CN113559453A - Slurry-coated flame-retardant slurry for gangue dump fire extinguishing and application thereof - Google Patents
Slurry-coated flame-retardant slurry for gangue dump fire extinguishing and application thereof Download PDFInfo
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- CN113559453A CN113559453A CN202111013455.3A CN202111013455A CN113559453A CN 113559453 A CN113559453 A CN 113559453A CN 202111013455 A CN202111013455 A CN 202111013455A CN 113559453 A CN113559453 A CN 113559453A
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- A62—LIFE-SAVING; FIRE-FIGHTING
- A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
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Abstract
The invention provides a slurry-coating flame-retardant slurry for gangue dump fire extinguishing and application thereof. The coating slurry flame-retardant slurry comprises the following raw materials in parts by weight: 60-80 parts of fly ash, 20-40 parts of desulfurized gypsum, 25-45 parts of lime powder, 20-30 parts of carbide slag, 10-15 parts of flame retardant and 270 parts of water 110-. The slurry-coated flame-retardant slurry has a good fire extinguishing effect, can achieve the purpose of quickly extinguishing and cooling a gangue dump, and a cured layer of the slurry-coated flame-retardant slurry after curing has good strength and good water resistance.
Description
Technical Field
The invention belongs to the technical field of metallurgical materials, and particularly relates to a slurry-coating flame-retardant slurry for gangue dump fire extinguishing and application thereof.
Background
The spontaneous combustion of the coal gangue dump is caused by that the heat released when the coal in the gangue and the pyrite are oxidized can promote the temperature rise of the gangue if the heat can not be completely dissipated into the surrounding environment, and the oxidation exothermic reaction can be further accelerated by the temperature rise. After reaching the critical temperature point, the oxidation reaction speed is rapidly accelerated, and at the moment, if sufficient oxygen supply can still be obtained, the gangue can quickly enter the spontaneous combustion state. The existence of a large amount of coal in the gangue maintains the long-time smoldering of the gangue pile, and the temperature gradient formed during the combustion of the coal accelerates the convection of air (namely the chimney effect), so that the gangue pile obtains enough oxygen for maintaining the combustion.
In the prior art, the fire extinguishing and cooling of the waste rock hills mainly comprise soil covering and water using. The disadvantages of the soil covering are: the engineering quantity is large, the environmental impact is large, the covering compactness is difficult to guarantee, and the fire extinguishing and cooling effects are not obvious. The method for extinguishing fire and cooling the gangue dump by using water is the most extensive and economic method at present, but the gangue dump has large pores and is not easy to store water, the phenomenon that solid-liquid phase in the slurry of the gangue dump is separated and water mostly runs away along a dominant channel exists when the gangue dump is simply used for extinguishing fire and cooling by using common slurry, or the water is immediately vaporized after reaching a high-temperature area, namely a fire area, so that the effect of quickly extinguishing fire and cooling cannot be achieved.
Therefore, there is a need to provide an improved solution to the above-mentioned deficiencies of the prior art.
Disclosure of Invention
The invention aims to provide a slurry-coated flame-retardant slurry for gangue dump extinguishment and application thereof, so as to achieve the purpose of quickly extinguishing and cooling the gangue dump.
In order to achieve the above purpose, the invention provides the following technical scheme:
the slurry-coated flame-retardant slurry for the gangue dump extinguishment comprises the following raw materials in parts by weight:
60-80 parts of fly ash, 20-40 parts of desulfurized gypsum, 25-45 parts of lime powder, 20-30 parts of carbide slag, 10-15 parts of flame retardant and 270 parts of water 110-.
As an optional embodiment, the liquid-solid ratio of the grouting flame-retardant slurry for extinguishing the gangue dump is 0.8-1.2.
As an optional embodiment, the slurry coating flame-retardant slurry for extinguishing the gangue dump comprises the following raw materials in percentage by mass:
fly ash: desulfurized gypsum: lime powder: carbide slag: flame retardant ═ (6-10): (2-4): (2-5): (2-3): (1-2).
The slurry-coating flame-retardant slurry for extinguishing the gangue dump is characterized in that the slurry-coating flame-retardant slurry is prepared from ammonium polyphosphate; preferably, the flame retardant is ammonium polyphosphate modified by a melamine formaldehyde resin.
As an optional embodiment, the coal ash is first-grade coal ash, and the particle size of the coal ash is less than 3 mm; the particle size of the lime powder is less than 3 mm; preferably, the particle size of the desulfurized gypsum is below 5mm, and the particle size of the carbide slag is below 5 mm.
As an optional embodiment, the size-covering flame-retardant slurry for fire extinguishing of the gangue dump further comprises 5-15 parts of a composite additive by mass, wherein the composite additive comprises polyacrylamide and carboxymethyl cellulose, and the mass ratio of the polyacrylamide to the carboxymethyl cellulose is 1 (1.5-3).
As an optional embodiment, the composite additive further comprises expandable graphite, and the mass ratio of the expandable graphite to the polyacrylamide is (0.5-1): 1.
as an optional example, the slurry for extinguishing fire of the gangue dump further comprises 5-10 parts by weight of polyethylene glycol 400.
The invention also provides application of the slurry-coated flame-retardant slurry for gangue dump fire extinguishing, wherein the slurry-coated flame-retardant slurry is used for gangue dump fire extinguishing and temperature reduction, and when the slurry-coated flame-retardant slurry is applied, the slurry-coated flame-retardant slurry is pumped and injected into the gangue dump which has spontaneous combustion, and the slurry fills gaps through permeation and diffusion, so that oxygen is isolated, and gangue combustion in a shallow region is blocked.
As an optional embodiment, the flow rate of the slurry coating flame-retardant slurry for extinguishing the gangue dump by pumping is 200-300L/min, and the pressure is 2-2.5 MPa.
Has the advantages that:
the raw materials of the slurry for the gangue dump fire-extinguishing are mostly industrial wastes, and comprise the fly ash and the desulfurized gypsum which are byproducts of a power plant and take coal as fuel, the waste lime powder, the carbide slag which is a byproduct of a PVC (polyvinyl chloride) plant, a fire retardant and water, so that the win-win effect of treating wastes with processes of wastes can be realized, and resources can be recycled. The preparation cost is low because the addition amount of solid waste in the raw materials of the slurry-coated flame-retardant slurry is large.
When the slurry-coated flame-retardant slurry is used for extinguishing fire and reducing the temperature of the spontaneous combustion gangue dump, the slurry-coated flame-retardant slurry is pumped and injected into the spontaneous combustion gangue dump, and the slurry permeates and diffuses to fill gaps, isolate oxygen and block the combustion of the gangue in a superficial area.
The fire extinguishing of the slurry covering fire-retardant slurry firstly takes the water in the slurry for cooling, and then the combination of the raw materials of the fly ash, the lime powder, the carbide slag and the fire retardant has the functions of adhering, wrapping and isolating oxygen on the spontaneous combustion coal gangue dump and has the function of retarding the fire of the spontaneous combustion coal gangue dump area. In the invention, the fly ash and the lime powder are used in a matching way, and CaO in the lime powder can excite the activity of the fly ash, so that SiO in fly ash particles2With Al2O3Silicate and aluminosilicate are generated in gangue fire extinguishing, so that the fire extinguishing effect is achieved. Ca (OH) in the lime powder liquid2Has certain inhibition effect, can reduce the oxygen absorption capacity of coal, and simultaneously has Ca (OH)2SO produced by combustion with gangue2And CO2The reaction can generate CaSO4And CaCO3They form a layer of stable covering on the surface of the gangue, and play a role in isolating air, thereby enhancing the fire extinguishing effect. The desulfurized gypsum provides a large amount of calcium base for the slurry, and the strength and the water resistance of a cured layer of the slurry-coated flame-retardant slurry after curing are improved. In addition, carbide slag, i.e. calcium carbide CaC2The residue after hydrolysis contains a small amount of active SiO2With Al2O3Calcium carbide hydrolysate Ca (OH)2Small amount of active SiO2With Al2O3As a material for extinguishing the gangue dump, the fire extinguishing material has good fire extinguishing effect.
Tests prove that a cured layer of the slurry-coated flame-retardant slurry has good strength, the 28d compressive strength is 3-5MPa, the slurry-coated flame-retardant slurry has a good slope protection effect, the hillock can be prevented from sliding, and the stability of the hillock is improved.
Tests prove that the curing layer of the slurry-coated flame-retardant slurry has good water resistance, the softening coefficient of the test block is not lower than 0.9, rainwater can be effectively prevented from permeating into a gangue dump, and the possibility of landslide of the gangue dump is reduced; and harmful elements in the gangue dump can be prevented from being dissolved into rainwater and permeating into underground water, so that the underground water is protected.
When the slurry is applied to the gangue dump for fire extinguishing, the temperature of the gangue dump which is spontaneously combusted can be reduced to normal temperature within about 60 days, the temperature reduction is fast, and the temperature reduction effect is good.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments that can be derived by one of ordinary skill in the art from the embodiments given herein are intended to be within the scope of the present invention.
The present invention will be described in detail with reference to examples. It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
The slurry-covering flame-retardant slurry disclosed by the invention is prepared from fly ash, desulfurized gypsum, lime powder, carbide slag, a flame retardant and water, wherein the fly ash and the desulfurized gypsum are from a power plant, the lime powder is from waste lime of a lime plant, the carbide slag is from a PVC (polyvinyl chloride) plant, most of the fly ash and the desulfurized gypsum are industrial solid wastes, the slurry-covering flame-retardant slurry is easy to obtain, and the cost is low. And the water in the raw materials can be industrial wastewater or domestic wastewater, so that the cost is low, the win-win effect of treating wastes with wastes can be realized, and the resources are recycled.
The invention provides a slurry-coated flame-retardant slurry for gangue dump fire extinguishing, which comprises the following raw materials in parts by weight:
60-80 parts (such as 60 parts, 65 parts, 70 parts, 75 parts or 80 parts) of fly ash, 20-40 parts (such as 20 parts, 25 parts, 30 parts, 35 parts or 40 parts) of desulfurized gypsum, 25-45 parts (such as 25 parts, 30 parts, 35 parts, 40 parts or 45 parts) of lime powder, 20-30 parts (such as 20 parts, 22 parts, 24 parts, 26 parts, 28 parts or 30 parts) of carbide slag, 10-15 parts (such as 10 parts, 11 parts, 12 parts, 13 parts, 14 parts or 15 parts) of flame retardant and 270 parts (such as 110 parts, 130 parts, 150 parts, 170 parts, 210 parts, 230 parts, 250 parts or 270 parts) of water 110 and materials.
The fly ash is a particle group formed by mixing and accumulating various particles with different properties, and has no gelling property. But when water exists at normal temperature, the water can react with lime chemically to generate hydration products with gelling property, namely the hydration products have volcanic ash activity. These hydrated products generally harden immediately in air and graduallyHas hydraulic property, and the main hydration products are calcium silicate hydrate and calcium aluminate hydrate gel. The fly ash is matched with lime, CaO can excite the activity of the fly ash, so that SiO in fly ash particles2With Al2O3Silicate and aluminosilicate are generated in the gangue dump fire extinguishing process, so that the fire extinguishing effect is achieved.
The main component of the desulfurized gypsum is CaSO4·2H2O, CaSO thereof4·2H2The content of O is over 90 percent, the purity is higher than that of natural gypsum, and the main impurity is CaCO3、Al2O3And SiO2And the like, the addition of the desulfurized gypsum provides a large amount of calcium base to the slurry, improving the strength and water resistance of a cured layer of the slurry.
Addition of lime powder, Ca (OH) in lime liquid2Has certain inhibition effect and can reduce the oxygen absorption capacity of the gangue. Meanwhile, Ca (OH)2SO produced by combustion with gangue2And CO2Reaction to produce CaSO4And CaCO3They form a stable covering on the surface of the gangue, and play a role in isolating air.
Carbide slag, i.e. calcium carbide CaC2The residue after hydrolysis contains a small amount of active SiO2With Al2O3The chemical reaction equation of calcium carbide hydrolysis is CaC2+2H2O＝C2H2+Ca(OH)2Therefore, the carbide slag contains Ca (OH)2And a small amount of active SiO2With Al2O3The fire-extinguishing material is used as a fire-extinguishing material for the waste rock mountain to generate silicate, aluminosilicate and calcium carbonate, and has good fire-extinguishing effect.
The flame retardant can form a glassy or stable foam covering layer at high temperature, isolate oxygen, and has the functions of heat insulation, oxygen isolation and prevention of combustible gas from escaping outwards, thereby achieving the purpose of flame retardance.
The fire extinguishing of the slurry covering fire-retardant slurry firstly takes the water in the slurry for cooling, and then the combination of the raw materials of the fly ash, the lime powder, the carbide slag and the fire retardant has the functions of adhering, wrapping and isolating oxygen on the spontaneous combustion coal gangue dump and has the function of retarding the fire of the spontaneous combustion coal gangue dump area. In addition, the cured layer of the slurry-coated flame-retardant slurry has higher strength and water resistance, can improve the stability of the waste rock, prevent rainwater from permeating into the waste rock and reduce the possibility of landslide of the waste rock.
In the embodiment of the invention, the liquid-solid ratio of the size-coating flame-retardant slurry is 0.8-1.2 (such as 0.8, 0.9, 1.0, 1.1 or 1.2). The slurry with the liquid-solid ratio has better fluidity and pumping time, and the compressive strength of a cured layer of the slurry after curing is higher.
In the specific embodiment of the invention, the solid raw materials in the slurry-coating flame-retardant slurry meet the following mass ratio: fly ash: desulfurized gypsum: lime powder: carbide slag: flame retardant ═ (6-10): (2-4): (2-5): (2-3): (1-2). Preferably, the ratio of fly ash: desulfurized gypsum: lime powder: carbide slag: the fire retardant is 9:3:3:3:1, the slurry coating fire-retardant slurry of the solid raw materials with the mass ratio can extinguish fire more quickly and effectively, and the compressive strength of a cured layer of the slurry is higher.
In the specific embodiment of the invention, the flame retardant is ammonium polyphosphate which is an intumescent flame retardant, has the characteristics of no halogen and excellent flame retardant property, and can play a better inhibiting role by combining solid wastes in raw materials.
Preferably, the flame retardant is ammonium polyphosphate modified by a melamine formaldehyde resin. The melamine formaldehyde resin has good flame retardant property, and the melamine formaldehyde resin is modified and wrapped on the outer surface of the ammonium polyphosphate, so that the moisture absorption rate of the ammonium polyphosphate can be reduced, the deliquescence reaction of the ammonium polyphosphate is prevented, and meanwhile, the melamine formaldehyde resin and the ammonium polyphosphate have better inhibition property in combination, so that the water retention and flame retardant property of the slurry-coated flame retardant slurry are improved.
In an optional embodiment, the fly ash is first-grade fly ash, high-calcium fly ash, and calcium and Al in the high-calcium fly ash2O3The reaction produces calcium silicate hydrate and calcium aluminate hydrate, which can improve the strength of the cured layer.
The solid waste raw material of the slurry-coated flame-retardant slurry has small particle size, and only needs simple grinding when in use, thereby saving a large amount of manpower and material resources. In the specific embodiment of the invention, the granularity of the fly ash is below 3mm, the granularity of the lime powder is below 3mm, the granularity of the desulfurized gypsum is below 5mm, and the granularity of the carbide slag is below 5 mm.
Further, in the embodiment of the invention, the size-coating flame-retardant slurry further comprises 5-15 parts (for example, 5 parts, 7 parts, 10 parts, 12 parts or 15 parts) of a composite additive by mass, wherein the composite additive comprises polyacrylamide and carboxymethyl cellulose, and the mass ratio of the polyacrylamide to the carboxymethyl cellulose is 1 (1.5-3) (for example, 1:1.5, 1:1.7, 1:2, 1:2.2, 1:2.5, 1:2.7 or 1: 3). The carboxymethyl cellulose is heated to 50-60 ℃ to form gel, the polyacrylamide and the carboxymethyl cellulose can form a three-dimensional polymer network of a large number of water molecules, the flowing of the mixture can be stopped, rigid gel is formed, the water in the material is effectively preserved, the waterproof material cracks, the carboxymethyl cellulose and the polyacrylamide can form colloid at a certain temperature, the colloid contains water, the water can reduce the temperature of a fire area of the gangue dump during evaporation, meanwhile, the colloid is attached to the surface of the gangue dump after reaching stability to form a compact film, the film can prevent the gangue dump from contacting with oxygen to further prevent the oxidation of the gangue, for spontaneous combustion fire of the gangue dump, the colloid can quickly reduce the temperature of the fire area, wrap the gangue dump and isolate oxygen, the fire can be extinguished quickly, and due to the plugging effect of the colloid, air leakage channels can be quickly plugged, preventing the release of toxic and harmful gases.
It can be understood that the composite admixture of polyacrylamide and carboxymethyl cellulose is added into the raw materials of the sizing flame-retardant slurry, so that the fire can be extinguished more quickly and effectively.
Further, in the embodiment of the invention, the composite admixture further comprises expandable graphite, and the mass ratio of the expandable graphite to the polyacrylamide is (0.5-1): 1 (e.g., 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, or 1: 1). Expandable graphite is a crystalline compound formed by inserting a non-carbonaceous reactant between graphite layers by physical or chemical means. When the expandable graphite meets high temperature, the interlaminar compound is decomposed and begins to expand, and the expandable graphite expands completely at 1000 ℃, and the expansion multiple can reach more than 200 times. The expanded graphite forms a very good heat insulation layer, can effectively insulate heat, and has the characteristics of low heat release rate, small mass loss and small smoke yield in fire. When the moisture in the composite covering slurry flame-retardant slurry is completely evaporated, the aggregate in the composite covering slurry can be rapidly expanded under the high-temperature condition, so that a high-temperature fire source in the coal gangue dump is tightly wrapped, the air leakage crack is secondarily plugged, and the fire source is effectively prevented from spreading.
The size-covering flame-retardant slurry also comprises 5-10 parts (such as 5 parts, 6 parts, 7 parts, 8 parts, 9 parts or 10 parts) of polyethylene glycol 400 by mass. Polyethylene glycol 400 is a dispersant, can play the effect of dispersing solid particle in the raw materials, impels the even abundant reaction that ettringite formed, and polyethylene glycol 400 can adsorb unnecessary free water simultaneously, has ensured high solid water, high compactness and isolated oxygen effectively to make the fire-retardant thick liquid of covering thick liquid have rapid cooling and block the function of putting out a fire.
The invention also provides application of the slurry-coated flame-retardant slurry for gangue dump fire extinguishing, wherein the slurry-coated flame-retardant slurry is used for gangue dump fire extinguishing and temperature reduction, and when the slurry-coated flame-retardant slurry is applied, the slurry-coated flame-retardant slurry is pumped and injected into the gangue dump which generates spontaneous combustion, and the slurry fills gaps through permeation and diffusion, isolates oxygen and blocks gangue combustion in a superficial area.
Due to different stacking densities of the gangue, in order to ensure the temperature reduction and fire extinguishing effects of the slurry-coated fire-retardant slurry, the slurry-coated fire-retardant slurry is pumped and injected at a flow rate of 200 and 300L/min (such as 200L/min, 220L/min, 250L/min, 270L/min or 30L/min) and a pressure of 2-2.5MPa (such as 2MPa, 2.1MPa, 2.2MPa, 2.3MPa, 2.4MPa or 2.5 MPa).
The invention is used for the gangue dump fire extinguishing coating fire-retardant slurry and the application thereof are explained in detail by the specific embodiment.
In the following examples and comparative examples, the fluidity of the slurry was measured by using a mortar fluidity meter according to the requirements of "mortar fluidity measuring method" GB/T2419-2005 with reference to the mortar fluidity measuring method. The fluidity is expressed in terms of the average diameter (mm) of the cement mortar spread on the flow table, and the larger the average diameter, the larger the fluidity of the cement mortar, and the better the fluidity.
The water precipitation rate refers to the ratio of the volume of precipitated water to the volume of the original slurry after the slurry is solidified. The water precipitation rate of the slurry reflects the stability of the slurry, is an important performance index of the slurry, and generally requires a smaller water precipitation rate for production and application. The lower the water separation rate, the better the slurry stability, and the slurry having a water separation rate of less than 5% for 6 hours is defined as a stable slurry, and the water separation rate of 6 hours is used as an index for evaluating the slurry stability. The method for testing the water separating rate of the slurry comprises the following steps of taking a 500ml measuring cylinder, pouring about 400ml of the slurry, recording the volume of the slurry as V1, standing for 6 hours, observing the separation above the slurry, and reading the volume V2 of the separated water, wherein the water separating rate alpha is the ratio of V2 to V1.
The compressive strength of the cured layer of the mortar coating material is tested according to GB/T17671-1999 Cement mortar Strength test method (ISO method), and the mortar is subjected to pressure by using an unconfined uniaxial press. In the test, a 70.7 multiplied by 70.7mm triple mortar test mold is used, the sample is demoulded and then placed into a standard curing box for curing at constant temperature and humidity of cement, and the compressive strength of the sample with the age of 28 days is measured. In each group of experiments, the compressive strength of the three test blocks is respectively tested, and the average value is taken as the test result of one group, and the test result is accurate to 0.01 MPa. During the test, the individual test blocks have larger or smaller reading (plus or minus 20%), and should be eliminated to obtain the average value of the residual blocks.
Example 1
The application of the slurry-coating flame-retardant slurry for fire extinguishing of the gangue dump provided by the embodiment comprises the following steps:
(1) according to the mass parts, 60 parts of fly ash, 20 parts of desulfurized gypsum, 25 parts of lime powder, 20 parts of carbide slag, 10 parts of melamine formaldehyde resin modified ammonium polyphosphate and 160 parts of water are weighed and uniformly stirred to obtain the slurry-coated flame-retardant slurry. The fluidity measured by cement mortar fluidity measuring method is 94mm, and the water precipitation rate of the slurry after 6h is 3.8%.
(2) Pouring the slurry into a mortar triple test mould of 70.7 multiplied by 70.7, placing the slurry and the test mould in an environment with the temperature (20 +/-2) DEG C and the relative humidity more than or equal to 50%, demoulding after 48h, placing the test block in a curing box with the temperature (20 +/-1) DEG C and the relative humidity not less than 90%, and detecting that the compressive strength of the test block in 28d period is 4.2MPa and the softening coefficient is 0.91 after 28 d.
Example 2
The application of the slurry-coating flame-retardant slurry for fire extinguishing of the gangue dump provided by the embodiment comprises the following steps:
(1) according to the mass parts, 70 parts of fly ash, 25 parts of desulfurized gypsum, 30 parts of lime powder, 25 parts of carbide slag, 12 parts of melamine formaldehyde resin modified ammonium polyphosphate, 3 parts of polyacrylamide, 5 parts of carboxymethyl cellulose, 2 parts of expandable graphite, 5 parts of polyethylene glycol 400 and 200 parts of water are weighed and uniformly stirred to obtain the slurry-covered flame-retardant slurry. The fluidity measured by cement mortar fluidity measuring method is 96mm, and the water precipitation rate of the slurry after 6h is 3.6%.
(2) Pouring the slurry into a mortar triple test mold of 70.7 multiplied by 70.7, placing the slurry and the test mold in an environment with the temperature (20 +/-2) DEG C and the relative humidity more than or equal to 50%, demolding after 48h, placing the test block in a curing box with the temperature (20 +/-1) DEG C and the relative humidity not less than 90%, and detecting that the compressive strength of the test block in 28d period is 4.6MPa and the softening coefficient is 0.92 after 28 d.
Example 3
The application of the slurry-coating flame-retardant slurry for fire extinguishing of the gangue dump provided by the embodiment comprises the following steps:
(1) weighing 80 parts of fly ash, 40 parts of desulfurized gypsum, 45 parts of lime powder, 30 parts of carbide slag, 15 parts of melamine formaldehyde resin modified ammonium polyphosphate, 4 parts of polyacrylamide, 7 parts of carboxymethyl cellulose, 4 parts of expandable graphite, 10 parts of polyethylene glycol 400 and 270 parts of water by mass, and uniformly stirring to obtain the slurry-covered flame-retardant slurry. The fluidity measured by cement mortar fluidity measuring method is 98mm, and the water precipitation rate of the slurry after 6h is 3.9%.
(2) Pouring the slurry into a mortar triple test mold of 70.7 multiplied by 70.7, placing the slurry and the test mold in an environment with the temperature (20 +/-2) DEG C and the relative humidity more than or equal to 50%, demolding after 48h, placing the test block in a curing box with the temperature (20 +/-1) DEG C and the relative humidity not less than 90%, and detecting that the compressive strength of the test block in 28d period is 4.8MPa and the softening coefficient is 0.93 after 28 d.
Example 4
The method comprises the steps of carrying out a field test on a certain spontaneous combustion gangue dump, selecting a spontaneous combustion area of 2000 square meters, detecting that the internal temperature of a coal gangue pile is 432 ℃ through a thermocouple, detecting the temperature again at the later stage of embedded treatment of a thermocouple probe, using the slurry-coated flame-retardant slurry obtained in the example 2 for fire extinguishing and cooling of the gangue dump, and when the slurry-coated flame-retardant slurry is applied, pumping the slurry-coated flame-retardant slurry into the spontaneous combustion gangue dump, wherein the flow rate of the infusion is 250L/min, the pressure is 2.5MPa, and the slurry permeates and diffuses to fill gaps, isolate oxygen and block gangue combustion in a superficial area. And after the slurry is cured, spraying water on the surface of the slurry-coated cured layer for 3-4 times after 72 hours, and sampling and detecting the compressive strength of the slurry to be 4.3MPa at the 28 th day after construction. And (5) detecting that the temperature readings of the pre-buried thermocouples are continuously reduced to 302 ℃, 126 ℃ and 32 ℃ after 30d, 45d and 60d of the slurry covering treatment, and the temperature of the spontaneous combustion area of the coal gangue pile is approximately normal after 60 d.
Example 5
The method comprises the steps of carrying out a field test on a certain spontaneous combustion gangue dump, selecting a spontaneous combustion area of 1000 square meters, detecting that the internal temperature of a coal gangue pile is 382 ℃ through a thermocouple, detecting the temperature again at the later stage of embedded treatment of a thermocouple probe, using the slurry-coated flame-retardant slurry obtained in the example 3 for fire extinguishing and cooling of the gangue dump, and when the slurry-coated flame-retardant slurry is applied, pumping the slurry-coated flame-retardant slurry into the spontaneous combustion gangue dump, wherein the flow rate of the infusion is 250L/min, the pressure is 2.5MPa, and the slurry permeates and diffuses to fill gaps, isolate oxygen and block gangue combustion in a superficial area. And after the slurry is cured, spraying water on the surface of the slurry-coated cured layer for 3-4 times after 72 hours, and sampling and detecting the compressive strength of the slurry to be 4.8MPa at the 28 th day after construction. And (3) detecting the temperature readings of the pre-buried thermocouples at 30d, 45d and 60d after the slurry covering treatment, and continuously reducing the temperature readings to 278 ℃, 106 ℃ and 30 ℃, wherein the temperature of the spontaneous combustion area of the coal gangue pile tends to be normal after 60 d.
Example 6
The application of the slurry coating flame-retardant slurry for extinguishing the gangue dump provided by the embodiment has the same steps as those of the embodiment 1, and only differs in raw material selection.
In this embodiment, the influence of the addition ratio of fly ash, desulfurized gypsum, carbide slag and lime powder to the slurry performance in the raw materials is studied, the addition amount of the flame retardant is set to be 10 parts, the addition amount of the cement is 10 parts, the addition amount of the composite additive is 15 parts, and the composite additive includes: 4 parts of polyacrylamide, 8 parts of sodium carboxymethyl cellulose silicate and 3 parts of expandable graphite, wherein the liquid-solid ratio is 1.2, and standard curing is adopted in the curing mode. Comparing the influence of the addition ratio of the fly ash, the desulfurized gypsum, the lime powder and the carbide slag on the performance of the slurry, namely 3:1:1:1, 3:1:2:1, 3:2:1:1 and 4:2:2:1, see table 1 specifically, and table 1 shows the test result of the influence of the addition ratio of the fly ash, the desulfurized gypsum, the carbide slag and the lime powder on the performance of the slurry.
TABLE 1 test results of the influence of the addition ratio of fly ash, desulfurized gypsum, lime powder and carbide slag on the slurry properties
As can be seen from Table 1, as the addition amount of the fly ash is increased, the fluidity of the slurry is increased continuously from 92mm to 96mm, and the fluidity is kept above 90mm, so that the slurry has better fluidity and can meet the pipeline transportation. Through analysis, the reason for the increase of the fluidity is that the fly ash particles are spherical, the surface is compact and smooth, the particle shape and the surface state of the fly ash particles play a role of a ball bearing in the composite slurry, the increase of the fluidity due to the increase of the content of the fly ash indicates that the contribution of the fly ash to the fluidity in a researched system is larger than that of other raw materials, the addition of the other raw materials reduces the slurry consistency to a certain extent, and the fluidity tends to be reduced.
And with the increase of the addition amount of the fly ash, the water precipitation rate of the slurry is reduced from 3.8% to 3.4% after 6 hours, and the reduction trend is not large. And the water precipitation rate of the slurry is less than 5%, so that the slurry is stable.
Meanwhile, as can be seen from table 1, the compressive strength increases with age, and when the fly ash, the desulfurized gypsum, the lime powder and the carbide slag are added in a ratio of 3:1:1:1, the compressive strength is highest for different ages.
Comparative example 1
The difference between the comparative example and the example 2 is that the coating flame-retardant slurry does not contain the ammonium polyphosphate modified by the melamine formaldehyde resin, the polyacrylamide, the carboxymethyl cellulose, the expandable graphite and the polyethylene glycol 400, and other raw materials are the same as the example 2.
(1) The fluidity of the composite gelled grouting material slurry is measured to be 82mm by using a cement mortar fluidity tester, and the water precipitation rate of the slurry after 6h is 4.8%.
(2) Pouring the slurry into a mortar triple test mould of 70.7 multiplied by 70.7, placing the slurry and the test mould in an environment with the temperature (20 +/-2) DEG C and the relative humidity more than or equal to 50%, demoulding after 48h, placing the test block in a curing box with the temperature (20 +/-1) DEG C and the relative humidity not less than 90%, and detecting that the compressive strength of the test block in 28d period is 3.6MPa and the softening coefficient is 0.91 after 28 d.
(4) The method comprises the steps of carrying out field test on a certain spontaneous combustion gangue dump, selecting a spontaneous combustion area of 2000 square meters, detecting that the internal temperature of a coal gangue pile is 432 ℃ through a thermocouple, detecting the temperature again at the later stage of embedded treatment of a thermocouple probe, using the slurry-coated flame-retardant slurry obtained in the comparative example 1 for fire extinguishing and cooling of the gangue dump, and when the slurry-coated flame-retardant slurry is applied, pumping the slurry-coated flame-retardant slurry into the spontaneous combustion gangue dump, wherein the flow rate of infusion is 250L/min, the pressure is 2.5MPa, and the slurry permeates and diffuses to fill gaps, isolate oxygen and block gangue combustion in a shallow surface area. And after the slurry is cured, spraying water on the surface of the slurry-coated cured layer for 3-4 times after 72 hours, and sampling and detecting the compressive strength of the slurry to be 3.8MPa at the 28 th day after construction. And (3) detecting the temperature readings of the pre-buried thermocouples at 30d, 45d, 60d and 75d after the slurry covering treatment, and continuously reducing the temperature readings to 324 ℃, 296 ℃, 118 ℃ and 33 ℃, wherein the temperature of the spontaneous combustion area of the coal gangue pile tends to be normal after 75 d.
Therefore, compared with the comparative example 1, in the example 2, because a proper amount of ammonium polyphosphate modified by melamine formaldehyde resin, polyacrylamide, carboxymethyl cellulose, expandable graphite and polyethylene glycol 400 are added into the composite cementitious guniting material slurry, the slurry has better fluidity, better 28d compressive strength and quicker fire extinguishing and temperature reduction.
In summary, the following steps: the raw materials of the slurry for the gangue dump fire-extinguishing are mostly industrial wastes, and comprise the fly ash and the desulfurized gypsum which are byproducts of a power plant and take coal as fuel, the waste lime powder, the carbide slag which is a byproduct of a PVC (polyvinyl chloride) plant, a fire retardant and water, so that the win-win effect of treating wastes with processes of wastes can be realized, and resources can be recycled. The preparation cost is low because the addition amount of solid waste in the raw materials of the slurry-coated flame-retardant slurry is large.
When the slurry-coated flame-retardant slurry is used for extinguishing fire and reducing the temperature of the spontaneous combustion gangue dump, the slurry-coated flame-retardant slurry is pumped and injected into the spontaneous combustion gangue dump, and the slurry permeates and diffuses to fill gaps, isolate oxygen and block the combustion of the gangue in a superficial area.
The fire extinguishing of the slurry covering fire-retardant slurry firstly takes the water in the slurry for cooling, and then the combination of the raw materials of the fly ash, the lime powder, the carbide slag and the fire retardant has the functions of adhering, wrapping and isolating oxygen on the spontaneous combustion coal gangue dump and has the function of retarding the fire of the spontaneous combustion coal gangue dump area. In the invention, the fly ash and the lime powder are used in a matching way, and CaO in the lime powder can excite the activity of the fly ash, so that SiO in fly ash particles2With Al2O3Silicate and aluminosilicate are generated in gangue fire extinguishing, so that the fire extinguishing effect is achieved. Ca (OH) in the lime powder liquid2Has certain inhibition effect, can reduce the oxygen absorption capacity of coal, and simultaneously has Ca (OH)2SO produced by combustion with gangue2And CO2The reaction can generate CaSO4And CaCO3They form a layer of stable covering on the surface of the gangue, and play a role in isolating air, thereby enhancing the fire extinguishing effect. The desulfurized gypsum provides a large amount of calcium base for the slurry, and the strength and the water resistance of a cured layer of the slurry-coated flame-retardant slurry after curing are improved. In addition, carbide slag, i.e. calcium carbide CaC2The residue after hydrolysis contains a small amount of active SiO2With Al2O3Calcium carbide hydrolysate Ca (OH)2Small amount of active SiO2With Al2O3As a material for extinguishing the gangue dump, the fire extinguishing material has good fire extinguishing effect.
Tests prove that a cured layer of the slurry-coated flame-retardant slurry has good strength, the 28d compressive strength is 3-5MPa, the slurry-coated flame-retardant slurry has a good slope protection effect, the hillock can be prevented from sliding, and the stability of the hillock is improved.
Tests prove that the curing layer of the slurry-coated flame-retardant slurry has good water resistance, the softening coefficient of the test block is not lower than 0.9, rainwater can be effectively prevented from permeating into a gangue dump, and the possibility of landslide of the gangue dump is reduced; and harmful elements in the gangue dump can be prevented from being dissolved into rainwater and permeating into underground water, so that the underground water is protected.
When the slurry is applied to the gangue dump for fire extinguishing, the temperature of the gangue dump which is spontaneously combusted can be reduced to normal temperature within about 60 days, the temperature reduction is fast, and the temperature reduction effect is good.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The slurry-coated flame-retardant slurry for fire extinguishment of the gangue dump is characterized by comprising the following raw materials in parts by mass:
60-80 parts of fly ash, 20-40 parts of desulfurized gypsum, 25-45 parts of lime powder, 20-30 parts of carbide slag, 10-15 parts of flame retardant and 270 parts of water 110-.
2. The grout for gangue dump fire extinguishing according to claim 1, wherein the grout has a liquid-to-solid ratio of 0.8-1.2.
3. The coating fire-retardant slurry for gangue dump fire extinguishing according to claim 1, wherein the following raw materials are satisfied in the coating fire-retardant slurry by mass ratio:
fly ash: desulfurized gypsum: lime powder: carbide slag: flame retardant ═ (6-10): (2-4): (2-5): (2-3): (1-2).
4. The slurry-coating flame-retardant slurry for gangue dump fire extinguishing according to claim 1, wherein the flame retardant is ammonium polyphosphate;
preferably, the flame retardant is ammonium polyphosphate modified by a melamine formaldehyde resin.
5. The coating fire-retardant slurry for gangue dump fire extinguishing according to claim 1, wherein the fly ash is first-grade fly ash, and the particle size of the fly ash is less than 3 mm; the particle size of the lime powder is less than 3 mm;
preferably, the particle size of the desulfurized gypsum is below 5mm, and the particle size of the carbide slag is below 5 mm.
6. The pulp-coating flame-retardant slurry for extinguishing fire of the gangue dump according to any one of claims 1 to 5, wherein the pulp-coating flame-retardant slurry further comprises 5 to 15 parts by weight of a composite additive, the composite additive comprises polyacrylamide and carboxymethyl cellulose, and the mass ratio of the polyacrylamide to the carboxymethyl cellulose is 1 (1.5-3).
7. The grout for gangue dump fire extinguishing and fire retardant slurry of claim 6, wherein the composite additive further comprises expandable graphite, and the mass ratio of the expandable graphite to the polyacrylamide is (0.5-1): 1.
8. the coating fire-retardant slurry for gangue dump fire extinguishing according to any one of claims 1 to 6, wherein the coating fire-retardant slurry further comprises 5 to 10 parts by weight of polyethylene glycol 400.
9. The use of the slurry-coated flame-retardant slurry for extinguishing a gangue dump according to any one of claims 1 to 8, wherein the slurry-coated flame-retardant slurry is used for extinguishing and cooling the gangue dump, and when the slurry-coated flame-retardant slurry is used, the slurry-coated flame-retardant slurry is pumped into the gangue dump which spontaneously combusts, and the slurry fills gaps by permeation and diffusion, isolates oxygen and blocks gangue combustion in a shallow area.
10. The application of the slurry-coating fire-retardant slurry for gangue dump fire extinguishing as claimed in claim 9, wherein the slurry-coating fire-retardant slurry is pumped and injected at a flow rate of 200 and 300L/min and a pressure of 2-2.5 MPa.
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