Solid waste-based cementitious material produced by using pretreated pyrite tailings and preparation method thereof

Abstract

The invention discloses a solid waste-based cementitious material, which comprises the following raw materials based on 100% of the total mass percentage: 10% to 35% of pretreated pyrite tailing powder, 30% to 50% of granulated blast furnace slag powder, 15% to 30% of steel slag powder, and the remainder being gypsum powder. The invention heats the pyrite tailing at 300°C and ultrafinely grinds the pyrite tailing to cause an oxidation reaction of pyrite and pyrrhotite contained therein to generate sulfate minerals, thereby reducing the proportion of sulfide compounds in the tailing and reducing the risk of expansion and cracking of a hardened body of the solid waste-based cementitious material in the later stage. Moreover, the sulfate generated by oxidation and the gypsum contained in the pyrite tailing react with the steel slag and slag in the solid waste-based cementitious material to generate hydrated calcium silicate gel and calcium sulfonite, thereby improving the strength of the solid waste-based cementitious material.

Description

Technical field:

[0001] The invention relates to a solid waste-based gelling material produced by utilizing pretreated pyrite tailings and a preparation method thereof. Background technology:

[0002] Pyrite tailings are solid waste discharged from pyrite mines after grinding, classification, flotation and other mineral processing processes. Large amounts of storage in tailings ponds occupy land resources and affect the surrounding ecological environment. 1～x Sulfide compounds such as ferrous sulfide (S) and the like, when exposed to the atmosphere, will produce sulfuric acid under the combined action of oxygen, water and microorganisms, forming acid mine wastewater, which will increase the solubility and activity of heavy metals, and lead to the dissolution of heavy metal solid solutions such as Cd, Hg and Pb and the release of heavy metal ions, continuously polluting the ecological environment.

[0003] At present, the resource utilization rate of pyrite tailings is low. Some scholars have studied the recovery of valuable components. After the recovery of valuable components, the large amount of pyrite and other priceless components in the tailings still face the problem of being difficult to deal with. Its comprehensive utilization still needs to find other directions. Among them, the utilization of building materials has received extensive attention from most scientific and technical personnel. At present, there are two main constraints on the utilization of pyrite tailings as building materials: first, pyrite, pyrrhotite and other minerals contained in pyrite tailings will slowly oxidize in concrete, and the secondary minerals produced will cause the matrix to expand, making the concrete have potential stability risks; second, pyrite tailings contain cement retarding components such as gypsum, and excessive addition will have an adverse effect on the coagulation, hardening and strength of cement. At present, using pyrite tailings as cement admixtures or setting regulators is a common way of utilization, but the utilization rate is low, and the proportion in cement generally does not exceed 10%.

[0004] Solid waste-based cementitious materials are a kind of hydraulic cementitious materials prepared by compositely using industrial solid wastes such as steel slag, industrial by-product gypsum, granulated blast furnace slag, etc. as raw materials. It exerts the synergistic effect between the raw materials to form cement-like cementitious properties. Gypsum, as an important component of solid waste-based cementitious materials, can accelerate the formation of hydration products such as CSH gel and AFt, and is the main source of strength of solid waste-based cementitious materials. CN116986876A discloses a road base material using pyrite tailings and a preparation method thereof, and discloses that the road base material includes: 10 to 40 parts by weight of a new type of unburned low-carbon cementitious material curing agent, 60 to 90 parts by weight of a stabilized material, and water; the components and mass percentages of the new type of unburned low-carbon cementitious material curing agent include: 15% to 40% of steel slag powder, 40% to 70% of slag powder, 5% to 30% of by-product gypsum and a special activator, and the components of the special activator include sodium carbonate, sodium sulfate and / or sodium stearate; the stabilized material is pyrite tailings. The above technology still has the problem of too high sulfide content, and the road base material is prone to expansion and cracking in the later stage. In addition, the use of activators leads to excessively high costs. Summary of the invention:

[0005] The object of the present invention is to provide a solid waste-based gelling material produced by utilizing pretreated pyrite tailings and a preparation method thereof.

[0006] The present invention is achieved through the following technical solutions:

[0007] A solid waste-based cementitious material, whose raw material composition is as follows, based on the total mass percentage of 100%, is as follows: 10% to 35% of pretreated pyrite tailings powder, 30% to 50% of granulated blast furnace slag powder, 15% to 30% of steel slag powder, and the rest is gypsum powder; the pretreated pyrite tailings powder is obtained by pretreating the pyrite tailings as follows: heating and drying the pyrite tailings at 200°C to 400°C for a heating time of not less than 30 minutes; grinding the heated and dried pyrite tailings in a mill to a specific surface area of ​​≥500m 2 / kg for later use.

[0008] Preferably, based on the total mass percentage of 100%, the raw material composition is as follows: 15% to 30% pretreated pyrite tailings powder, 40% to 50% granulated blast furnace slag powder, 15% to 20% steel slag powder, and the rest is gypsum powder.

[0009] More preferably, based on the total mass percentage of 100%, the raw material composition is as follows: 15% to 20% pretreated pyrite tailings powder, 40% to 50% granulated blast furnace slag powder, 15% to 20% steel slag powder, and the rest is gypsum powder.

[0010] The granulated blast furnace slag powder is formed by water quenching the slag discharged from blast furnace ironmaking, and the granulated blast furnace slag is ground to a specific surface area of ​​≥450m 2 / kg to obtain granulated blast furnace slag powder. .

[0011] The steel slag powder used in the present invention is the steel slag discharged from steelmaking, which is crushed, magnetically separated and ground to obtain a specific surface area of ​​≥400m 2 / kg of steel slag powder.

[0012] The gypsum powder used in the present invention is a byproduct discharged from industrial production with calcium sulfate as the main component, which is dried and ground to a specific surface area of ​​≥400m 2 / kg.

[0013] The preparation method of the solid waste-based cementitious material comprises the following steps: mixing pretreated pyrite tailing powder, granulated blast furnace slag powder, steel slag powder and gypsum powder evenly through physical and mechanical action to obtain the solid waste-based cementitious material; or grinding granulated blast furnace slag, steel slag and gypsum together to a specific surface area of ​​450 to 550 m 2 / kg, and then mixed evenly with the pretreated pyrite tailings powder to obtain a solid waste-based cementitious material.

[0014] The beneficial effects of the present invention are as follows:

[0015] By heating the pyrite tailings at 300°C and ultra-fine grinding them, the pyrite and pyrrhotite contained in them undergo oxidation reaction to generate sulfate minerals, thereby reducing the proportion of sulfide-iron compounds in the tailings and reducing the risk of expansion and cracking of the hardened solid waste-based cementitious material in the later stage; and the sulfate produced by oxidation and the gypsum contained in the pyrite tailings undergo hydration reaction with the steel slag and slag in the solid waste-based cementitious material to generate calcium silicate hydrate (CSH) gel and ettringite (AFt) (see Figure 1 ), which improves the strength of solid waste-based cementitious materials, with 3d compressive strength ≥18.5MPa, 28d compressive strength ≥45.5MPa, and 56d compressive strength ≥51.2MPa. Description of the drawings:

[0016] Figure 1 This is an electron microscope photograph of the hydration product of the pyrite tailings solid waste-based cementitious material obtained in Example 2. Specific implementation method:

[0017] The following is a further description of the present invention, rather than a limitation of the present invention.

[0018] Embodiment 1:

[0019] The pyrite tailings (from Guangdong Guangye Yunliu Mining Co., Ltd.) were heated and dried at 300°C for 30 minutes; the heated and dried pyrite tailings were ground in a mill to a specific surface area of ​​510 m 2 / kg, and the pretreated pyrite tailings powder was obtained.

[0020] Granulated blast furnace slag (from Guangxi Guigang Iron and Steel Company) was ground to a specific surface area of ​​450m 2 / kg, and obtain granulated blast furnace slag powder.

[0021] The converter slag (from Guangxi Guigang Iron and Steel Company) was crushed, magnetically separated and ground to obtain a specific surface area of ​​400m 2 / kg of steel slag powder.

[0022] The desulfurization gypsum of the power plant (China Huadian Group Guigang Power Generation Co., Ltd.) was dried and ground to a specific surface area of ​​420m 2 / kg, and obtain desulfurized gypsum powder.

[0023] According to weight percentage, 30% of pretreated pyrite tailings powder, 40% of granulated blast furnace slag powder, 20% of steel slag powder and 10% of desulfurized gypsum powder are weighed and evenly mixed in a mixer to obtain pyrite tailings solid waste-based cementitious material.

[0024] According to the relevant provisions of GB / T 28294-2024 "Steel Slag Composite Materials", the standard consistency water consumption, setting time, stability and mortar strength of pyrite tailings solid waste-based cementitious materials are tested.

[0025] Comparative Example 1:

[0026] Reference Example 1, except that the pyrite tailings were not pre-treated by heating, and the pyrite tailings (from Guangdong Guangye Yunsulphur Mining Co., Ltd.) were ground in a mill to a specific surface area of ​​510 m 2 / kg, and obtain pyrite tailings powder.

[0027] According to weight percentage, 30% of pyrite tailings powder, 40% of granulated blast furnace slag powder, 20% of steel slag powder and 10% of desulfurized gypsum powder are weighed and evenly mixed in a mixer to obtain pyrite tailings solid waste-based cementitious material.

[0028] According to the relevant provisions of GB / T 28294-2024 "Steel Slag Composite Materials", the standard consistency water consumption, setting time, stability and mortar strength of pyrite tailings solid waste-based cementitious materials are tested.

[0029] Embodiment 2:

[0030] Refer to Example 1, the difference is that the raw material ratio of the solid waste-based cementitious material is different.

[0031] According to weight percentage, 20% of pretreated pyrite tailings powder, 50% of granulated blast furnace slag powder, 20% of steel slag powder and 10% of desulfurized gypsum powder are weighed and evenly mixed in a mixer to obtain pyrite tailings solid waste-based cementitious material.

[0032] According to the relevant provisions of GB / T 28294-2024 "Steel Slag Composite Materials", the standard consistency water consumption, setting time, stability and mortar strength of pyrite tailings solid waste-based cementitious materials are tested.

[0033] Embodiment 3:

[0034] Referring to Example 1, the difference is that the raw material ratio of the solid waste-based cementitious material is different: by weight percentage, 35% of pretreated pyrite tailings powder, 35% of granulated blast furnace slag powder, 20% of steel slag powder, and 10% of desulfurized gypsum powder are weighed and evenly mixed in a mixer to obtain pyrite tailings solid waste-based cementitious material.

[0035] According to the relevant provisions of GB / T 28294-2024 "Steel Slag Composite Materials", the standard consistency water consumption, setting time, stability and mortar strength of pyrite tailings solid waste-based cementitious materials are tested.

[0036] Embodiment 4:

[0037] Referring to Example 1, the difference is that the pretreatment of the pyrite tailings powder is different, the ratio of the raw materials of the solid waste-based cementitious material is different, and the preparation method is also different.

[0038] The pyrite tailings powder pretreatment is to heat and dry the pyrite tailings at 200℃ for 60 minutes; grind the heated and dried pyrite tailings in a mill to a specific surface area of ​​550m 2 / kg, and obtain pretreated pyrite tailings powder.

[0039] The raw material ratio of solid waste-based cementitious materials is as follows: by weight percentage, 15% of pretreated pyrite tailings powder, 50% of granulated blast furnace slag powder, 15% of steel slag powder, and 20% of desulfurized gypsum powder.

[0040] The preparation method of solid waste-based cementitious material is as follows: granulated blast furnace slag, crushed and magnetically separated steel slag, and desulfurized gypsum are ground together in a weight ratio of 50:15:20 to a specific surface area of ​​500m 2 / kg to obtain a mixed powder; then mix it evenly with the pretreated pyrite tailings powder to obtain a solid waste-based cementitious material. The standard consistency water consumption, setting time, stability and mortar strength of the pyrite tailings solid waste-based cementitious material are tested in accordance with the relevant provisions of GB / T 28294-2024 "Steel Slag Composites".

[0041] Embodiment 5:

[0042] Referring to Example 1, the difference is that the pretreatment of the pyrite tailings powder is different, the ratio of the raw materials of the solid waste-based cementitious material is different, and the preparation method is also different.

[0043] The pretreatment of pyrite tailings powder is as follows: the pyrite tailings are heated and dried at 400°C for 30 minutes; the heated and dried pyrite tailings are ground in a mill to a specific surface area of ​​500m 2 / kg, and obtain pretreated pyrite tailings powder.

[0044] The raw material ratio of solid waste-based cementitious materials is: by weight percentage, 10% of pretreated pyrite tailings powder, 35% of granulated blast furnace slag powder, 30% of steel slag powder, and 25% of desulfurized gypsum powder.

[0045] The preparation method of solid waste-based cementitious material is as follows: granulated blast furnace slag, crushed and magnetically separated steel slag, and desulfurized gypsum are ground together in a weight ratio of 35:30:25 to a specific surface area of ​​550m 2 / kg to obtain a mixed powder; and then mix it evenly with the pretreated pyrite tailings powder to obtain a solid waste-based cementitious material.

[0046] According to the relevant provisions of GB / T 28294-2024 "Steel Slag Composite Materials", the standard consistency water consumption, setting time, stability and mortar strength of pyrite tailings solid waste-based cementitious materials are tested.

[0047] The test results of the above examples 1-5 are shown in the following table:

[0048]

[0049]

[0050] The test results of various performance indicators of Examples 1-5 meet the requirements of 42.5 strength grade steel slag composite cementitious materials in GB / T 28294-2024 "Steel Slag Composite Materials", and the autoclave stability of Comparative Example 1 is unqualified.

Claims

1. A solid waste-based cementitious material, characterized in that: The raw material composition is as follows, based on the total mass percentage of 100%, including 10% to 35% of pretreated pyrite tailing powder, 30% to 50% of granulated blast furnace slag powder, 15% to 30% of steel slag powder, and the remainder is gypsum powder; the pretreated pyrite tailing powder is obtained by pre-treating the pyrite tailings as follows: heating and drying the pyrite tailings at 200° C. to 400° C. for no less than 30 minutes; The heated and dried pyrite tailings are ground in a mill to a specific surface area of ​​≥500m 2 / kg for later use.

2. The solid waste-based cementitious material according to claim 1, characterized in that: Based on the total mass percentage of 100%, the raw material composition is as follows: 15% to 30% of pretreated pyrite tailings powder, 40% to 50% of granulated blast furnace slag powder, 15% to 20% of steel slag powder, and the rest is gypsum powder.

3. The solid waste-based cementitious material according to claim 1, characterized in that: Based on the total mass percentage of 100%, the raw material composition is as follows: 15% to 20% of pretreated pyrite tailings powder, 40% to 50% of granulated blast furnace slag powder, 15% to 20% of steel slag powder, and the rest is gypsum powder.

4. The solid waste-based cementitious material according to claim 1, characterized in that: The specific surface area of ​​the granulated blast furnace slag powder is ≥450m 2 / kg.

5. The solid waste-based cementitious material according to claim 1, characterized in that: Specific surface area of ​​steel slag powder ≥400m 2 / kg.

6. The solid waste-based cementitious material according to claim 1, characterized in that: Gypsum powder is a byproduct of industrial production with calcium sulfate as the main component. It is dried and ground to a specific surface area of ​​≥400m 2 / kg.

7. The method for preparing solid waste-based gelling material according to claim 1, characterized in that: The method comprises the following steps: mixing pre-treated pyrite tailing powder, granulated blast furnace slag powder, steel slag powder and gypsum powder evenly through physical and mechanical action to obtain a solid waste-based cementitious material; or grinding granulated blast furnace slag, steel slag and gypsum together to a specific surface area of ​​450 to 550 m 2 / kg, and then mixed evenly with the pretreated pyrite tailings powder to obtain a solid waste-based cementitious material.

Images