CN114214072B - Heavy metal contaminated soil curing agent and preparation method and application thereof - Google Patents
Heavy metal contaminated soil curing agent and preparation method and application thereof Download PDFInfo
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- CN114214072B CN114214072B CN202111530667.9A CN202111530667A CN114214072B CN 114214072 B CN114214072 B CN 114214072B CN 202111530667 A CN202111530667 A CN 202111530667A CN 114214072 B CN114214072 B CN 114214072B
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Abstract
The invention discloses a heavy metal contaminated soil curing agent which comprises 60-88% by mass of slag powder and 9-34% by mass of desulfurized gypsum and 3-12% by mass of an activator, wherein the activator is biomass ash obtained by treating phoenix tree leaves, rice hulls and Chinese fir. The invention also discloses a preparation method and application of the curing agent. The method takes the phoenix tree leaf ash, the rice hull ash and the cedar ash as the excitant, and the aims of solidifying the heavy metal ions and preventing the heavy metal ions from leaching and migrating can be achieved by utilizing the characteristics that the phoenix tree leaf ash has the function of adjusting the pH value of the mixture, the rice hull ash has important influence on the geological polymerization process and the cedar ash provides sulfate ions and has the function of adsorption; the curing agent has the characteristics of environmental protection, low cost and good curing effect.
Description
Technical Field
The invention belongs to the technical field of solid waste treatment, and particularly relates to a heavy metal contaminated soil curing agent, and a preparation method and application thereof.
Background
The solidification treatment is a technical means for mixing the polluted soil with a cementing material and reducing leaching characteristics in the soil by physical and chemical means so as to meet the requirement of the environment and achieve the purpose of treating the polluted soil. It is one of the widely applied technologies for treating soil heavy metal pollution at home and abroad at present. Compared with other technologies, the curing treatment technology is mature, economical and applicable, strong in compatibility with soil, controllable in repair period and good in long-term stability. When the method is used for repairing industrial polluted sites, the migration of pollutants can be effectively controlled. At present, the technology for treating heavy metal polluted soil by a stable curing method in China is still in a development stage, and scholars study the effects of different additives on the treatment of heavy metal ion pollution, wherein the curing effect of cement on heavy metal is very effective in an attempted curing agent. However, the production of cement consumes a lot of resources and energy and produces a large amount of CO 2、SO2CO, solid waste, and industrial wastewater, pose significant environmental problems. The search for a substitute material of cement is an important research content in the direction of heavy metal contaminated soil remediation.
Slag is a solid waste discharged in the iron-making process. In recent years, with the continuous development and growth of steel enterprises, the slag yield is gradually increased year by year, and the ecological environment is seriously damaged. At present, slag is mainly used for refining and processing slag cement, slag powder, slag portland cement, blast furnace slag and the like. The yield of the desulfurized gypsum, which is an industrial byproduct obtained after the flue gas of a power plant is desulfurized, is more than 8000 ten thousand tons until now and is still increasing continuously. The utilization of Chinese desulfurized gypsum is mainly carried out in the following aspects: the cement modifier is used as a cement modifying material to adjust the setting time and improve the performance of the cement modifier; gypsum mortar and building blocks; soil modification and the like. Due to the reasons of technology, geography, economy and the like, the solid waste is low in effective utilization rate and can be accumulated in a large amount, so that the investment and operation cost of enterprises are increased, and serious potential safety hazards, ecological environment pollution and the like are caused.
Disclosure of Invention
The invention aims to solve the first technical problem of providing a heavy metal contaminated soil curing agent, which takes slag, desulfurized gypsum and biomass ash as main raw materials, so that the aims of treating wastes with processes of wastes against one another and changing waste into valuables can be achieved, and the requirement of green cycle low-carbon development in China is met.
The second technical problem to be solved by the invention is to provide a preparation method of the curing agent.
The third technical problem to be solved by the invention is to provide the application of the curing agent in curing heavy metals.
In order to solve the first technical problem, the technical scheme of the invention is as follows:
the heavy metal contaminated soil curing agent comprises 60-88% by mass and 9-34% by mass of slag powder, desulfurized gypsum and an activator, wherein the activator is biomass ash obtained by processing Chinese parasol tree leaves, rice husks and Chinese fir and is 3-12% by mass.
In order to solve the second technical problem, the preparation method of the heavy metal contaminated soil curing agent designed by the invention comprises the following steps:
1) drying and crushing the phoenix tree leaves, the rice hulls and the Chinese fir respectively to obtain corresponding biological chips, namely the phoenix tree leaf chips, the rice hull chips and the Chinese fir chips;
2) respectively putting the three biological crumbs into a muffle furnace to be burned to obtain corresponding biomass ash (namely Chinese parasol tree leaf ash, rice hull ash and cedar ash); wherein, the phoenix tree leaf scraps are burned at the temperature of 700-820 ℃; firing the rice hull scraps at the temperature of 500-600 ℃; firing the cedar chips at the temperature of 500-550 ℃;
3) Drying and uniformly mixing the slag powder and the desulfurized gypsum to obtain a dry mixture;
4) uniformly mixing the biomass ash obtained in the step 2) with the dry mixture obtained in the step 3) to obtain the heavy metal contaminated soil curing agent;
mixing the biomass ash obtained in the step 4) according to the mass ratio of (1-4) to obtain an exciting agent, wherein the exciting agent and the components obtained in the step 3) are contained in the prepared heavy metal polluted soil curing agent according to the mass percentage: 60-88% of slag powder, 9-34% of desulfurized gypsum and 3-12% of excitant.
In step 1) of the present invention, the apparatus used for the pulverization is preferably a ball mill.
In the step 2), the firing temperatures of the phoenix tree leaf scraps, the rice hull scraps and the cedar sawdust in the muffle furnace are 700-820 ℃, 500-600 ℃ and 500-550 ℃ respectively.
In the step 4), the drying temperature is 100-110 ℃.
In order to solve the third technical problem, the invention provides a method for solidifying heavy metals in heavy metal polluted soil by using the heavy metal polluted soil solidifying agent prepared by the method, which comprises the following steps:
1) and uniformly mixing the heavy metal contaminated soil curing agent and the heavy metal contaminated soil at normal temperature to obtain a mixture, wherein the mass ratio of the heavy metal contaminated soil and the heavy metal contaminated soil curing agent in the mixture is respectively as follows: 70-90% and 10-30%;
2) Adding water into the mixture obtained in the step 1) for mixing, so that the water content of the mixture is 25-30%;
3) and (3) stirring, compacting and molding the mixture after adding water to obtain a solidified block, and curing for 7-28 days under standard curing conditions of (20 +/-2) DEG C and humidity of 95 percent.
The heavy metal in the heavy metal contaminated soil at least comprises any one of copper, cadmium, chromium or lead ions.
Compared with the traditional heavy metal polluted soil curing agent, the slag powder, the desulfurized gypsum and the biomass ash based heavy metal polluted soil curing agent has the following remarkable beneficial effects:
1) the invention is environment-friendly, properly controlled in cost and good in curing effect.
2) The method takes the phoenix tree leaf ash, the rice hull ash and the cedar ash as the excitant, and mainly utilizes the physicochemical characteristics of the biomass ash. The phoenix tree leaves are burnt into ash at the temperature of 700-820 ℃, the content of alkali metal in the main component accounts for 12-15%, and CaO accounts for 29-35% of ash component, so that the effect of adjusting the pH value of the mixture is achieved; the rice hull is burnt into ash at the temperature of 500-600 ℃, and SiO in the main component293-98% of SiO2The method has important influence on the geological polymerization process, determines the structure of gel, and further influences the mechanical strength and durability; the cedar chips are calcined into ash at 500-550 ℃, the cedar chips are not sufficiently combusted due to the lower ashing temperature, the ash contains a certain amount of combustible components, namely activated carbon, the main components of the ash comprise 20-30% of CaO and SO 3The content of the cedar ash is 40-45%, and the cedar ash can provide sulfate ions for subsequent gelation of geopolymer and also can play a role in adsorption.
3) The invention mixes the curing agent mixture and the heavy metal polluted soil with water to ensure that the water content is 25-30 percent, and the heavy metal ions are cured by mainly utilizing the chemical and physical actions under the condition. Fe2O3、Al2O3And SiO2Is the main active substance in the slag, and the main component of the desulfurized gypsum is CaSO4·2H2O, the hydration product of both compounds contains a large amount of ettringite (3 CaO. Al)2O3·3CaSO4·32H2O); simultaneously under the action of an exciting agent, the silica glass bodyThe structure is further disintegrated in the alkaline environment provided by the phoenix tree leaf ash, and Al in the vitreous body2O3And SiO2With Ca in solution2+、SO4 2-And Al3+The equal hydration reaction generates a large amount of needle-shaped ettringite and partial C-S-H gel, and the cedar ash provides a large amount of SO4 2-While the amorphous silica of rice hull ash increases the Si/Al molar ratio of the geopolymer, reacts with hydroxyl to form silicate gel, and can obviously improve the performance of the geopolymer.
4) The heavy metal polluted soil curing agent benefits from a compact space formed by hydration products and the adsorption effect of activated carbon in the cedar ash, so that heavy metal ions form double physical packages, and meanwhile, hydroxide ions and the heavy metal ions generate chemical precipitation, the aim of curing the heavy metal ions is fulfilled, and leaching and migration are prevented.
5) The invention creatively uses a plurality of biomass ashes and reveals an internal relation between preparation conditions, physical properties and chemical properties; the method establishes a directional regulation and control method of the heavy metal polluted soil curing agent, develops a novel curing agent for curing heavy metal ion polluted soil, and cures the heavy metal polluted soil from a plurality of angles of adsorption action, physical action and chemical action.
Detailed Description
Preferred embodiments of the present invention will be described in more detail below. While the following describes preferred embodiments of the present invention, it should be understood that the present invention may be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
The preparation method of the heavy metal contaminated soil curing agent provided by the invention comprises the following steps:
1) drying and crushing the phoenix tree leaves, the rice hulls and the Chinese fir respectively to obtain corresponding biological chips (namely the phoenix tree leaf chips, the rice hull chips and the Chinese fir chips);
2) respectively putting the three biological crumbs into a muffle furnace to be burned at a proper temperature to obtain biomass ash;
3) Drying and uniformly mixing the slag powder and the desulfurized gypsum to obtain a dry mixture;
4) uniformly mixing the burned biomass ash with the dry mixture to prepare a heavy metal polluted soil curing agent;
the content of each component in the prepared heavy metal contaminated soil curing agent in the step 3) and the step 4) is as follows by mass percent: 60-88% of slag powder, 9-34% of desulfurized gypsum, 3-12% of biomass ash (i.e. an excitant), 1-4% of phoenix tree leaf ash, 1-4% of rice hull ash and 1-4% of cedar ash.
In step 1) of the present invention, the apparatus used for the pulverization is preferably a ball mill.
In the step 2), the firing temperatures of the phoenix tree leaf scraps, the rice hull scraps and the Chinese fir sawdust in the muffle furnace are 700-820 ℃, 500-600 ℃ and 500-550 ℃ respectively.
In the step 4), the drying temperature is 100-110 ℃.
The invention provides a method for solidifying heavy metal in heavy metal polluted soil by using a heavy metal polluted soil solidifying agent, which comprises the following steps:
1) and uniformly mixing the heavy metal contaminated soil curing agent and the heavy metal contaminated soil at normal temperature to obtain a mixture, wherein the mass ratios of the heavy metal contaminated soil and the heavy metal contaminated soil curing agent are respectively as follows: 70% -90% and 10% -30%;
2) Adding water into the mixture for mixing to enable the mixture to reach a water content of 25-30%;
3) and (3) stirring, compacting and molding the mixture after adding water to obtain a solidified block, and curing for 7-28 days under standard curing conditions of { (20 +/-2) ° C and humidity of 95% }.
In the invention, the heavy metal in the heavy metal contaminated soil at least comprises any one of copper, cadmium, chromium or lead ions.
The invention is further illustrated by the following examples:
example 1
The heavy metal contaminated soil curing agent adopted in the embodiment comprises the following raw materials in percentage by mass: 88% of slag, 9% of desulfurized gypsum, 1% of phoenix tree leaf ash, 1% of rice hull ash and 1% of cedar ash.
1) Putting the phoenix tree leaves, the rice hulls and the fir trees into a forced air drying oven, setting the temperature to be 105 ℃, drying to constant weight, taking out the phoenix tree leaves, the rice hulls and the fir trees, and crushing the dried phoenix tree leaves, the rice hulls and the fir trees respectively by using a ball mill until the phoenix tree leaves, the rice hulls and the fir trees are tiny granules to obtain processed biological chips;
2) respectively putting the processed biological chips into muffle furnaces, burning the phoenix tree leaf chips at 800 ℃, the rice hull chips at 550 ℃ and the cedar chips at 500 ℃ to obtain burned biomass ash;
3) drying the slag powder and the desulfurized gypsum in a 105 ℃ blast drying oven to constant weight, and uniformly mixing the slag powder and the desulfurized gypsum according to the corresponding mass percentage as required to obtain a dried mixture;
4) And uniformly mixing the treated curing agent raw materials in an UJZ-15 stirrer according to the mass percentage requirement to obtain the heavy metal contaminated soil curing agent, and sealing and storing.
Then, the heavy metal contaminated soil curing agent is used for curing the heavy metal in the heavy metal contaminated soil provided by the embodiment, and the method comprises the following steps:
1) uniformly mixing the heavy metal contaminated soil curing agent and the heavy metal contaminated soil at normal temperature to obtain a mixture, wherein the mass ratios of the heavy metal contaminated soil and the heavy metal contaminated soil curing agent are as follows: 70% and 30%;
2) adding water into the mixture prepared in the step 1) for mixing to ensure that the mixture has the water content of 30%;
3) and (2) uniformly stirring the mixture after adding water in an UJZ-15 stirrer, compacting and forming to obtain a solidified block, putting the solidified block into a standard curing box, and curing for 7 days under standard curing conditions of (20 +/-2) DEG C and humidity of 95 percent.
Example 2
The difference between the embodiment and the embodiment 1 is that the raw materials of the heavy metal contaminated soil curing agent comprise, by mass, 80% of slag, 15% of desulfurized gypsum, 2% of phoenix tree leaf ash, 1% of rice hull ash and 2% of cedar ash; the other process steps and process parameters were the same as in example 1.
Example 3
The difference between the embodiment and the embodiment 1 is that the raw materials of the heavy metal contaminated soil curing agent comprise 71% of slag, 21% of desulfurized gypsum, 2% of phoenix tree leaf ash, 3% of rice hull ash and 3% of cedar ash; the other process steps and process parameters were the same as in example 1.
Example 4
The difference between the embodiment and the embodiment 1 is that the raw materials of the heavy metal contaminated soil curing agent comprise 66% of slag, 26% of desulfurized gypsum, 4% of phoenix tree leaf ash, 2% of rice hull ash and 2% of cedar ash; the other process steps and process parameters were the same as in example 1.
Example 5
The heavy metal contaminated soil curing agent adopted in the embodiment comprises the following raw materials in percentage by mass: 86% of slag, 11% of desulfurized gypsum, 1% of phoenix tree leaf ash, 1% of rice hull ash and 1% of cedar ash.
1) Placing the phoenix tree leaves, the rice hulls and the fir trees into a forced air drying oven, setting the temperature to be 105 ℃, drying to constant weight, taking out the phoenix tree leaves, the rice hulls and the fir trees, crushing the dried phoenix tree leaves, the rice hulls and the fir trees by using a ball mill until the phoenix tree leaves, the rice hulls and the fir trees are tiny particles, and obtaining processed biological chips;
2) Respectively putting the processed biological chips into muffle furnaces, burning the phoenix tree leaf chips at 800 ℃, the rice hull chips at 550 ℃ and the cedar chips at 500 ℃ to obtain burned biomass ash;
3) drying the slag powder and the desulfurized gypsum in a 105 ℃ blast drying oven to constant weight, and uniformly mixing the slag powder and the desulfurized gypsum according to the corresponding mass percentage as required to obtain a dried mixture;
4) and uniformly mixing the treated curing agent raw materials in an UJZ-15 stirrer according to the mass percentage requirement to obtain the heavy metal contaminated soil curing agent, and sealing and storing.
Then, the heavy metal contaminated soil curing agent is used for curing the heavy metal in the heavy metal contaminated soil provided by the embodiment, and the method comprises the following steps:
1) uniformly mixing the heavy metal contaminated soil curing agent and the heavy metal contaminated soil at normal temperature to obtain a mixture, wherein the mass ratios of the heavy metal contaminated soil and the heavy metal contaminated soil curing agent are as follows: 80% and 20%;
2) adding water into the mixture prepared in the step 1) for mixing to ensure that the mixture has the water content of 30%;
3) and (3) uniformly stirring the mixture after the water is added into an UJZ-15 stirrer, compacting and forming to obtain a solidified block, putting the solidified block into a standard curing box, and curing for 7 days under standard curing conditions of (20 +/-2) DEG C and humidity of 95% }.
Example 6
The difference between the embodiment and the embodiment 2 is the mass ratio of the heavy metal contaminated soil and the heavy metal contaminated soil curing agent, and the mass ratio of the heavy metal contaminated soil and the heavy metal contaminated soil curing agent in the embodiment is as follows: 80% and 20%; in addition, the raw materials of the heavy metal contaminated soil curing agent in the embodiment comprise, by mass, 78% of slag, 17% of desulfurized gypsum, 2% of phoenix tree leaf ash, 1% of rice hull ash and 2% of cedar ash; the other steps, parameters and raw material addition were the same as in example 2.
Example 7
The difference between the embodiment and the embodiment 3 is that the mass ratio of the heavy metal contaminated soil to the heavy metal contaminated soil curing agent is as follows: 80% and 20%; in addition, the raw materials of the heavy metal contaminated soil curing agent in the embodiment comprise, by mass, 72% of slag, 22% of desulfurized gypsum, 1% of phoenix tree leaf ash, 3% of rice hull ash and 2% of cedar ash; the other steps, process parameters and raw material addition were the same as in example 3.
Example 8
The difference between the embodiment and the embodiment 4 is that the mass ratios of the heavy metal contaminated soil and the heavy metal contaminated soil curing agent are respectively as follows: 80% and 20%; in addition, the raw materials of the heavy metal contaminated soil curing agent in the embodiment comprise, by mass, 68% of slag, 26% of desulfurized gypsum, 3% of phoenix tree leaf ash, 1% of rice hull ash and 2% of cedar ash; the other steps, parameters and raw material addition were the same as in example 4.
Example 9
The heavy metal contaminated soil curing agent adopted in the embodiment comprises the following raw materials in percentage by mass: 88% of slag, 9% of desulfurized gypsum, 1% of phoenix tree leaf ash, 1% of rice hull ash and 1% of cedar ash.
1) Putting the phoenix tree leaves, the rice hulls and the fir trees into a forced air drying oven, setting the temperature to be 105 ℃, drying to constant weight, taking out the phoenix tree leaves, the rice hulls and the fir trees, crushing the dried phoenix tree leaves, the rice hulls and the fir trees by using a ball mill until the phoenix tree leaves, the rice hulls and the fir trees are tiny particles, and obtaining processed biological chips;
2) respectively putting the processed biological chips into muffle furnaces, burning the phoenix tree leaf chips at 800 ℃, the rice hull chips at 550 ℃ and the cedar chips at 500 ℃ to obtain burned biomass ash;
3) drying the slag powder and the desulfurized gypsum in a 105 ℃ blast drying oven to constant weight, and uniformly mixing the slag powder and the desulfurized gypsum according to the corresponding mass percentage as required to obtain a dried mixture;
4) and uniformly mixing the treated curing agent raw materials in an UJZ-15 stirrer according to the mass percentage requirement to obtain the heavy metal contaminated soil curing agent, and sealing and storing.
Then, the heavy metal in the heavy metal contaminated soil provided by the embodiment is solidified by adopting the heavy metal contaminated soil solidifying agent, and the method comprises the following steps:
1) Uniformly mixing the heavy metal contaminated soil curing agent and the heavy metal contaminated soil at normal temperature to obtain a mixture, wherein the mass ratios of the heavy metal contaminated soil and the heavy metal contaminated soil curing agent are as follows: 90% and 10%;
2) adding water into the mixture prepared in the step 1) for mixing to ensure that the mixture has the water content of 30%;
3) and (2) uniformly stirring the mixture after adding water in an UJZ-15 stirrer, compacting and forming to obtain a solidified block, putting the solidified block into a standard curing box, and curing for 7 days under standard curing conditions of (20 +/-2) DEG C and humidity of 95 percent.
Example 10
The difference between the embodiment and the embodiment 2 is the mass ratio of the heavy metal contaminated soil and the heavy metal contaminated soil curing agent, and the mass ratio of the heavy metal contaminated soil and the heavy metal contaminated soil curing agent in the embodiment is as follows: 90% and 10%; the other steps, parameters and raw material addition were the same as in example 2.
Example 11
The difference between the embodiment and the embodiment 3 is that the mass ratios of the heavy metal contaminated soil and the heavy metal contaminated soil curing agent are respectively as follows: 90% and 10%; the other steps, process parameters and raw material addition were the same as in example 3.
Example 12
The difference between the embodiment and the embodiment 4 is the mass ratio of the heavy metal contaminated soil and the heavy metal contaminated soil curing agent, and the mass ratio of the heavy metal contaminated soil and the heavy metal contaminated soil curing agent in the embodiment is as follows: 90% and 10%; the other steps, parameters and raw material addition were the same as in example 4.
Comparative example 1
The heavy metal contaminated soil curing agent adopted in the comparative example comprises the following raw materials in percentage by mass: 88% of slag, 9% of desulfurized gypsum, 1% of phoenix tree leaf ash, 1% of rice hull ash and 1% of cedar ash.
1) Placing the phoenix tree leaves, the rice hulls and the fir trees into a forced air drying oven, setting the temperature to be 105 ℃, drying to constant weight, taking out the phoenix tree leaves, the rice hulls and the fir trees, crushing the dried phoenix tree leaves, the rice hulls and the fir trees by using a ball mill until the phoenix tree leaves, the rice hulls and the fir trees are tiny particles, and obtaining processed biological chips;
2) respectively putting the processed biological chips into muffle furnaces, burning the phoenix tree leaf chips at 600 ℃, the rice hull chips at 400 ℃ and the Chinese fir chips at 500 ℃ to obtain burned biomass ash;
3) drying the slag powder and the desulfurized gypsum in a 105 ℃ blast drying oven to constant weight, and uniformly mixing the slag powder and the desulfurized gypsum according to the corresponding mass percentage as required to obtain a dried mixture;
4) And uniformly mixing the treated curing agent raw materials in an UJZ-15 stirrer according to the mass percentage requirement to obtain the heavy metal contaminated soil curing agent, and sealing and storing.
Then the heavy metal in the heavy metal pollutants provided by the comparative example is solidified by adopting the heavy metal polluted soil solidifying agent, and the method comprises the following steps:
1) uniformly mixing the heavy metal contaminated soil curing agent and the heavy metal contaminated soil at normal temperature to obtain a mixture, wherein the mass ratios of the heavy metal contaminated soil and the heavy metal contaminated soil curing agent are as follows: 70% and 30%;
2) adding water into the mixture prepared in the step 1) for mixing to ensure that the mixture has the water content of 30%;
3) and (2) uniformly stirring the mixture after adding water in an UJZ-15 stirrer, compacting and forming to obtain a solidified block, putting the solidified block into a standard curing box, and curing for 7 days under standard curing conditions of (20 +/-2) DEG C and humidity of 95 percent.
Comparative example 2A
The raw materials of the heavy metal polluted soil curing agent in the comparative example account for 80% of slag, 15% of desulfurized gypsum, 2% of phoenix tree leaf ash, 1% of rice hull ash and 2% of cedar ash by mass.
1) Placing the phoenix tree leaves, the rice hulls and the fir trees into a forced air drying oven, setting the temperature to be 105 ℃, drying to constant weight, taking out the phoenix tree leaves, the rice hulls and the fir trees, crushing the dried phoenix tree leaves, the rice hulls and the fir trees by using a ball mill until the phoenix tree leaves, the rice hulls and the fir trees are tiny particles, and obtaining processed biological chips;
2) Respectively putting the processed biological chips into muffle furnaces, burning the phoenix tree leaf chips at 550 ℃, rice hull chips at 550 ℃ and Chinese fir chips at 650 ℃ to obtain burned biomass ash;
3) drying the slag powder and the desulfurized gypsum in a 105 ℃ blast drying oven to constant weight, and uniformly mixing the slag powder and the desulfurized gypsum according to the corresponding mass percentage as required to obtain a dried mixture;
4) and uniformly mixing the treated curing agent raw materials in an UJZ-15 stirrer according to the mass percentage requirement to obtain the heavy metal contaminated soil curing agent, and sealing and storing.
Then the heavy metal in the heavy metal pollutants provided by the comparative example is solidified by adopting the heavy metal polluted soil solidifying agent, and the method comprises the following steps:
1) the heavy metal contaminated soil curing agent and the heavy metal contaminated soil are uniformly mixed at normal temperature to obtain a mixture, wherein the mass ratios of the heavy metal contaminated soil and the heavy metal contaminated soil curing agent are respectively as follows: 80% and 20%;
2) adding water into the mixture prepared in the step 1) and mixing to enable the mixture to reach the water content of 30%;
3) and (3) uniformly stirring the mixture after the water is added into an UJZ-15 stirrer, compacting and forming to obtain a solidified block, putting the solidified block into a standard curing box, and curing for 7 days under standard curing conditions of (20 +/-2) DEG C and humidity of 95% }.
Comparative example 2B
The comparative example 2B is different from the comparative example 2A only in the mass ratio of the heavy metal contaminated soil and the heavy metal contaminated soil curing agent, and in the comparative example, the mass ratio of the heavy metal contaminated soil and the heavy metal contaminated soil curing agent is respectively as follows: 70% and 30%.
Comparative example 3A
The raw materials of the heavy metal polluted soil curing agent in the comparative example comprise 71% of slag, 21% of desulfurized gypsum, 2% of phoenix tree leaf ash, 3% of rice hull ash and 3% of cedar ash by mass.
1) Putting the phoenix tree leaves, the rice hulls and the fir trees into a forced air drying oven, setting the temperature to be 105 ℃, drying to constant weight, taking out the phoenix tree leaves, the rice hulls and the fir trees, crushing the dried phoenix tree leaves, the rice hulls and the fir trees by using a ball mill until the phoenix tree leaves, the rice hulls and the fir trees are tiny particles, and obtaining processed biological chips;
2) respectively putting the processed biological chips into muffle furnaces, burning the phoenix tree leaf chips at 700 ℃, the rice hull chips at 450 ℃ and the Chinese fir chip at 600 ℃ to obtain burned biomass ash;
3) drying the slag powder and the desulfurized gypsum in a 105 ℃ blast drying oven to constant weight, and uniformly mixing the slag powder and the desulfurized gypsum according to the corresponding mass percentage as required to obtain a dried mixture;
4) and uniformly mixing the treated curing agent raw materials in an UJZ-15 stirrer according to the mass percentage requirement to obtain the heavy metal contaminated soil curing agent, and sealing and storing.
Then the heavy metal in the heavy metal pollutants provided by the comparative example is solidified by adopting the heavy metal polluted soil solidifying agent, and the method comprises the following steps:
1) uniformly mixing the heavy metal contaminated soil curing agent and the heavy metal contaminated soil at normal temperature to obtain a mixture, wherein the mass ratios of the heavy metal contaminated soil and the heavy metal contaminated soil curing agent are as follows: 90% and 10%;
2) adding water into the mixture prepared in the step 1) for mixing to ensure that the mixture has the water content of 30%;
3) and (3) uniformly stirring the mixture after the water is added into an UJZ-15 stirrer, compacting and forming to obtain a solidified block, putting the solidified block into a standard curing box, and curing for 7 days under standard curing conditions of (20 +/-2) DEG C and humidity of 95% }.
Comparative example 3B
The comparative example 3B is different from the comparative example 3A only in the mass ratios of the heavy metal contaminated soil and the heavy metal contaminated soil curing agent, and in the comparative example, the mass ratios of the heavy metal contaminated soil and the heavy metal contaminated soil curing agent are respectively as follows: 70% and 30%.
Comparative example 4
The mass percentage of the raw materials of the heavy metal polluted soil curing agent in the comparative example is 100 percent of slag.
1) Drying the slag powder in a 105 ℃ blast drying oven to constant weight, and taking the slag powder with corresponding mass according to requirements to obtain a dried mixture;
Then the heavy metal contaminated soil curing agent is used for curing the heavy metal in the heavy metal contaminated soil provided by the comparative example, and the method comprises the following steps:
1) uniformly mixing the heavy metal contaminated soil curing agent and the heavy metal contaminated soil at normal temperature to obtain a mixture, wherein the mass ratios of the heavy metal contaminated soil and the heavy metal contaminated soil curing agent are as follows: 70% and 30%;
2) adding water into the mixture prepared in the step 1) and mixing to enable the mixture to reach the water content of 30%;
3) and (3) uniformly stirring the mixture after the water is added into an UJZ-15 stirrer, compacting and forming to obtain a solidified block, putting the solidified block into a standard curing box, and curing for 7 days under standard curing conditions of (20 +/-2) DEG C and humidity of 95% }.
Comparative example 5A
The raw materials of the heavy metal polluted soil curing agent in the embodiment account for 76% of slag, 15% of desulfurized gypsum, 7% of phoenix tree leaf ash, 0% of rice hull ash and 2% of cedar ash by mass.
1) Placing folium Firmianae and lignum seu ramulus Cunninghamiae Lanceolatae in a forced air drying oven, setting temperature at 105 deg.C, drying to constant weight, taking out, and pulverizing with ball mill until the dried folium Firmianae and lignum seu ramulus Cunninghamiae Lanceolatae are micro-granular to obtain processed biological bits;
2) respectively putting the treated biological chips into a muffle furnace, and burning the phoenix tree leaf chips at 700 ℃ and the cedar wood chips at 500 ℃ to obtain burned biomass ash;
3) Drying the slag powder and the desulfurized gypsum in a 105 ℃ blast drying oven to constant weight, and uniformly mixing the slag powder and the desulfurized gypsum according to the corresponding mass percentage as required to obtain a dried mixture;
4) and uniformly mixing the treated curing agent raw materials in an UJZ-15 stirrer according to the mass percentage requirement to obtain the heavy metal contaminated soil curing agent, and sealing and storing.
Then the heavy metal contaminated soil curing agent is used for curing the heavy metal in the heavy metal contaminated soil provided by the comparative example, and the method comprises the following steps:
1) uniformly mixing the heavy metal contaminated soil curing agent and the heavy metal contaminated soil at normal temperature to obtain a mixture, wherein the mass ratios of the heavy metal contaminated soil and the heavy metal contaminated soil curing agent are as follows: 70% and 30%;
2) adding water into the mixture prepared in the step 1) for mixing to ensure that the mixture has the water content of 30%;
3) and (3) uniformly stirring the mixture after the water is added into an UJZ-15 stirrer, compacting and forming to obtain a solidified block, putting the solidified block into a standard curing box, and curing for 7 days under standard curing conditions of (20 +/-2) DEG C and humidity of 95% }.
Comparative example 5B
The difference from comparative example 5A is that in this comparative example:
the components in percentage by mass are 76% of slag, 15% of desulfurized gypsum, 0% of Chinese parasol tree leaf ash, 7% of rice hull ash and 2% of fir ash.
In the step 1), the rice hulls are treated into rice hull scraps, but the phoenix tree leaves are not treated into phoenix tree leaf scraps.
The step 2) does not have the treatment step of the phoenix tree leaf scraps, but has the step of burning the rice hull scraps at the temperature of 550 ℃ to obtain rice hull ash.
Comparative example 5C
The difference from comparative example 5A is that in this comparative example:
the components comprise 76% of slag, 15% of desulfurized gypsum, 2% of phoenix tree leaf ash, 7% of rice hull ash and 0% of cedar ash by mass.
In the step 1), the rice hulls are treated into rice hull scraps, but the fir wood is not treated into fir sawdust.
The step 2) does not comprise a processing step of the Chinese fir chips, but comprises a step of burning the rice hull chips at the temperature of 550 ℃ to obtain rice hull ash.
Comparative example 6
The raw materials of the heavy metal polluted soil curing agent in the embodiment comprise, by mass, 66% of slag, 26% of desulfurized gypsum, 4% of phoenix tree leaf ash, 2% of rice hull ash and 2% of cedar ash.
1) Placing the phoenix tree leaves and the fir wood into a forced air drying oven, setting the temperature to be 105 ℃, drying to constant weight, taking out the phoenix tree leaves and the fir wood, and crushing the dried phoenix tree leaves, the rice hulls and the fir wood by using a ball mill until the phoenix tree leaves, the rice hulls and the fir wood are tiny particles to obtain processed biological chips;
2) respectively putting the processed biological chips into a muffle furnace, and burning the phoenix tree leaf chips at 700 ℃, the rice hull chips at 900 ℃ and the cedar chips at 500 ℃ to obtain biomass ash;
3) Drying the slag powder and the desulfurized gypsum in a 105 ℃ blast drying oven to constant weight, and uniformly mixing the slag powder and the desulfurized gypsum according to the corresponding mass percentage as required to obtain a dry mixture;
4) and uniformly mixing the treated curing agent raw materials in an UJZ-15 stirrer according to the mass percentage requirement to obtain the heavy metal contaminated soil curing agent, and sealing and storing.
Then the heavy metal in the heavy metal contaminated soil provided by the comparative example is solidified by adopting the heavy metal contaminated soil solidifying agent, and the method comprises the following steps:
1) the heavy metal contaminated soil curing agent and the heavy metal contaminated soil are uniformly mixed at normal temperature to obtain a mixture, wherein the mass ratios of the heavy metal contaminated soil and the heavy metal contaminated soil curing agent are respectively as follows: 70% and 30%;
2) adding water into the mixture prepared in the step 1) and mixing to enable the mixture to reach the water content of 30%;
3) and (3) uniformly stirring the mixture after the water is added into an UJZ-15 stirrer, compacting and forming to obtain a solidified block, putting the solidified block into a standard curing box, and curing for 7 days under standard curing conditions of (20 +/-2) DEG C and humidity of 95% }.
In the above examples and comparative examples, the heavy metal contaminated soil is one of the same heavy metal contaminant, copper, cadmium, hexavalent chromium or lead. The leaching results before solidification and in examples 1 to 12 and comparative examples 1 to 6 were evaluated according to the national standard "hazardous waste discrimination standard-leaching toxicity discrimination" (GB5085.3-2007), and the toxicity leaching results are shown in Table 2 below.
TABLE 2 pollution toxicity leaching comparison table
As shown in Table 2, the heavy metal contaminated soil curing agent of the embodiment can reduce the leaching amount of heavy metals, and according to the requirements of national standard hazardous waste identification standard-leaching toxicity identification (GB5085.3-2007), the leaching concentration limit of copper is 100mg/L, the leaching concentration limit of cadmium is 1mg/L, the leaching concentration limit of hexavalent chromium is 5mg/L, and the leaching concentration limit of lead is 5 mg/L. The leaching concentration of the curing agent formula in the corresponding range in the examples and the comparative examples is far lower than the standard value.
Having described embodiments of the present invention and comparative examples, the foregoing description is illustrative, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.
Claims (4)
1. The preparation method of the heavy metal contaminated soil curing agent is characterized in that the curing agent comprises 60-88% by mass and 9-34% by mass of slag powder, desulfurized gypsum and an activator, wherein the activator is biomass ash obtained by treating Chinese parasol tree leaves, rice husks and Chinese fir and is 3-12% by mass;
The method comprises the following steps:
1) drying and crushing the phoenix tree leaves, the rice hulls and the Chinese fir respectively to obtain corresponding biological chips, namely the phoenix tree leaf chips, the rice hull chips and the Chinese fir chips;
2) respectively putting the three biological crumbs into a muffle furnace to be burned to obtain corresponding biomass ash, namely Chinese parasol tree leaf ash, rice hull ash and China fir ash; wherein, the phoenix tree leaf scraps are burned at the temperature of 700-820 ℃; firing the rice hull scraps at the temperature of 500-600 ℃; firing the cedar chips at the temperature of 500-550 ℃;
3) drying and uniformly mixing the slag powder and the desulfurized gypsum to obtain a dry mixture;
4) uniformly mixing the biomass ash obtained in the step 2) with the dry mixture obtained in the step 3) to obtain a heavy metal contaminated soil curing agent;
mixing the biomass ash obtained in the step 4) according to the mass ratio of (1-4) to obtain an exciting agent, wherein the exciting agent and the components obtained in the step 3) are contained in the prepared heavy metal polluted soil curing agent according to the mass percentage: 60-88% of slag powder, 9-34% of desulfurized gypsum and 3-12% of an excitant.
2. The method for preparing the curing agent according to claim 1, wherein the device used for the crushing in step 1) is a ball mill.
3. The method for preparing the curing agent according to claim 1 or 2, wherein the firing temperatures of the phoenix tree leaf chips, the rice hull chips and the cedar wood chips in the muffle furnace in the step 2) are 700 to 820 ℃, 500 to 600 ℃ and 500 to 550 ℃ respectively.
4. The method for preparing the curing agent according to claim 1 or 2, wherein the drying temperature in the step 3) is 100 to 110 ℃.
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