CN114409349B

CN114409349B - Salty mud curing material and preparation method and application thereof

Info

Publication number: CN114409349B
Application number: CN202111676008.6A
Authority: CN
Inventors: 张丽; 王志新
Original assignee: Beijing Junmei Environmental Technology Co ltd
Current assignee: Beijing Junmei Environmental Technology Co ltd
Priority date: 2021-12-31
Filing date: 2021-12-31
Publication date: 2023-02-24
Anticipated expiration: 2041-12-31
Also published as: CN114409349A

Abstract

The invention belongs to the field of salt mud curing, and particularly relates to a salt mud curing material as well as a preparation method and application thereof. The salt mud solidifying material provided by the invention is prepared from salt mud, solid particles, aluminum-containing mineral clinker and a water reducing agent. The invention can absorb a large amount of solid waste of the salty mud, skillfully utilizes the theory of the nascent state hydrotalcite to control the effective adsorption and fixation of chloride ions by combining the inherent components in the salty mud, controls the precipitation of the chloride ions and realizes the high strength and the high surface performance of the curing material; therefore, the invention is applied to the construction of salt pan slope protection and salt pan roads, and can meet the actual requirements of pressure resistance, sun resistance, impact resistance and the like on site.

Description

Salty mud curing material and preparation method and application thereof

Technical Field

The invention relates to the field of salt mud curing, in particular to a salt mud curing material and a preparation method and application thereof.

Background

Since the 50 s of the 20 th century, salt chemical industry has developed rapidly in our country, and salty mud as a by-product formed in salt industry belongs to solid waste. About 1 ton of salt mud is generated when 20 tons of raw salt are produced, and the yield of the salt mud in China is about 75 ten thousand tons in 2015. Currently, the annual production of salt mud worldwide has reached millions of tons. The salt mud contains a large amount of sodium chloride, calcium, magnesium and silicon components, and is dehydrated in a plate-and-frame filter pressing mode and the like, so that the water content is about 50%, and the utilization mode is not used temporarily. A large amount of salt mud waste residues are not treated and accumulated in a salt plant or directly transported to the suburb for accumulation, the high salt content and heavy metals in the salt mud waste residues cause serious pollution to soil, rivers, underground water and the like, and the treatment and disposal of the salt mud become an ecological environment problem to be solved urgently.

At present, the conventional disposal mode of the salt mud is to carry out filter pressing after secondary water washing, so that the content of sodium chloride in the treated salt mud is reduced, and the salt mud is subjected to landfill treatment after meeting the environmental protection requirement. The treatment method not only needs to spend a large amount of manpower, material resources and financial resources for the transportation and backfilling of the salt mud, increases the production cost of enterprises, but also is very easy to cause secondary pollution in the transportation and landfill processes, and does not carry out resource utilization.

The effective components in the salt slurry mainly comprise precipitated calcium carbonate, magnesium hydroxide, sodium chloride, silicon dioxide and the like, and the components can be utilized after treatment, so that the salt slurry has certain economic value. Common salt mud resource utilization modes include manufacturing of building materials (cement, artificial brick, tile, slate and the like), water treatment agents (adsorbents, conditioners and the like), additives (rubber and plastic products, drilling fluids and the like), fine chemicals, ceramsite, fertilizer, snow melting agents, desulfurizing agents and the like, but the method depends on secondary purification and equipment processing, and is high in energy consumption and cost. The salt mud waste is used for the construction of salt field revetments, so that the solid waste reduction and the comprehensive utilization can be organically combined, but the related research and engineering application is less. A plurality of technical schemes are provided for salt mud treatment at home and abroad, rich experience is accumulated, but large-scale popularization and application cannot be achieved due to the reasons of economy, technology and the like. Research and development of application technology which is suitable for salt mud treatment and can be popularized on a large scale are the technical problems which are faced by all domestic salt manufacturing enterprises.

The salt slurry is mainly used as an additive component in the recycling mode, such as fly ash brick making and cement making, and is also used for manufacturing ceramic particles, the salt slurry is added in a small amount according to a proportion, and the excessive addition can seriously affect the product quality, wherein the main reason is that the popularization and the use are influenced due to the existence of chloride ions;

the relevant specifications for concrete additive materials require that the chloride ion content in the cementitious material (including cement, fly ash, mineral powder, and additives) is not greater than 0.06% because chloride ions can reduce the strength of the concrete.

Chloride ions in concrete can be combined with calcium in the hydration process of the concrete to generate calcium chloride which is a powdery non-strength compound, the solidified concrete contains the calcium chloride without bonding strength, and the chloride ions can also damage the chemical corrosion resistance of the concrete, so that the strength of the concrete can be reduced to a great extent, the situation that local loosening and bearing capacity are insufficient in the whole building can be caused, the service life of the concrete in the building engineering can be reduced, and therefore, when the content of the chloride ions in the concrete is higher, the concrete can be in a low-strength and easily-corroded state, the concrete building structure is damaged, the concrete is stripped, the use condition of a building component can deviate from the original design standard, and the very direct negative influence effect on the structure of the whole building can be achieved.

The chloride ion content of the salt slurry is 10-20% and has serious influence on the hardness and durability of a solidified body, and particularly, when the chloride ion exists freely, the corrosion of the chloride ion to the solidified body is more serious.

The solid waste residue and little cement-based material are usually reinforced in the strength and coagulation property by using additives/curing agents in the curing process, the additives or curing agents are usually composed of organic surfactants or inorganic salt ions, the organic surfactants can be adsorbed on the surfaces of particles and hydrates to cause surface physical and chemical property changes such as electrification property, contact angle and the like, and anions in the inorganic salt ions are easy to form surface competitive adsorption with chloride ions, so that inevitable negative effects are generated on the adsorption of the chloride ions.

Further distinguishing and finding out that the influence of the factors on the chloride ion adsorption mainly influences the physical adsorption effect and has no obvious influence on the chemical binding effect, so that the solution idea still needs to form chemical binding as much as possible.

Tricalcium silicate (C3S) and dicalcium silicate (C2S) in the cement-based material adsorb chloride ions to the chloride ions through Van der Waals force, and the desorption of the chloride ions is easily caused by the influence of additives and additives.

CN202110750650.8 discloses a setting and solidifying material for setting and solidifying industrial high-salt organic waste liquid evaporated salt mud, a hardened body containing the setting and solidifying material and a preparation method thereof, wherein the setting and solidifying material consists of an inorganic solidifying agent, mineral solid waste and a composite additive, the inorganic solidifying agent comprises one or a combination of more than two of silicate (portland cement), iron aluminate (iron aluminate cement) and aluminate (aluminate cement), the mineral solid waste comprises one or a combination of more than two of stone powder, fly ash, broken stone, gangue, fly ash, steel slag, desulfurized gypsum and desulfurized alkaline residue, the composite additive comprises a high-fine inorganic material and an organic material comprising naphthalene active materials and/or cellulose, the mass ratio of the three materials is 1 (0.3-3): (0.005-0.1), the setting and solidifying material can efficiently adsorb harmful components in the high-salt organic waste liquid evaporated salt mud containing 100-300 g/L of salt, the harmful components in the high-salt organic waste liquid evaporated salt mud can be improved, the viscosity of the setting material can be increased, the compact body can be solidified, the bleeding phenomenon can be reduced, the solidification body can be easily prepared, and the solidification strength can be easily produced. The mass ratio of the inorganic curing agent to the mining solid waste to the composite admixture is 1 (0.3-3) to (0.005-0.1), the maximum ratio of the inorganic curing agent to the mining solid waste to the composite admixture in the patent is 1.

Disclosure of Invention

In view of the above, the technical problem to be solved by the present invention is to provide a cured material of salt slurry, a preparation method and an application thereof. In the salt mud curing material provided by the invention, the addition amount of the salt mud is high, and the strength and the surface performance of a cured body are good.

The invention provides a salty mud curing material which is prepared from the following raw materials:

50-95 parts of salt mud;

1-3 parts of solid particles with the particle size of less than 3 mm;

3-8 parts of aluminum-containing mineral clinker;

0.012 to 0.024 portion of water reducing agent.

The invention takes the salt mud as the main additive component, and takes the air-dried salt mud as the raw material, and the water content of the salt mud is less than 8 percent. In one embodiment, the salty mud is salty mud with high chloride ion content, and the chloride ion content is 10-20 wt%. In the invention, the amount of the salty mud is 50 to 95 parts. In one embodiment, the amount of the salty mud is 80 to 95 parts.

In one embodiment, the salt mud is a physical salt mud and/or a chemical salt mud, preferably a physical salt mud; in one embodiment, the physical salt mud refers to filter-pressing mud generated after crude salt in a salt field is directly physically dissolved and is subjected to filter pressing by a plate frame; siO of the physical salt mud ₂ The content is 1-5 wt%. In one embodiment, the chemical salt slurry refers to the slurry generated after chemical reagents such as electrolysis, precipitation dissolution and the like are added in the industrial production process of edible salt and chlor-alkali; siO of the chemical salt slurry ₂ The content is 0 to 1wt percent. SiO in physical salt mud relative to chemical salt mud ₂ The content is relatively high, which is beneficial to the formation of solidified salt mud.

The salt mud solidified material provided by the invention also comprises solid particles with the particle size of less than 3 mm. The solid particles are selected from one or more of construction waste, crushed stone chips, coal gangue, sandstone, steel slag, slag and slag byproducts. In one embodiment, the solid particles are sand. The solid particles with the particle size of less than 3mm are matched with the salt slurry for use, so that the obtained solidified material has higher strength, for example, the strength of more than 15MPa is achieved. In one embodiment, the solid particles are used in an amount of 1 to 3 parts.

The salty mud solidifying material provided by the invention also comprises aluminum-containing mineral clinker which can react with magnesium, calcium and the like in salty mud to generate Mg-Al and Ca-Al hydrotalcite, and the hydrotalcite can effectively adsorb free chloride ions in a system, so that the negative effects of corrosion, strength influence and the like of the free chloride ions on a solidified body are reduced. In one embodiment, the addition amount of the aluminum-containing mineral clinker is 3 to 8 parts. In one embodiment, the aluminous mineral clinker comprises aluminate cement, sulphoaluminate cement, ferro-aluminate cement.

The salt mud solidifying material provided by the invention also comprises a water reducing agent. The water reducing agent is selected from one or more of lignosulfonate water reducing agents, naphthalene water reducing agents, melamine water reducing agents, sulfamate water reducing agents, fatty acid water reducing agents and polycarboxylate water reducing agents. The water reducing agent is a surfactant, can play a role of a dispersing agent, can reduce the using amount of cement in a curing project, and can enable a cured body to achieve higher strength. In the invention, the addition amount of the water reducing agent is 0.012-0.024 parts, which is 0.15-0.8% of the dosage of the aluminum-containing mineral clinker. In one embodiment, the water reducing agent is added in an amount of 0.02 parts.

The invention provides a salty mud curing material which is prepared from the components.

The invention provides a preparation method of a salt mud solidified material, which comprises the following steps:

mixing the salt slurry, the solid particles, the aluminum-containing mineral clinker, the water reducer and water, reacting and curing to obtain the salt slurry curing material.

The addition amounts of the salt mud, the solid particles, the aluminum-containing mineral clinker and the water reducer are the same as those described above, and are not described again here.

The method comprises the steps of mixing the salt slurry, the solid particles, the aluminum-containing mineral clinker, the water reducing agent and water to obtain a mixture of the salt slurry, the solid particles, the aluminum-containing mineral clinker, the water reducing agent and the water.

Specifically, the order of mixing is not particularly limited, and may be arbitrarily adjusted according to the actual situation; for example, the water reducing agent can be diluted by water and then added into the salt slurry, the solid particles and the aluminum-containing mineral clinker to be mixed; in one embodiment, the dilution factor is 15 to 50. In one embodiment, the dilution factor is 15 to 30.

During mixing, stirring can be carried out, so that the components are uniformly mixed and the full reaction is promoted.

After being stirred evenly, the salt mud curing material can be obtained after reaction and curing. In one embodiment, the reaction aging time is 2 hours or more.

The mixture of the salt mud, the solid particles, the aluminum-containing mineral clinker, the water reducing agent and the water can also be added with a pH regulator to regulate the pH value to 8-10, regulate the proper alkaline range and control the generation of the magnesium aluminum-calcium aluminum hydrotalcite to the maximum extent. In one embodiment, the addition amount of the pH adjuster is 0.5 to 2 parts. The pH regulator is borate and/or phosphate. In one embodiment, the borate is sodium borate and/or boric acid; in one embodiment, the phosphate is one or more of diammonium phosphate, monoammonium phosphate, calcium hydrogen phosphate, calcium pyrophosphate, monopotassium phosphate, dipotassium phosphate, sodium acid pyrophosphate, sodium dihydrogen phosphate, disodium hydrogen phosphate, sodium pyrophosphate, and sodium aluminum phosphate.

After the salt mud curing material is obtained, the salt mud curing material can be pressed into different forms by applying mechanical loading force according to different requirements.

For example, the invention provides a baking-free brick, which is obtained by pressing and molding the salt mud solidified material; the invention also provides concrete which is prepared from the salt mud curing material; the baking-free brick and the concrete are naturally cured into a solidified body without baking and steaming, can greatly reduce energy consumption and carbon dioxide emission, and the solidified body has excellent compressive strength, impact resistance, soaking resistance and the like, and can be used for building materials or road paving to treat a large amount of salt mud.

The salty mud solidifying material provided by the invention is prepared from 50-95 parts of salty mud, 1-3 parts of solid particles with the particle size of less than 3mm, 3-8 parts of aluminum-containing mineral clinker and 0.012-0.024 part of water reducing agent. The invention takes the aluminum-containing mineral clinker as the coagulating material to react with the salty mud, can generate hydrotalcite to adsorb chloride ions, and can solve the influence of the chloride ions on the corrosion and the strength of a solidified body, thereby leading the salty mud addition amount of the salty mud solidified material to be high, leading the proportion of the added components to be lower than 10wt%, being capable of maximally treating and absorbing the salty mud, particularly the salty mud with high chloride ion content, under the condition of least added components, and realizing the harmless and resource recycling of the salty mud with high chloride ion content. Meanwhile, the salt mud curing material provided by the invention can quickly realize better strength and surface property of a cured body without adding substances such as an early strength agent and the like, can reach the compressive strength of more than 15MPa, has good surface property, does not have serious salting-out phenomenon apparently after being washed by rainwater, and has no obvious collapse and holes on the surface.

Detailed Description

The invention discloses a salty mud curing material and a preparation method and application thereof. Those skilled in the art can modify the process parameters appropriately in view of the disclosure herein. It is expressly intended that all such similar substitutes and modifications which would be obvious to one skilled in the art are deemed to be included in the invention. While the methods and applications of this invention have been described in terms of preferred embodiments, it will be apparent to those of ordinary skill in the art that variations and modifications in the methods and applications described herein, as well as other suitable variations and combinations, may be made to implement and use the techniques of this invention without departing from the spirit and scope of the invention.

The invention is further illustrated by the following examples:

example 1

Aiming at the return field salt mud extracted from crude salt in a certain coastal salt field in North China, the water content is about 5 percent after air drying. Adopting 94 parts of the salt slurry, adding 3 parts of sandstone with the particle size smaller than 3mm and 5 parts of aluminate cement, stirring for 1min, and uniformly mixing to obtain a mixture; and (2) taking a sulfamate water reducing agent accounting for 0.02 percent of the total mass of the mixture, diluting the sulfamate water reducing agent by 30 times of water, adding the mixture into the mixture, uniformly stirring, performing common rolling forming, adding water every 12 hours for curing for 7 days, and obtaining a rectangular brick structure body with the length of 24cm, the width of 11.5cm and the height of 5.6 cm. Then carrying out unconfined compressive strength, continuous seawater soaking, compactness, ion leaching experiment and soaking resistance test.

Example 2

The difference from the embodiment 1 is that a 200-tonnage brick making machine is adopted for pressing and forming.

Comparative example 1

The difference from example 2 is that portland cement is used.

Example 3

Unconfined compressive strength, continuous seawater soaking and compactness experiment results:

for the brick of example 1, the 7-day unconfined compressive strength was 2.8MPa; for the block of example 2, the 7-day unconfined compressive strength was 18.2MPa and the 28-day strength reached 27MPa. The compactness of the bricks in the embodiments 1 and 2 is 95%, and after 7 days of continuous seawater immersion experiments, the surfaces of the bricks have no collapsed parts and are still smooth surfaces.

The result of the anti-soaking performance test is as follows:

the block made in example 2 was immersed in water for 30 consecutive days, with the ratio of the mass of the block to the volume of water being 1kg. The results show that the brick surface has no corrosion, collapse and holes, and the corners are relatively hard and have no collapse.

Ion leaching experiment results:

according to HJ 557-2010, the brick obtained in example 2 was crushed to a diameter of 3mm or less, a primary leaching experiment was performed at a liquid-solid ratio of 10 (L/kg) according to the water content of the sample, and a secondary leaching experiment was performed in the same manner after centrifugal separation of the solid component after the experiment. For comparison, the original salty mud was subjected to a leaching experiment in the manner described above. Table 1 shows the results of the ion leaching experiments.

Table 1 results of ion leaching experiments

As is apparent from Table 1, the brick obtained in example 2 showed a significantly lower leaching concentration of chloride ions than the original salt slurry and the brick obtained in comparative example 1, indicating that the precipitation of chloride ions was effectively controlled, and that the cured product obtained from portland cement was significantly inferior in chloride ion curing effect to the cured product obtained from aluminate cement.

Example 4

Aiming at returning field salt mud extracted from crude salt in a certain coastal salt field in North China, aluminate cement accounting for 8wt% of the salt mud is added into the salt mud, and 0.02wt% of sulfamate water reducing agent is added to lay road surfaces in a salt field production area. The width of the paved road is 3 meters, the length of the paved road is 1 kilometer, the designed speed is 40km/h, the vehicle with the pressure bearing capacity of less than or equal to 50 tons passes in two directions, and the service life is more than or equal to 5 years.

The specific method comprises the following steps: leveling a base layer of a solidified soil layer before construction to ensure that the base layer is flat and solid, and adding aluminate cement accounting for 8wt% of salt mud into the salt mud in a centralized mixing mode to obtain a mixture; and (3) diluting the sulfamate water reducer which accounts for 0.02wt% of the total mass of the mixture by 20 times with water, adding the sulfamate water reducer into the mixture, and uniformly stirring to obtain the salt mud curing material. And paving the salt mud curing material into a road according to a design elevation in a mode of matching equipment with manual work, and finely leveling and calendaring the surface of the road by adopting a small-sized double-steel-wheel road roller.

The heavy-load disturbance is forbidden in 7 days of the road paving area, the road surface is watered and maintained every day, the compressive strength is tested according to the current industry standard 'technical specification for constructing the base course of the road surface' of the traffic department after 7 days, a drilling core column taking test method is adopted, the total number of samples is 4, the compressive strengths are respectively 2.5, 4.3, 3.0 and 4.1MPa, then the samples can be used, and after 28 days, all point position strength values are more than 3.0MPa. Table 2 shows the point location strength value test results.

Table 2: point location strength value test result

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims

1. A salty mud solidified material is prepared from the following raw materials:

80 to 95 parts of salt slurry;

1 to 3 parts of solid particles with the particle size of less than 3mm, wherein the solid particles are selected from one or more of construction waste and sand;

3 to 8 parts of an aluminum-containing mineral clinker selected from sulphoaluminate cement;

0.012 to 0.024 parts of a water reducing agent; the water reducing agent is a sulfamate water reducing agent.

2. The cured salt mud material of claim 1, wherein the Cl ion content of the salt mud is 10 to 20wt%.

3. The method for preparing the salty mud solidified material according to claim 1 or 2, which comprises the following steps:

4. The preparation method according to claim 3, wherein the pH value of the mixture of the salty mud, the solid particles, the aluminum-containing mineral clinker, the water reducing agent and the water is 8 to 10.

5. A baking-free brick, which is obtained by pressing and molding the salt mud curing material of any one of claims 1-2.

6. A concrete obtained from the cured salt slurry material according to any one of claims 1 to 2.