CN102492405B - Grouting material for reinforcing fragmentized coal body - Google Patents

Abstract

A grouting material for the reinforcement of broken coal bodies, consisting of two solutions A and B, A: polysilicon solution, made of E ₀ grade environmentally friendly urea-formaldehyde resin with a molar ratio of less than 1.5 and a free formaldehyde content of ≤3mg/100g and quality The concentration is 30-40% silica sol, the pH value of silica sol is 8-9, the average particle size is 7-24nm, the specific surface area is 140-400m ² /g, the viscosity is 17-20cp; the temperature is 20-30 degrees Celsius according to the mass ratio of 2:1 Milky white polysilicon solution with a mass concentration of 30-45% is mixed under the conditions, and then 4% of a special toughening agent is added to the polysilicon solution; B solution: GaCl ₂ aqueous solution with a mass concentration of 4%-10% and a mass concentration of 5% %~12% aqueous solution of oxidized starch is mixed at 1:1 at room temperature as a curing agent; A and B liquids can be quickly solidified and form strength within a few minutes to 2 hours after mixing in a mass ratio of 4:1 to 5:1 ; The grouting material is not charged, does not burn, has low viscosity, high temperature resistance, long shelf life, and can be quickly solidified and formed under the action of curing agent and toughening agent. After curing, it has high strength, does not burn, and is safe and reliable.

Description

A grouting material for reinforcement of broken coal body

technical field

The invention relates to a grouting reinforcement material for broken coal and rock bodies with relatively low strength, in particular to a grouting material for reinforcement of broken coal bodies.

Background technique

Fractured coal and rock is an engineering problem often encountered in face mining and roadway excavation. Broken roof coal seams account for a large proportion in my country. According to the survey of 38 major mining bureaus, coal seam reserves belonging to broken roof (equivalent to Type 1 roof in the roof classification) account for 54.5% of these bureaus. Therefore, roof fall accidents are very likely to occur in the mining face. During the mining and excavation of coal-rock roadways, there are generally the following safety problems: ① In the section where the coal-rock mass is severely broken, the top coal and part of the roadway directly fall on the entire width of the roadway, the depth of the side is large, and the construction is difficult. Poor safety conditions can easily cause accidents; ②The top of the roadway collapses and forms a cavity, accumulating a large amount of gas, which brings many difficulties to ventilation and gas management, and there are hidden dangers of accidents; The wooden cribs under construction are poorly connected to the top or not connected to the top, and the bracket is in an unstable state due to the empty support of the top beam. When the roof falls head-on, it is easy to cause the bracket to be smashed or collapsed.

To effectively deal with broken coal and rock, one of the usual treatment methods is to increase support materials, and the other is to inject grout. Adding supporting materials has a great impact on the movement of the coal mining support, but it cannot fundamentally solve the roof fall problem; the cement slurry cannot achieve the effect of grouting reinforcement due to its poor injectability and other engineering properties. Therefore, finding new grouting to strengthen coal rock has important research significance.

At present, chemical grouting materials (such as two-component polyurethane resin grouting materials) used for the reinforcement of broken coal bodies have the following three problems during use:

1) With high viscosity and poor fluidity, it is only suitable for local short-distance (<5m) injection grouting on the broken coal working face, and is not suitable for long borehole grouting in the air return lane and the air inlet lane. For the overall grouting of large working faces, the reinforcement effect is greatly limited;

2) The price is expensive. The current market price is between 30,000 and 40,000 per ton. It is not suitable for the application of broken coal reinforcement projects with a large amount of grouting on the working face.

3) Special imported grouting equipment is required.

4) Other types of grouting materials are potentially flammable and explosive.

Contents of the invention

The object of the present invention is to provide a low-cost, environmentally friendly, high-strength and safe grouting material for strengthening broken coal bodies in coal mines.

The purpose of the present invention is achieved in this way: the grouting material is composed of two solutions, A solution and B solution; wherein A solution is a polysilicon solution, including: urea-formaldehyde resin and silica sol, which are mixed in a mass ratio of 2:1. Mix at 20-30 degrees Celsius to form a milky white polysilicon solution with a mass concentration of 30-45%, and then add 4% of a special toughening agent to the polysilicon solution as the main liquid of the grouting material; the solid content of the urea-formaldehyde resin 35-40%, molar ratio less than 1.5, free formaldehyde content ≤ 3mg/100g E grade ₀ environment-friendly urea-formaldehyde resin; the mass concentration of the silica sol is 30-40%, the pH value of the silica sol is 8-9, and the average particle size Diameter 7~24nm, specific surface area 140~400m ² /g, viscosity 17~20cp;

B solution is solidifying agent, comprises calcium chloride and oxidized starch, and wherein the purity of calcium chloride is 90%, adds pure water in calcium chloride and oxidized starch respectively and mixes to make aqueous solution, and the mass concentration of calcium chloride aqueous solution is 4 %~10%; the mass concentration of the aqueous solution of oxidized starch is 5%~12%, according to the mass ratio of 1:1, mixed at room temperature;

The mass ratio of A solution and B solution is 4:1-5:1.

Beneficial effects, due to the adoption of the above scheme, the urea-formaldehyde resin colloid is a highly dispersed dispersion system, and its dispersed particle size is 0.1 ~10 between. Since the particles of the colloid have a large specific surface area and the free energy of the system is also high, the particles tend to automatically aggregate to reduce the surface energy of the system, which is a thermodynamically unstable system, and its stability depends on the attraction between the particles. force and repulsion. Particle collision has two results, one is that the repulsive force is greater than the attractive force, and the sol remains in its original state, and the other is that the attractive force is greater than the repulsive force, causing coalescence, so when the particle concentration is very low and cannot reach a certain surface area and surface energy, no Coalescence will occur automatically. In a sol containing no electrolyte or a very low electrolyte concentration, the repulsive force between the sol particles is sufficient to prevent the automatic aggregation between the particles, thereby maintaining the original state. On the contrary, if the above two concentrations reach a certain match, agglomeration or coagulation will occur.

In urea-formaldehyde resin, there is a double adsorption layer of protonated formaldehyde, which acts as a stabilizer during the storage period of the resin. Due to the protective film effect of the double adsorption layer of protonated formaldehyde, the effective collision chance of colloidal particle aggregation is greatly reduced, so it has a longer storage period. However, once the electrolyte is involved, the curing process will be accelerated. Taking the salt of strong acid and weak base as an example, the electrolyte dissolves, and positive and negative ions enter the glue solution, so that the pH of the glue solution first drops, then rises, and then drops again. The reason is that the action of strong acid radical ions makes the pH drop, but the acid radical immediately reacts with the outer layer of the double adsorption layer, and the result of the action makes the pH value rise, and at the same time, the exposed inner proton layer interacts with the OH- in the glue, causing the entire double adsorption layer to The adsorption layer is destroyed, the effective collision between the rubber materials is greatly improved, coalescence occurs, formaldehyde is released, H+ remains in the glue solution, and the pH drops again. From the perspective of storage, urea-formaldehyde resin glue is placed under weakly alkaline conditions, which can protect the stability of the double adsorption layer and thus have a certain storage period.

The ph value of silica sol is between 8~12, the specific surface area is 50~400m ² /g, and the particle size range is between 1-100nm, which is different from the general particle size of 0.1~10nm. The particle size of the emulsion is much smaller than that of the urea-formaldehyde resin. Therefore, the addition of silica sol has three effects on the urea-formaldehyde resin. ① It can maintain a better weak alkaline environment for the urea-formaldehyde resin solution and increase its shelf life. ② Silica sol particles are easier to disperse into the resin, further improving the mechanical properties of the mixed solution after consolidation. ③The curing of silica sol and urea-formaldehyde resin belongs to the coalescence and sedimentation process of microscopic particles. Therefore, under the action of curing agent calcium chloride and other solutions, the weak alkali environment in which urea-formaldehyde resin and silica sol coexist stably is changed, respectively, making urea-formaldehyde resin and silicon The sols coalesce and settle to form their respective three-dimensional network structures, which are interlaced with each other, and finally gel and solidify.

When strengthening the broken coal body of coal mine, the price is low, environmental protection, high strength and safety, and the purpose of the present invention has been achieved.

Advantages: The price of the new coal-fixing grouting material of the present invention is 6,000 to 9,000/ton, and its initial viscosity is as small as 20cp, with good permeability and high consolidation strength, no charge, no combustion, and high viscosity Low temperature, high temperature resistance, long shelf life, no burning, no pollution to the environment, safe and reliable, can be rapidly solidified and formed under the action of curing agent and toughening agent, the gel time can be adjusted at any time according to the construction situation on site, the adjustment range is wide, and domestic common The grouting pump is used for grouting, which is simple and convenient to use. It can be applied to the grouting reinforcement of broken coal bodies in isolated island working faces, broken coal bodies in fault zones and other broken coal bodies encountered in the underground coal mining field of coal mines.

Detailed ways

Example 1: The grouting material is composed of two solutions, A solution and B solution; wherein A solution is a polysilicon solution, including: urea-formaldehyde resin and silica sol, mixed in a mass ratio of 2:1, at a temperature of 20 to 30 degrees Celsius Mixed under conditions to generate a milky white polysilicon solution with a mass concentration of 30-45%, as the main liquid of the grouting material; the solid content of the urea-formaldehyde resin is 35-40%, the molar ratio is less than 1.5, and the free formaldehyde content is ≤3mg/ 100g of E ₀ grade environmental protection urea-formaldehyde resin; the mass concentration of the silica sol is 30-40%, the pH value of the silica sol is 8-9, the average particle size is 7-24nm, the specific surface area is 140-400m ² /g, and the viscosity is 17- 20cp;

B solution is solidifying agent, comprises calcium chloride and oxidized starch, and wherein the purity of calcium chloride is 90%, adds pure water in calcium chloride and oxidized starch respectively and mixes to make aqueous solution, and the mass concentration of calcium chloride aqueous solution is 4 %~10%; the mass concentration of the aqueous solution of oxidized starch is 5%~12%, according to the mass ratio of 1:1, mixed at room temperature;

The mass ratio of solution A to solution B is 4:1~5:1; after mixing, it can solidify rapidly and form strength within a few minutes to 2 hours.

Take 4000Kg of urea-formaldehyde resin with a solid content of 35%, E0 grade, and 4000 Kg of silica sol with a mass concentration of 35%, put it in a reaction kettle, heat it to 30 degrees, and react for 10 minutes to form a polysilicon solution. as liquid A;

The mass ratio is: 5:10:85, and 100 Kg of an aqueous solution prepared by mixing GaCl ₂ with a purity higher than 90%, oxidized starch, and purified water is used as liquid B;

Using domestic ordinary chemical grouting pumps, the A/B solution is poured into coal and rock mass under pressure conditions according to the volume ratio A:B=4:1, and wait for it to solidify.

1) Urea-formaldehyde resin is used as the grouting material. Practice has proved that when the molar ratio of urea-formaldehyde resin is less than 1.5, the slurry is difficult to solidify and gel. The polysilicon solution of the present invention is composed of E grade ₀ environment-friendly urea-formaldehyde resin with a molar ratio of less than 1.5 and a formaldehyde content of ≤3mg/100g. The solid content of the urea-formaldehyde resin is 35-40%, and the mass concentration is 30-40% silica sol, and the pH value of the silica sol is 8. ～12, average particle size 7～20nm, specific surface area 140～400m ² /g, viscosity 17～20cp, mass concentration of 30～45% by mass ratio 5:1 at 30～40℃ temperature condition Milky white polysilicon solution, fine particles of silica sol, can effectively penetrate into the active groups (-CH2OH, -NH-, -CH2-O-CH2-) of urea-formaldehyde resin, and form stable three-dimensional The network structure and the silica sol gel form a network structure interlaced with each other. It can be used as the main material for the reinforcement of broken coal bodies.

2) Practice has proved that urea-formaldehyde resins with a molar ratio of less than 1.5 are not suitable for grouting materials because they are not easy to gel and solidify, but urea-formaldehyde resins with a molar ratio of less than 1.5 are mostly environmentally friendly resins, so this grouting material is added with silica sol and calcium chloride After curing agent, the environment-friendly urea-formaldehyde resin can be applied.

2) Curing agent: an aqueous solution made by mixing calcium chloride with a purity higher than 90%, oxidized starch, and purified water. Its mass ratio is: (4~10): (5~12): (91~78).

3) The maximum compressive strength of the grouting material after consolidation can reach more than 14MPa, and the dry bonding strength can reach more than 3MPa.

4) The slurry has high strength after solidification during use, does not burn, is not charged, does not pollute the environment, is safe and reliable, and can be applied to the broken coal body of the isolated island working face, the broken coal body of the fault zone, Grouting reinforcement of broken coal bodies with relatively low strength.

Example 2: Take 4000 Kg of urea-formaldehyde resin with a solid content of 39%, E0 grade, and a mass concentration of 40% silica sol 1000 Kg, place it in a reaction kettle, heat it to 25 degrees, and react for 10 minutes to generate a polysilicon solution. as liquid A;

The mass ratio is: 10:12:78, 100 Kg of an aqueous solution made by mixing GaCl ₂ with a purity higher than 90%, oxidized starch, and purified water is used as liquid B; using a domestic ordinary chemical grouting pump, the A/B solution is The volume ratio A:B=5:1, under pressure, pour into coal and rock mass, and wait for it to solidify.

Example 3: Take 4000 Kg of urea-formaldehyde resin with a solid content of 30%, E0 grade, and a mass concentration of 37% silica sol 1000 Kg, place it in a reaction kettle, heat it to 20 degrees, and react for 10 minutes to generate a polysilicon solution. as liquid A;

The mass ratio is: 6:8:84, 100 Kg of an aqueous solution made by mixing GaCl ₂ with a purity higher than 95%, oxidized starch, and purified water is used as liquid B; using a domestic ordinary chemical grouting pump, the A/B solution is The volume ratio A:B=5:1, under pressure, pour into coal and rock mass, and wait for it to solidify.

Using domestic ordinary chemical grouting pumps, the A/B solution is poured into coal and rock mass under pressure conditions according to the volume ratio A:B=5:1, and it is enough to wait for it to solidify.

Claims (1)

1. A grouting material for strengthening broken coal bodies, characterized in that: the grouting material is composed of two solutions, A solution and B solution; wherein A solution is a polysilicon solution, including: urea-formaldehyde resin and silica sol , according to the mass ratio of 2:1, mix at 20-30 degrees Celsius to form a milky white polysilicon solution with a mass concentration of 30-45%, and then add 4% of a special toughening agent for the polysilicon solution, the toughening agent is o-phthalic acid Diformic acid ester (DOP), cresyl diphenyl phosphate (CDP) mass ratio is 1.2:0.8 room temperature liquid mixture, used as the main liquid of grouting material; the solid content of the urea-formaldehyde resin is 35-40%, the molar ratio Less than 1.5:1, E ₀ grade environmental protection urea-formaldehyde resin with free formaldehyde content ≤ 3mg/100g; the mass concentration of the silica sol is 30-40%, the pH value of the silica sol is 8-9, the average particle size is 7-24nm, the ratio Surface area 140～400m ² /g, viscosity 17～20cp; B solution is solidifying agent, comprises calcium chloride and oxidized starch, and wherein the purity of calcium chloride is 90%, adds pure water in calcium chloride and oxidized starch respectively and mixes to make aqueous solution, and the mass concentration of calcium chloride aqueous solution is 4 %~10%; the mass concentration of the aqueous solution of oxidized starch is 5%~12%, according to the mass ratio of 1:1, mixed at room temperature; The mass ratio of solution A to solution B is 4:1~5:1; after mixing, it can solidify rapidly and form strength within a few minutes to 2 hours.