnO, TiO ₂ and CuO, CaO, Na ₂ O, K ₂ O, MgO, The proportions of ZnO, TiO ₂ and CuO in the lead tailings are independently 0-5wt%, but not 0. 3. The method according to claim 1, characterized in that: the clarification agent _includes one or a combination of at least two of _CeO2 , _Sb2O3 , _NaSbO3 , _NaNO3 ; the _CeO2 , Sb The proportions of ₂ O ₃ , NaSbO ₃ , and NaNO ₃ in the modified waste residue precursor raw material are independently 0.1-5 wt%. 4. The method according to claim 1, characterized in that: the iron-carbon-sulfur waste residue in step (1) includes components _SiO2 , _Fe2O3 , _CaO , C, _{Al2O3 ,} ZnO, MnO , CuO, Na ₂ O, MgO and SO ₃ , the weight ratio of each component is 20-35:15-35:10-20:1-3:3-5:2-4:0.4-4:2-5 :0.6-2:0.5-2:0.9-3. 5. The method according to claim 1, characterized in that: the pretreatment in step (2) includes drying, ball milling and multi-stage screening of the modified waste residue precursor; The drying temperature in step (2) is 120-160°C; the ball milling speed is 350-450rpm; the multi-stage screening includes first removing rust impurities with a sieve set method, and then fully ball-milling the screened modified waste residue precursor. Secondary screening; screening particle size 180-200 mesh. 6. The method according to claim 1, characterized in that: the restrictive heat treatment and melting in step (2) is carried out in a box furnace; The tail gas recovery in step (2) is a CO ₂ /SO _x tail gas recovery device; The temperature of the water in the water quenching in step (2) is 15-30°C. 7. The method according to claim 1, characterized in that: the sintering pretreatment in step (3) includes filtering, drying, ball milling, and screening the modified base material; the drying temperature is 120-160°C; ball milling Rotation speed 350-450rpm; screening particle size 180-200 mesh. 8. The method according to claim 1, characterized in that: step (3) is carried out in a KSL1200 crystallization furnace; The modified base material described in step (3) is subjected to multi-stage screening before heat treatment to obtain a 180-200 mesh modified base material. 9. A series of sintered samples containing andradite-based glass-ceramics obtained by applying a method of preparing andradite-based glass-ceramics using iron-carbon-sulfur waste residue as described in any one of claims 1 to 8. 10. Application of the crystallized glass as claimed in claim 9 in the fields of construction, metallurgy, machinery or chemical industry.