WO2024109463A1 - Low-carbon underground filling material and preparation method therefor - Google Patents

Abstract

The present invention relates to the technical field of mine underground filling. Disclosed are a low-carbon underground filling material and a preparation method therefor. The underground filling material comprises the following raw material components in parts by weight: 20-100 parts of commercial cement or cementing powder, 20-100 parts of a metal smelting slag derived material, 500-5000 parts of beneficiation tailings, and a proper amount of water. According to the low-carbon underground filling material provided by the present invention, the cement consumption can be reduced by 40% or above, and the contribution to carbon emission reduction is great; a large amount of smelting slag and beneficiation tailings can be consumed; the volumetric shrinkage is reduced to 3% or below; the compressive strength of the filling material is improved by 20% or above, and the filling material achieves self-leveling and has good water retention properties (the bleeding rate being 3% or below). The filling material has extremely high application value for mine restoration and comprehensive recycling of tailings.

Description

A low-carbon underground filling material and preparation method thereof

The present invention claims the priority of the Chinese patent application filed with the Chinese Patent Office on November 21, 2022, with application number 202211454123.3, and invention name “A low-carbon downhole filling material and its preparation method”, the entire contents of which are incorporated by reference into the present invention.

Technical Field

The invention relates to the technical field of underground mine filling, and in particular to a low-carbon underground filling material and a preparation method thereof.

Background technique

Mine underground filling can not only compensate for the underground space after mining, thus ensuring the safety of subsequent mining and geological structure, but also consume some tailings to reduce the environmental protection and safety problems caused by the accumulation of tailings on the surface. Traditional underground filling materials tend to be directly mixed with ore dressing tailings slurry, cement, natural sand or machine-made sand (some areas also need to be mixed with fine gravel for filling), and then diluted with water and filled into the underground mine. This type of filling slurry requires more cement, natural or machine-made sand and gravel, resulting in a small consumption of tailings, and relies on water as a dilution and transportation medium. The filling slurry has a low concentration (35-45%), a long setting time (usually more than 3 days), a low strength (0.6-1.2MPa), and more than 40% of the water seepage seriously penetrates the surrounding mining, threatening the safety of subsequent mining.

With the promotion and application of thickeners, especially deep cone thickeners, the concentration of beneficiation tailings slurry has increased from 40% to more than 70%, which provides greater flexibility for the deployment of filling materials. Therefore, in recent years, the mainstream form of filling materials has gradually transformed into a filling paste formed by beneficiation tailings, cement and water. Compared with traditional underground filling materials, the concentration of the whole tailings filling paste is higher (usually 55-65%), the strength is adjustable (when the lime-sand ratio is between 1:4 and 8, the strength is 1.5-3.5MPa), and it can consume 20-30% of beneficiation tailings (not relying on natural or machine-made sand and gravel). However, the full-tail paste is sensitive to concentration in actual production, which usually manifests as follows: when too much water is added, it will separate and stratify, resulting in low strength of the underground filling structure, poor structural reliability, long coagulation time (more than 40 hours), and excessive water seepage (more than 20%) that needs to be pumped back to the ground; when insufficient water is added, the paste is too thick, the pumping energy consumption increases significantly, the filling pipeline wears faster, and even causes pipe blockage, underground paste accumulation and inability to flow to form the sufficient filling required by the design. Therefore, the full-tail filling currently faces production process The outstanding problems are poor operability and large fluctuations in paste quality. On the other hand, the high cost of filling paste is also caused by the large amount of cement used. The high energy consumption and high cement consumption in the production and filling process of the whole tail paste also directly lead to an increase in carbon dioxide emissions.

After the above-mentioned traditional filling slurry and full-tail filling paste enter the underground void area, they will shrink in volume during solidification due to factors such as seepage and excessive volatilization of free water. The severe shrinkage rate exceeds 10%, which also causes the filling structure to be incomplete and requires secondary support or manual plugging of prefabricated parts, increasing the construction complexity of the filling structure and the potential safety hazards of operation.

As tailings ponds gradually fill up, the demand for mine filling across the country is becoming increasingly huge, and innovative low-carbon new filling materials and technologies urgently need to be developed and applied.

Usually, there are smelting waste slag in the mine itself or in its surrounding area (the subsequent link of the mine is smelting). The present invention transforms the waste slag from the smelting of steel, copper and antimony into fine powder of derivative materials with cementing activity, with less cement and more whole tailings or fine tailings (after separating 25-35% of the coarse particles below 150 mesh in the whole tailings, the remaining fine tailings particles are called fine tailings). Under the action of the independently developed plasticizer, the present invention proposes a new mine underground filling material with low carbon dioxide emissions, good fluidity and excellent homogeneity, and a production method thereof.

Summary of the invention

In view of the defects of high energy consumption, high cost and low utilization rate of ore dressing tailings in the prior art, the present invention proposes a low-carbon underground filling material and its preparation method. By compounding ore dressing tailings (especially whole tailings and fine tailings), the modified metal smelting waste slag derivative material with cementing activity and less cement, a new underground mine filling material with reduced carbon dioxide emissions, good fluidity and excellent homogeneity is obtained, which provides a new idea and method for the safe and large-scale resource utilization of mine tailings and smelting waste slag.

The invention provides a low-carbon underground filling material, whose raw material components include, by weight: 20 to 100 parts of commercial cement or cement powder, 20 to 100 parts of metal smelting waste slag derived materials (PSSDSM), 500 to 5000 parts of ore dressing tailings, and an appropriate amount of water.

In a preferred technical solution, the phase composition of the metal smelting waste slag derived material includes: a calcium carbonate whisker content of not less than 0.5wt%, a magnesium carbonate whisker content of not less than 0.2wt%, and an aspect ratio of the whiskers of 200-15000.

The derivative material contains calcium carbonate and magnesium carbonate whiskers with an aspect ratio of 200-15000. Since calcium carbonate and magnesium carbonate are formed during the cement hydration process, the calcium carbonate and magnesium carbonate whiskers formed in the derivative material are one-dimensional linear materials, which can expose more calcium and magnesium elements and have more contact sites with cement. Therefore, they are more compatible than inorganic fillers (or calcium carbonate nanoparticles) in the prior art, and have better flexural resistance and higher elastic modulus. The whiskers provide a template for the cement hydration process, and the calcium silicate salt can extend along the template to obtain better toughness, thereby forming a high-strength, high-toughness two-dimensional structure mineral composite system rich in in-situ dispersion. Therefore, the derivative material is an active ultrafine powder with excellent hydration and cementation properties and higher hardness properties.

In a preferred technical solution, the method for preparing the metal smelting waste slag derived material comprises the following steps:

S1. Pre-crushing: crushing the metal smelting waste slag, adding silicate seed colloid containing complexing aid during the crushing process to obtain metal smelting waste slag particles with a particle size of less than 3 mm;

S2, ball milling and CO ₂ simultaneous mineralization: the metal smelting waste slag particles obtained in step S1 are introduced into a ball mill, reaction linker and magnesium salt structure regulating agent are added, and the first mixing and grinding is performed until the specific surface area is 350-550m ² /kg; CO ₂ is then introduced, and mixing and grinding is continued to obtain metal smelting waste slag derivative materials.

Preferably, the complexing aid in the silicate seed colloid containing the complexing aid is an alkyd solution, the alcohol in the alkyd solution is a polymeric polyol, and the acid in the alkyd solution is a carboxylic acid. The polymeric polyol is a liquid mixture of various organic substances such as polyols, polymeric polyols, and polymeric alcohol amines. The main components include: diethylene glycol, glycerol, dipropylene glycol, trimerol, triethanolamine (TEA), sodium fatty acid and water. Furthermore, the polymeric polyol has a molecular weight of 10,000 to 100,000 and a concentration of 1 to 10 wt%. The content of carboxylic acid in the alkyd solution is 0.5 to 5 wt%.

Preferably, the carboxylic acid includes any one of formic acid and acetic acid. Formic acid is preferred. Carboxylic acids (especially formic acid) have strong coordination ability with calcium, and the colloid is highly dispersed, which is helpful for dispersion.

Preferably, in step S1, the weight ratio of the silicate seed colloid containing the complexing aid to the metal smelting waste slag is 0.5-5%.

Preferably, in step S2, the reaction linker includes carbonate or alkali; specifically includes any one of sodium carbonate, potassium carbonate, lithium carbonate, sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium bicarbonate, potassium bicarbonate, and lithium bicarbonate.

The role of the reaction linker is to promote the formation of carbonates in the derivative material, especially the formation of calcium carbonate and magnesium carbonate.

Preferably, in step S2, the weight ratio of the reaction linker to the metal smelting waste slag particles is 0.5-3%.

Preferably, in step S2, the magnesium salt structure regulating auxiliary agent includes any one of magnesium dihydrogen phosphate, magnesium nitrate, magnesium sulfate, and magnesium acetate.

The function of the magnesium salt structure regulating additive is to regulate the growth of calcium carbonate and magnesium carbonate into one-dimensional whiskers or linear materials.

Preferably, in step S2, the weight ratio of the magnesium salt structure regulating additive to the metal smelting waste slag particles is 0.1-1%.

Preferably, the method for preparing the metal smelting waste slag derived material further comprises: adding a calcium supplement and/or a silicon supplement while adding a reaction linker and a magnesium salt structure regulating agent. Since the element content in the steel smelting waste slag fluctuates greatly, the calcium and silicon supplements are used to supplement the elements with less content therein.

Preferably, the calcium supplement is a commonly used calcium-containing substance that can react with _CO2 , such as calcium salt, calcium oxide, calcium hydroxide, etc., more preferably any one or more of desulfurized gypsum, quicklime, slaked lime, and limestone. The weight ratio of the calcium supplement to the metal smelting waste slag particles is 0.1-0.5%.

Preferably, the silicon element supplement is a commonly used silicon-containing substance, more preferably any one or more of fly ash, white carbon black, silica ash, quartz sand, and glass waste, and the weight ratio of the silicon element supplement to the metal smelting waste slag particles is 2-20%.

Preferably, in step S2, the temperature of the continued mixing and grinding is 100-300°C, the time is 5-10 min, and the grinding degree is such that the residue on the 45 μm square hole sieve is less than 20%.

Preferably, in step S2, the _CO2 can also be a gas containing _CO2 , for example, it can be smelting waste gas (after desulfurization and denitrification treatment) or water vapor containing _CO2 or other gases containing _CO2 . The process of the present invention can directly treat the smelting waste gas, and there are no strict requirements on the carbon dioxide content, other gas components, temperature, etc. in the waste gas, so as to achieve carbon emission reduction. It should be noted that, according to the description of the present invention, those skilled in the art should select pure _CO2 or gas containing _CO2 (such as smelting waste gas or water vapor containing _CO2 ), which should be within the protection scope of the present invention.

In the preferred technical solution, the raw material components also include: 5 to 20 parts of water-based state regulator and enhancer (URR). The water-based state regulator and enhancer is a water-soluble mixed type (rich in ionizable functional groups and non-ionic functional groups) surfactant, which makes the filler have excellent fluidity, water retention, encapsulation, and amide and sulfonate groups that promote strength growth.

In a preferred technical solution, the aqueous state regulator and enhancer is composed of an aqueous solution of 0.2-5% oleyl alcohol polyoxyethylene ether and 5-30% addition polymer; the addition polymer is isopentanol polyoxyethylene ether-acrylic acid-tert-butyl acrylamide sulfonic acid addition polymer.

In a preferred technical solution, the preparation method of the isopentanol polyoxyethylene ether-acrylic acid-tert-butyl acrylamide sulfonic acid addition polymer is as follows: 50-200 parts of acrylic acid, 5-50 parts of tert-butyl acrylamide sulfonic acid, 1000 parts of isopentanol polyoxyethylene ether, 5-15 parts of potassium persulfate, and 1000 parts of deionized water are used as substrates, and 100 parts of 1-5% ferrous acetate or sodium isoVC are uniformly added dropwise at 20-50° C. and within 60-120 minutes to obtain an addition polymer. The addition polymer is uniformly mixed with water and oleyl alcohol polyoxyethylene ether to prepare a water-based state regulator and enhancer URR containing 0.2-5% oleyl alcohol polyoxyethylene ether and 5-30% addition polymer.

In a better technical solution, "commercial cement" refers to ordinary commercially available cement, which may be silicate cement, ordinary silicate cement, slag silicate cement, pozzolanic silicate cement and fly ash silicate cement, etc. In this application, P.O 42.5 cement is used as an example.

In the better technical solution, "appropriate amount" is defined as: the technicians in this field, in actual application, use an appropriate amount of water to make the above raw material components condense into low-carbon downhole filling material according to the conventional technology in the field, and obtain a highly homogeneous low-carbon filling material with a solid content of 50-82%, self-leveling, and a setting time of no more than 24 hours, and its 14-day strength is adjustable between 1.5 and 9 MPa.

In a more preferred technical solution, the low-carbon downhole filling material can also be composed of the above-mentioned raw materials.

In a preferred technical solution, the beneficiation tailings can come from any one or more of gold, tungsten, copper, antimony, lead and zinc ores, specifically whole tailings or fine tailings or a mixture of the two. After separating 25-35% of the coarse particles above 150 mesh in the whole tailings, the remaining fine tailings particles are called fine tailings.

In a preferred technical solution, the metal smelting waste slag includes any one of steel smelting waste slag (stifling slag), copper ore smelting waste slag (stifling slag), antimony ore smelting waste slag (water-quenched slag, water-cooled slag), tungsten ore smelting waste slag or lead-zinc smelting waste slag.

The method for preparing the low-carbon downhole filling material provided by the present invention comprises mixing and stirring the above-mentioned raw materials evenly.

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

1. By using materials derived from metal smelting waste slag after transformation and processing, the amount of cement-based adhesives used in fillers can be reduced by more than 40%, making a huge contribution to carbon emission reduction.

2. A large amount of smelting waste slag and mineral processing tailings are consumed, especially fine tailings (usually accounting for more than 60% of the total mineral processing tailings) can be used to produce high-fluidity and high-strength filling fluids. This provides practical technical support for the comprehensive resource utilization of mine tailings and the construction of tailings-free mines, and provides a scientific solution to the "bottleneck" problem of mines that tailings cannot be fully absorbed.

3. The micro-expansion performance of the metal smelting waste slag derived materials after scientific transformation can reduce the volume shrinkage of the filling body to less than 3%;

4. The synergistic effect of metal smelting waste slag derivative materials, water-based state adjustment and enhancer URR can increase the compressive strength of the filling material by more than 20%, and the filling material can achieve self-leveling (slump/expansion can reach more than 270/700mm, and the working performance of the filling material and other mixtures can refer to GB/T50080-2016 "Standard for Performance Test Methods of Ordinary Concrete Mixtures"), and has good water retention (water seepage rate below 3%).

5. Compared with traditional filling slurries and full-tail filling pastes, the new filling material of the present invention has excellent pumping and self-flowing performances, and can fill long-distance and special-shaped mined-out structures in underground spaces with lower energy consumption and less pipeline wear.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

FIG1 is a SEM electron microscope image of the steel smelting waste slag derived material prepared in Example 2 of the present invention at different magnifications;

Among them, (a) 3000 magnification, (b) 5000 magnification, (c) 10000 magnification.

FIG2 is an XRD spectrum of each phase in the steel smelting waste slag derived material prepared in Example 2 of the present invention;

Among them, (a) CaCO ₃ , (b) MgCO ₃ , (c) Ca ₂ SiO ₄ , and (d) SiO ₂ .

Detailed ways

The technical solution of the present invention is described below through specific implementation methods, which are used to support each technical solution defined in the claims.

A low-carbon underground filling material, whose raw material components include, by weight: 20-100 parts of commercial cement or cement powder, 20-100 parts of metal smelting waste slag derived materials (PSSDSM), 500-5000 parts of ore dressing tailings, and appropriate amount of water.

In a preferred embodiment, the phase composition of the smelting waste slag derived material includes: a calcium carbonate whisker content of not less than 0.5wt%, a magnesium carbonate whisker content of not less than 0.2wt%, and an aspect ratio of the whiskers of 200-15000.

The derivative material contains calcium carbonate and magnesium carbonate whiskers with an aspect ratio of 200-15000. Since calcium carbonate and magnesium carbonate are formed during the cement hydration process, the calcium carbonate and magnesium carbonate whiskers formed in the derivative material are one-dimensional linear materials, which can expose more calcium and magnesium elements and have more contact sites with cement. Therefore, they are more compatible than inorganic fillers (or calcium carbonate nanoparticles) in the prior art, and have better flexural resistance and higher elastic modulus. The whiskers provide a template for the cement hydration process, and the calcium silicate salt can extend along the template to obtain better toughness, thereby forming a high-strength, high-toughness two-dimensional structure mineral composite system rich in in-situ dispersion. Therefore, the derivative material is an active ultrafine powder with excellent hydration and cementation properties and higher hardness properties.

In a preferred embodiment, the method for preparing the metal smelting waste slag derived material comprises the following steps:

S1. Pre-crushing: crushing the metal smelting waste slag, adding silicate seed colloid containing complexing aid during the crushing process to obtain metal smelting waste slag particles with a particle size of less than 3 mm;

S2, ball milling and CO ₂ simultaneous mineralization: the metal smelting waste slag particles obtained in step S1 are introduced into a ball mill, reaction linker and magnesium salt structure regulating agent are added, and the first mixing and grinding is performed until the specific surface area is 350-550m ² /kg; CO ₂ is then introduced, and mixing and grinding is continued to obtain metal smelting waste slag derivative materials.

The ball milling process can achieve continuous carbonate crystal formation and _CO2 mineralization fixation by using mechanical friction heat, acid-base neutralization reaction heat, and carbonation reaction heat. No additional heating energy consumption is required, and no other material consumption except smelter exhaust gas is required. It can produce a product with excellent stability, significantly improved activity, and hardness. The steel smelting waste slag is derived from resource-based environmentally friendly materials with excellent strength and toughness. In the physical and chemical process of the mechanochemistry and green closed-loop chemical chain, with the assistance of structure control additives, calcium oxide, magnesium oxide, calcium hydroxide, and magnesium hydroxide in the metal smelting waste slag particles are efficiently converted into carbonate whiskers, especially in-situ calcium carbonate whiskers, so that the ground powder of the smelting waste slag becomes a micro-nano mineral composite system rich in high-strength and high-toughness two-dimensional structure. The instability caused by the hydration volume expansion of calcium oxide and magnesium oxide components is completely eliminated; the alkyd solution containing formic acid can fully disperse and complex the calcium, magnesium and other elements from steel slag, calcium and magnesium supplements, and the calcium silicate salt seeds dispersed by ball milling are evenly distributed in the metal smelting waste slag particles. When used in cement-based building materials, it promotes the nucleation of mineral phases with the same crystal form or configuration in cement, accelerates the crystallization and growth of hydrated calcium silicate, and can reasonably regulate the early hydration rate, improve the mechanical properties of cement hydrates such as compression and flexural resistance, and thus significantly improve the later strength growth of the molded body.

Furthermore, in step S1, the weight ratio of the silicate seed colloid containing the complexing agent to the metal smelting waste slag is 0.5-5%. "Crushing process" should be broadly understood as: before crushing, after crushing, and during crushing. It should be noted that, according to the description of the present invention, those skilled in the art choose to add the silicate seed colloid containing the complexing agent before crushing, after crushing, or during crushing, which should be within the protection scope of the present invention.

Furthermore, the complexing aid in the silicate seed colloid containing the complexing aid is an alkyd solution, the alcohol is a polymeric polyol, and the acid is a carboxylic acid. The polymeric polyol is a liquid mixture of various organic substances such as polyols, polymeric polyols, and polymeric alcohol amines. The main components include: diethylene glycol, glycerol, dipropylene glycol, trimeryl glycol, triethanolamine (TEA), sodium fatty acid and water. Furthermore, the polymeric polyol has a molecular weight of 10,000 to 100,000 and a concentration of 1 to 10 wt%. The content of carboxylic acid in the alkyd solution is 0.5 to 5 wt%.

Furthermore, the carboxylic acid includes any one of formic acid and acetic acid, and is preferably formic acid. Carboxylic acids (especially formic acid) have strong coordination ability with calcium, and the colloid is highly dispersed, which is helpful for dispersion.

Further, in step S2, the reaction linker includes a carbonate or an alkali; specifically includes any one of sodium carbonate, potassium carbonate, lithium carbonate, sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium bicarbonate, potassium bicarbonate, and lithium bicarbonate; the magnesium salt structure regulating auxiliary agent includes any one of magnesium dihydrogen phosphate, magnesium nitrate, magnesium sulfate, and magnesium acetate.

The role of the reaction linker is to promote the formation of carbonates in the derivative materials, especially calcium carbonate and Formation of magnesium carbonate.

The function of the structure regulating additive is to regulate the growth of calcium carbonate and magnesium carbonate into one-dimensional whiskers or linear materials.

Furthermore, the weight ratio of the reaction linker to the metal smelting waste slag particles is 0.5-3%; the weight ratio of the magnesium salt structure regulating auxiliary agent to the metal smelting waste slag particles is 0.1-1%.

Furthermore, the method for preparing the metal smelting waste slag derived material further comprises: adding a calcium supplement and/or a silicon supplement while adding a reaction linker and a magnesium salt structure regulating agent. Since the element content in the steel smelting waste slag fluctuates greatly, the calcium and silicon supplements are used to supplement the elements with less content therein.

Furthermore, the calcium supplement is a commonly used calcium-containing substance that can react with _CO2 , such as calcium salt, calcium oxide, calcium hydroxide, etc., more preferably any one or more of desulfurized gypsum, quicklime, slaked lime, and limestone. The weight ratio of the calcium supplement to the metal smelting waste slag particles is 0.1-0.5%.

Furthermore, the silicon element supplement is a commonly used silicon-containing substance, more preferably any one or more of fly ash, white carbon black, silica ash, quartz sand, and glass waste, and the weight ratio of the silicon element supplement to the metal smelting waste slag particles is 2-20%.

Furthermore, in step S2, the temperature of the continued mixing and grinding is 100-300°C, the time is 5-10 minutes, and the grinding degree is such that the residue on the 45 μm square hole sieve is less than 20%.

Furthermore, in step S2, the _CO2 can also be a gas containing _CO2 , for example, it can be smelting waste gas (after desulfurization and denitrification treatment) or water vapor containing _CO2 or other gases containing _CO2 . The process of the present invention can directly treat the smelting waste gas, and there are no strict requirements on the carbon dioxide content, other gas components, temperature, etc. in the waste gas, so as to achieve carbon emission reduction. It should be noted that, according to the description of the present invention, those skilled in the art should select pure _CO2 or gas containing _CO2 (such as smelting waste gas or water vapor containing _CO2 ), which should be within the protection scope of the present invention.

Furthermore, in step S1, the pulverizing device is a roller press. Other pulverizing devices can also be selected as long as they can grind the smelting waste slag to 3 mm.

The modified active metal smelting waste slag derivative material is rich in calcium silicate seeds, which has the function of inducing the nucleation and growth of colloids such as dicalcium silicate and tricalcium silicate for hydration, cementation and hardening, and can reduce the amount of cement-based adhesive in the filling material and improve the early strength. The calcium alumina and calcium ferrite contained in it can promote the later The ability of long-term strength growth ensures the long-term stability and safety of the filling structure.

The micro-expansion capacity of a small amount of amorphous calcium-magnesium salt contained in the metal smelting waste slag derived materials during the hydrolysis process, synergistic with the water state regulation and air entraining function of the enhancer URR, can compensate for the volume shrinkage of the filling body caused by the loss of free water and ensure the morphological and dimensional stability of the filling body.

In a preferred embodiment, the raw material components also include: 5 to 20 parts of a water-based state regulator and enhancer (URR). The water-based state regulator and enhancer is a water-soluble mixed (rich in ionizable functional groups and non-ionic functional groups) surfactant that enables the filler to have excellent fluidity, water retention, encapsulation, and amide groups and sulfonate groups that promote strength growth.

The water-based state regulator and enhancer URR contains abundant hydrophilic groups such as alcohol hydroxyl, carboxyl, and sulfonic acid groups. Under the solvation effect of a small amount of water, it can fully electrostatically adsorb and disperse metal smelting waste slag derivatives, cement particles, and mineral processing tailings particles through carboxyl and sulfonic acid groups. The steric hindrance effect of the multi-branched structure can effectively ensure the highly uniform dispersion stability of the system (not easy to agglomerate and settle), so that the filling material exhibits good fluidity, uniformity, and strong water retention. It does not absorb excessive water molecules, and the calcium salt-enriched cross-linked network growth of the sulfonic acid group significantly improves the strength of the filling body.

In a preferred embodiment, the aqueous state regulator and enhancer is composed of an aqueous solution of 0.2-5% oleyl alcohol polyoxyethylene ether and 5-30% addition polymer; the addition polymer is prenol polyoxyethylene ether-acrylic acid-tert-butyl acrylamide sulfonic acid addition polymer.

In a preferred embodiment, the preparation method of the isopentanol polyoxyethylene ether-acrylic acid-tert-butyl acrylamide sulfonic acid addition polymer is as follows: 50-200 parts of acrylic acid, 5-50 parts of tert-butyl acrylamide sulfonic acid, 1000 parts of isopentanol polyoxyethylene ether, 5-15 parts of potassium persulfate, and 1000 parts of deionized water are used as substrates, and 100 parts of 1-5% ferrous acetate or sodium isoVC are uniformly added dropwise at 20-50° C. and within 60-120 minutes to obtain an addition polymer. The addition polymer is uniformly mixed with water and oleyl alcohol polyoxyethylene ether to prepare a water-based state regulator and enhancer URR containing 0.2-5% oleyl alcohol polyoxyethylene ether and 5-30% addition polymer.

In a preferred embodiment, "commercial cement" refers to ordinary commercially available cement, which may be silicate cement, ordinary silicate cement, slag silicate cement, pozzolanic silicate cement and fly ash silicate cement, etc. In this application, P.O 42.5 cement is used as an example.

In a preferred embodiment, "appropriate amount" is defined as: a person skilled in the art, according to conventional techniques in the art, uses an appropriate amount of water in practical applications to allow the above raw material components to condense into a low Carbon downhole filling material can be used to obtain a high-homogeneity low-carbon filling material with a solid content of 50-82%, self-leveling, and a setting time of no more than 24 hours. The 14-day strength thereof is adjustable between 1.5 and 9 MPa.

In a preferred embodiment, the low-carbon downhole filling material may also be composed of the above-mentioned raw materials.

In a preferred embodiment, the beneficiation tailings can come from any one or more of gold, tungsten, copper, antimony, lead and zinc ores, specifically whole tailings or fine tailings or a mixture of the two. After separating 25-35% of the coarse particles larger than 150 mesh in the whole tailings, the remaining fine tailings are called fine tailings.

In a preferred specific embodiment, the smelting waste slag includes any one of steel smelting waste slag (stifled slag), copper ore smelting waste slag, antimony ore smelting waste slag (water quenched slag, water-cooled slag), tungsten ore smelting waste slag (stifled slag) or lead and zinc smelting waste slag.

A method for preparing the above-mentioned low-carbon downhole filling material is to mix and stir the above-mentioned raw materials evenly.

The new underground mine filling material proposed by the present invention is produced by compounding ore dressing tailings (especially whole tailings and fine tailings) with metal smelting waste slag derivative materials and a small amount of cement-based adhesive, and has the characteristics of reducing carbon dioxide emissions, good fluidity and excellent homogeneity.

The technical scheme of the present invention is further described by examples below. It should be noted that the raw materials, reagents and equipment involved in the present invention are all common commercial products. The boiling method for stability test refers to GB/T1346-2011 "Test Method for Water Consumption, Setting Time and Stability of Cement Standard Consistency", and the working performance of mine filling materials refers to GB/T50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures".

Example 1

Preparation of copper smelting water-quenched slag derived materials:

First, a calcium silicate seed colloid is prepared: formic acid is dissolved in a polymer polyol with a concentration of 1%, and the mass content of formic acid in the alkyd solution is 5%; 40 parts of 20% sodium silicate and 20 parts of 10% calcium hydroxide suspension are simultaneously dropped into 1000 parts of the alkyd solution at 20° C. under rapid stirring to obtain a calcium silicate seed colloid CSG containing a complexing aid;

Then, 5 parts of CSG and 1000 parts of copper smelting water-quenched slag were added to a roller press, rolled into particles less than 3 mm, and then fed into a ball mill, where they were ball-milled until the residue on a 45 μm square sieve was less than 20%.

In the previous step, 5 parts of potassium carbonate and 10 parts of magnesium dihydrogen phosphate are added to every 1,000 parts of base material entering the ball mill as carbonate formation reaction linker and structure regulation auxiliary agent, 5 parts of desulfurized gypsum or 200 parts of pulverized coal. The ash is used as a calcium and silicon supplement, mixed and ground for 10 minutes, and then a mixed hot gas with a CO ₂ content of 10% and the rest water at 100°C is introduced at 1m ³ /min for 5 minutes, and ball milling is continued for 20 minutes to prepare a copper smelting water-quenched slag derivative material.

Preparation of aqueous conditioner and enhancer (URR):

The synthetic base material consists of 50 parts of acrylic acid, 5 parts of tert-butyl acrylamide sulfonic acid, 1000 parts of isopentanol polyoxyethylene ether, 5 parts of potassium persulfate and 1000 parts of deionized water. 100 parts of 1% ferrous acetate are uniformly added at 20°C within 60 minutes to obtain an addition polymer. The addition polymer is uniformly mixed with water and oleyl alcohol polyoxyethylene ether to prepare an aqueous state regulator and enhancer URR containing 0.2% oleyl alcohol polyoxyethylene ether and 5% addition polymer.

Preparation and main properties of low carbon filler:

Control group: 100 parts of P.O 42.5 cement, 800 parts of copper mine tailings (water content 35%), and 150 parts of water were evenly mixed to form a tailings filling paste. The measured slump/expansion was 220/470mm, the water seepage rate was about 12%, the setting time was about 37 hours, the volume shrinkage rate was about 8.5%, and the 7-day and 14-day strengths were 1.05 and 1.33MPa respectively.

Test group of new low-carbon filling material: 50 parts of P.O 42.5 cement, 50 parts of copper smelting water-quenched slag derivative materials, 1200 parts of copper mine tailings (water content 35%), 5 parts of URR, mixed together to form a low-carbon filling material with a solid content of 67.7%, the actual slump/expansion is 275/710mm, the water seepage rate is 0, the setting time is about 19 hours, the volume shrinkage rate is about 3.6%, and the 7-day and 14-day strengths are 1.37 and 1.85MPa respectively.

Example 2

Preparation of materials derived from water-splashed slag in steel smelting tanks:

Formic acid is dissolved in a polymer polyol having a concentration of 1%, and the mass content of formic acid in the alkyd solution is 5%. Under rapid stirring at 20° C., 5 parts of 20% sodium silicate and 1 part of 10% calcium hydroxide suspension are simultaneously dropped into 1000 parts of the alkyd solution to obtain calcium silicate seed colloid CSG containing an alkyd complexing aid;

As shown in FIG1 , 50 parts of CSG and 1000 parts of PSS (steel smelting water-splashed tank waste slag, Xiangtan Steel) were added to a roller press, and the PSS was crushed into particles less than 3 mm and entered into a ball mill, where it was ball-milled until the residue on a 45 μm square hole sieve was less than 20%;

For every 1000 parts of the base material entering the ball mill, add 5 parts of sodium carbonate, 1 part of magnesium dihydrogen phosphate, 1 part of desulfurized gypsum and 2 parts of slaked lime, mix and grind for 3 minutes, and then introduce ¹²⁰ ℃ 10% CO ₂ and 90% After mixing hot gas with water for 10 minutes, the smelter CO ₂ waste gas treated with desulfurization and denitrification is continuously circulated, and the ball milling is continued for 40 minutes to prepare the steel smelting water-splashed slag derived material (PSSDSM). Figure 1 is the SEM morphology of PSSDSM, which can be clearly seen that the whisker length is 0.1-5μm, and the aspect ratio is about 200-15000; combined with the XRD in Figure 2, it can be clearly seen that the whiskers are calcium carbonate and magnesium carbonate whiskers. As shown in Figure 2, compared with the steel slag raw material, the diffraction peak intensity of crystalline silicon oxide (SiO ₂ ), dicalcium silicate (2CaO·SiO ₂ ), calcium carbonate (CaCO ₃ ), and magnesium carbonate (MgCO ₃ ) in the modified and processed material is significantly increased, indicating that the content of the corresponding substances is also increased accordingly. The content of calcium carbonate whiskers is not less than 0.5wt%, and the content of magnesium carbonate is not less than 0.2wt%.

Preparation of aqueous conditioner and enhancer (URR):

The synthetic base material consists of 200 parts of acrylic acid, 50 parts of tert-butyl acrylamide sulfonic acid, 1000 parts of isopentanol polyoxyethylene ether, 15 parts of potassium persulfate and 1000 parts of deionized water. 100 parts of 5% sodium isoVC are uniformly added at 50°C within 120 minutes to obtain an addition polymer; the addition polymer is uniformly mixed with water and oleyl alcohol polyoxyethylene ether to prepare a water-based state regulator and enhancer URR containing 5% oleyl alcohol polyoxyethylene ether and 30% addition polymer.

Preparation and main properties of low carbon filler:

Control group: 100 parts of P.O 42.5 cement, 600 parts of gold mine tailings (water content 45%), and 230 parts of water were evenly mixed to form a tailings filling paste. The measured slump/expansion was 210/450mm, the water seepage rate was 10.5%, the setting time was about 45 hours, the volume shrinkage rate was about 10.7%, and the 7-day and 14-day strengths were 0.73 and 1.02MPa respectively.

Test group of new low-carbon filling material: 45 parts of P.O 42.5 cement, 55 parts of steel smelting water-splashed slag derivative materials, 1100 parts of gold mine tailings (water content 45%), 20 parts of URR, mixed together to become a low-carbon filling material with a solid content of 58.8%, the measured slump/expansion is 285/750mm, the water seepage rate is 2.2%, the setting time is about 23 hours, the volume shrinkage rate is about 4.3%, and the 7-day and 14-day strengths are 1.12 and 1.61MPa respectively.

Example 3

The preparation of the steel smelting water-splashed slag derivative material and the preparation of the water-based state regulator and enhancer (URR) are the same as in Example 2.

The formulation and main properties of low carbon fillers:

Control group: 100 parts of P.O 42.5 cement, 400 parts of tungsten ore fine tailings (after filter pressing, water content 18%), and 210 parts of water were evenly mixed to form a fine tailings filling paste. The measured slump/expansion was 205/420mm, the water seepage rate was 5.6%, the setting time was about 30 hours, the volume shrinkage rate was about 12.5%, and the 7-day and 14-day strengths were 2.33 and 3.12MPa respectively.

Test group of new low-carbon filling material: 40 parts of P.O 42.5 cement, 60 parts of steel smelting water-splashed slag derived materials, 800 parts of tungsten ore fine tailings (after filter pressing, water content 18%), 12 parts of URR, 60 parts of water, mixed together to form a low-carbon filling material with a solid content of 77.9%, the actual slump/expansion is 280/720mm, the water seepage rate is 0, the setting time is about 17 hours, the volume shrinkage rate is about 2.7%, and the 7-day and 14-day strengths are 3.45 and 5.16MPa respectively.

Example 4

Preparation of materials derived from antimony smelting quenching slag:

First, a calcium silicate seed colloid is prepared: formic acid is dissolved in a polymer polyol with a concentration of 8%, and the mass content of formic acid in the alkyd solution is 2%; 20 parts of 20% sodium silicate and 10 parts of 10% calcium hydroxide suspension are simultaneously dropped into 1000 parts of the alkyd solution at 40° C. under rapid stirring to obtain a calcium silicate seed colloid CSG containing a complexing aid;

Subsequently, 40 parts of CSG and 1000 parts of antimony smelting air-quenched slag are added to a roller press, rolled into particles less than 3 mm and enter a ball mill. The mass contents of φ20, φ10, φL10×15, and φL5×10 steel balls and two steel forgings in the balls and ball forgings filled in the ball mill are 15%, 18%, 15%, and 18%, respectively. In addition, 20 parts of potassium hydroxide and 5 parts of magnesium dihydrogen phosphate are added as carbonate generation reaction linking agents and structure regulation aids to every 1000 parts of base materials entering the ball mill, and 4 parts of desulfurized gypsum or 120 parts of fly ash are used as calcium and silicon element supplements. The mixture is ground for 8 minutes, and then a mixed hot gas with a _CO2 content of 50% and the rest being water and a temperature of 220°C is introduced at ^1m3 /min for 6 minutes. The grinding is continued for 30 minutes to obtain antimony smelting air-quenched slag derivative materials.

Preparation of aqueous conditioner and enhancer (URR):

The synthetic base material consists of 150 parts of acrylic acid, 40 parts of tert-butyl acrylamide sulfonic acid, 1000 parts of isopentanol polyoxyethylene ether, 10 parts of potassium persulfate and 1000 parts of deionized water. 100 parts of 3% sodium isoVC are uniformly added at 35°C within 100 minutes to obtain an addition polymer; the addition polymer is uniformly mixed with water and oleyl alcohol polyoxyethylene ether to prepare a water-based state regulator and enhancer URR containing 3.5% oleyl alcohol polyoxyethylene ether and 20% addition polymer.

Preparation and main properties of low carbon filler:

Control group: 100 parts of P.O 42.5 cement, 700 parts of antimony ore fine tailings (water content 25%), and 220 parts of water were evenly mixed to form a fine tailings filling paste. The measured slump/expansion was 185/390mm, the water seepage rate was 5.2%, the setting time was about 32 hours, the volume shrinkage rate was about 8.9%, and the 7-day and 14-day strengths were 1.45 and 1.93MPa respectively.

Low-carbon new filling material test group: 30 parts of P.O 42.5 cement, 70 parts of antimony ore smelting wind quenching slag derivative materials, 1500 parts of antimony ore fine tailings (water content 25%), 15 parts of URR, mixed together to become a low-carbon filling material with a solid content of 76.6%, the measured slump/expansion is 280/715mm, the water seepage rate is 0, the setting time is about 21 hours, the volume shrinkage rate is about 3.8%, and the 7-day and 14-day strengths are 1.97 and 2.52MPa respectively.

Example 5

Preparation of materials derived from water-quenched slag from lead-zinc ore smelting:

First, a calcium silicate seed colloid is prepared: formic acid is dissolved in a polymer polyol with a concentration of 5%, and the mass content of formic acid in the alkyd solution is 3%; 15 parts of 20% sodium silicate and 8 parts of 10% calcium hydroxide suspension are simultaneously dropped into 1000 parts of the alkyd solution at 30° C. under rapid stirring to obtain a calcium silicate seed colloid CSG containing a complexing aid;

Subsequently, 30 parts of CSG and 1000 parts of lead-zinc ore smelting water-quenched slag are added to a roller press, rolled into particles less than 3 mm and enter a ball mill. The mass contents of φ20, φ10, φL10×15, and φL5×10 steel balls and two steel forgings in the balls and ball forgings filled in the ball mill are not less than 12%, 15%, 12%, and 15%, respectively. In addition, 15 parts of sodium hydroxide and 3 parts of magnesium dihydrogen phosphate are added to every 1000 parts of base material entering the ball mill as carbonate generation reaction linking agents and structure regulation aids, and 2 parts of desulfurized gypsum or 90 parts of fly ash are used as calcium and silicon element supplements. The mixture is ground for 5 minutes, and then a mixed hot gas with a _CO2 content of 30% and the rest of water and a temperature of 150°C is introduced at ^2m3 /min for 7 minutes. The grinding is continued for 35 minutes to obtain the lead-zinc ore smelting water-quenched slag derivative material.

Preparation of aqueous conditioner and enhancer (URR):

The synthetic base material consists of 90 parts of acrylic acid, 30 parts of tert-butyl acrylamide sulfonic acid, 1000 parts of isopentanol polyoxyethylene ether, 6 parts of potassium persulfate and 1000 parts of deionized water. 100 parts of 2% ferrous acetate are uniformly added at 32°C within 80 minutes to obtain an addition polymer; the addition polymer is uniformly mixed with water and oleyl alcohol polyoxyethylene ether to prepare a water-based state regulator and enhancer URR containing 2% oleyl alcohol polyoxyethylene ether and 18% addition polymer.

The formulation and main properties of low carbon fillers:

Control group: 100 parts of P.O 42.5 cement, 400 parts of whole tailings of lead-zinc ore (water content 30%), and 180 parts of water were evenly mixed to form a whole tailings filling paste. The measured slump/expansion was 210/4300mm, the water seepage rate was 4.3%, the setting time was about 29 hours, the volume shrinkage rate was about 7.5%, and the 7-day and 14-day strengths were 2.89 and 3.57MPa respectively.

Low-carbon new filling material test group: 45 parts of P.O 42.5 cement, 55 parts of lead-zinc ore smelting water quenching derivative materials, 1000 parts of lead-zinc ore tailings (water content 30%), 12 parts of URR, mixed together to form a low-carbon filling material with a solid content of 72.7%, the measured slump/expansion is 275/730mm, the water seepage rate is 0, the setting time is about 18 hours, the volume shrinkage rate is about 2.7%, and the 7-day and 14-day strengths are 4.03 and 6.15MPa respectively.

Example 6

Preparation of materials derived from tungsten smelting slag:

Acetic acid is dissolved in a polymer polyol with a concentration of 10%, and the mass content of acetic acid in the alkyd solution is 0.5%. Under rapid stirring at 50° C., 40 parts of 20% sodium silicate and 20 parts of 10% calcium hydroxide suspension are simultaneously dropped into 1000 parts of the alkyd solution to obtain calcium silicate seed colloid CSG containing an alkyd complexing aid;

The tungsten smelting slag is rolled into particles less than 3 mm, and then 5 parts of CSG and 1000 parts of tungsten smelting slag rolled into small particles are put into a ball mill together and ball-milled until the residue on a 45 μm square hole sieve is less than 20%;

For every 1000 parts of base material entering the ball mill, add 30 parts of potassium carbonate, 10 parts of magnesium nitrate, 5 parts of de-quicklime and 2 parts of limestone, mix and grind for 10 minutes, then introduce mixed hot air containing 80% _CO2 and 20% water at 150°C at ^5m3 /min for 5 minutes, continuously circulate _CO2 waste gas from the smelter that has been treated with desulfurization and denitrification, and continue ball milling for 20 minutes to prepare tungsten smelting slag derivative materials.

The preparation of aqueous state regulator and enhancer (URR) is the same as in Example 2.

The formulation and main properties of low carbon fillers:

Control group: 100 parts of P.O 42.5 cement, 400 parts of tungsten ore fine tailings (after filter pressing, water content 18%), and 210 parts of water were evenly mixed to form a fine tailings filling paste. The measured slump/expansion was 205/420mm, the water seepage rate was 5.6%, the setting time was about 30 hours, the volume shrinkage rate was about 12.5%, and the 7-day and 14-day strengths were 2.33 and 3.12MPa respectively.

Low-carbon new filling material test group: PO 42.5 cement 40 parts, tungsten smelting slag derived materials 60 parts, 800 parts of tungsten ore fine tailings (after filtration, water content 18%), 12 parts of URR, and 60 parts of water are mixed together to form a low-carbon filling material with a solid content of 77.9%. The measured slump/expansion is 280/720mm, the water seepage rate is 0, the setting time is about 17 hours, the volume shrinkage rate is about 2.8%, and the 7-day and 14-day strengths are 3.41 and 5.14MPa respectively.

The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims (12)

1. A low-carbon underground filling material, characterized in that, in parts by weight, its raw material components include: 20 to 100 parts of commercial cement or cement powder, 20 to 100 parts of metal smelting waste slag derived materials, 500 to 5000 parts of ore dressing tailings, and an appropriate amount of water;

   The phase composition of the metal smelting waste slag derived material includes: the content of calcium carbonate whiskers is not less than 0.5wt%, the content of magnesium carbonate whiskers is not less than 0.2wt%, and the aspect ratio of the whiskers is 200-15000.
2. The low-carbon downhole filling material according to claim 1 is characterized in that the method for preparing the metal smelting waste slag derived material comprises the following steps:

   S1. Pre-crushing: crushing the metal smelting waste slag, adding silicate seed colloid containing complexing aid during the crushing process to obtain metal smelting waste slag particles with a particle size of less than 3 mm;

   S2, ball milling and CO ₂ simultaneous mineralization: the metal smelting waste slag particles obtained in step S1 are introduced into a ball mill, reaction linker and magnesium salt structure regulating agent are added, and the first mixing and grinding is performed until the specific surface area is 350-550m ² /kg; CO ₂ is then introduced, and mixing and grinding is continued to obtain metal smelting waste slag derivative materials.
3. The low-carbon downhole filling material according to claim 2, characterized in that, in step S1, the complexing aid in the silicate seed colloid containing the complexing aid is an alkyd solution, the alcohol in the alkyd solution is a polymeric polyol, and the acid in the alkyd solution is a carboxylic acid; and/or,

   The weight ratio of the silicate seed colloid containing the complexing aid to the metal smelting waste slag is 0.5-5%.
4. The low-carbon downhole filling material according to claim 2, characterized in that the reaction linker comprises carbonate or alkali; and/or,

   The weight ratio of the reaction linking agent to the metal smelting waste slag particles is 0.5-3%.
5. A low-carbon downhole filling material according to claim 2, characterized in that the magnesium salt structure regulating auxiliary agent includes any one of magnesium dihydrogen phosphate, magnesium nitrate, magnesium sulfate, and magnesium acetate; and/or,

   The weight ratio of the magnesium salt structure regulating auxiliary agent to the metal smelting waste slag particles is 0.1-1%.
6. The low-carbon downhole filling material according to claim 2 is characterized in that, in step S2, the temperature of the continued mixing and grinding is 100-300° C. and the time is 5-10 minutes.
7. A low-carbon underground filling material according to any one of claims 1 to 6, characterized in that the metal smelting waste slag includes any one of steel smelting slag, tungsten ore smelting slag, lead and zinc smelting waste slag, copper ore smelting waste slag or antimony ore smelting waste slag.
8. A low-carbon downhole filling material according to any one of claims 1 to 6, characterized in that The invention comprises 5 to 20 parts of a water-based state regulator and enhancer; the water-based state regulator and enhancer is composed of 0.2 to 5% of oleyl alcohol polyoxyethylene ether and 5 to 30% of an aqueous solution of an addition polymer; the addition polymer is an isopentanol polyoxyethylene ether-acrylic acid-tert-butyl acrylamide sulfonic acid addition polymer.
9. A low-carbon downhole filling material according to claim 8, characterized in that the preparation method of the addition polymer is as follows: using 50 to 200 parts of acrylic acid, 5 to 50 parts of tert-butyl acrylamide sulfonic acid and 1000 parts of isopentanol polyoxyethylene ether, 5 to 15 parts of potassium persulfate, and 1000 parts of deionized water as substrates, uniformly adding 100 parts of 1 to 5% ferrous acetate or sodium isoVC at 20 to 50° C. for 60 to 120 minutes to obtain an addition polymer.
10. A low-carbon underground filling material according to any one of claims 1 to 6, characterized in that the ore dressing tailings come from any one or more of gold ore, tungsten ore, copper ore, antimony ore, lead-zinc ore.
11. A low-carbon underground filling material according to any one of claims 1 to 6, characterized in that the ore dressing tailings are whole tailings or fine tailings or a mixture of the two.
12. The method for preparing a low-carbon downhole filling material as described in any one of claims 1-11 is characterized in that the raw materials are stirred and mixed evenly.