Method for preparing cast stone by using acid washing sludge and solid waste in coordination

Abstract

The application utilizes pickling sludge to prepare cast stone in cooperation with solid waste, and comprises the following steps: pickling sludge and auxiliary materials are proportioned at 75:25-92:8, the water content is less than 8%, the mixture is mixed after proportioning, the mixed material is made into mixed material spheres with a diameter of 8-15 cm, the mixed material spheres are put into a countercurrent drying furnace for drying and sintering, the dried spheres are transported to a melting furnace by a chain plate machine for melting, sampling and component detection are performed every 1-2 hours during the transportation, trace adjustment is performed according to the sampling result, the addition ratio is 1-10% of the mixed material spheres, the acidity value is 1.1-2.0, the molten liquid magma is put into a preheated mold, moved to a heat treatment furnace for heat preservation for 1 hour, annealed for 1 hour, and finally cooled to room temperature with the furnace to obtain cast stone. The cast stone realizes large-scale resource utilization of industrial waste, prevents secondary environmental pollution, and has good social and economic benefits.

Description

Technical Field

[0001] This invention belongs to the field of stone material technology, specifically relating to a method for preparing cast stone using acid-washed sludge in conjunction with solid waste. Background Technology

[0002] According to the National Hazardous Waste List (2016 Edition), HW46 nickel-containing waste originates from industries such as basic chemical raw material manufacturing and battery manufacturing. It mainly includes reaction residues, substandard products, obsolete waste, and slag generated during the production of nickel compounds. It also includes wastewater treatment sludge and waste nickel catalysts generated during the production of nickel-metal hydride batteries.

[0003] Nickel-containing waste poses a significant threat to human health and the ecological environment. Nickel compounds, especially nickel carbonyl, are classified as carcinogens. Acute poisoning can occur through the absorption of nickel alkalis, leading to symptoms such as nausea, vomiting, high fever, difficulty breathing, and chest pain. Exposure to high concentrations can cause acute chemical pneumonia, ultimately resulting in pulmonary edema and respiratory and circulatory failure, leading to death. Base nickel also enters the atmosphere, water, and soil, negatively impacting the growth of organisms. As a heavy metal, nickel cannot be eliminated through the self-purification of water and soil. It ultimately enters the human body through the food chain, accumulating and harming human health.

[0004] HW17 includes hazardous waste generated from metal surface treatment and heat treatment processes, mainly waste residue and wastewater treatment sludge generated from sensitization using stannous chloride, waste residue and wastewater treatment sludge generated from sensitization using zinc chloride and ammonium chloride, and plating bath solutions, plating slag, and wastewater treatment sludge generated from zinc plating using zinc and electroplating chemicals.

[0005] Surface treatment waste contains large amounts of toxic heavy metals and corrosive waste liquids, such as chromium, cadmium, and nickel. Improper handling will cause serious and long-term secondary pollution to human health and the ecological environment. Heavy metals are non-biodegradable and persist in nature for extended periods, accumulating in the human body through the food chain and causing heavy metal poisoning and other health problems. Corrosive waste liquids not only pollute water bodies and soil, reducing the environmental function of the area, but also have a strong irritant and corrosive effect on skin, mucous membranes, and other tissues, seriously affecting human health.

[0006] my country also generates a large amount of industrial solid waste every year, seriously threatening human health and the living environment. Accumulated solid waste, after being soaked by rainwater and undergoing decomposition, will cause pollution to nearby rivers, groundwater systems, and resources through the transformation and migration of leachate and harmful chemicals. Tailings, fly ash, dried sludge, and dust from garbage in solid waste will be carried by the wind, polluting the atmosphere. Many solid wastes themselves, or during incineration, release toxic gases and foul odors, harming human health.

[0007] Therefore, it is urgent to develop a technology that can solve the environmental hazards of pickling sludge and industrial solid waste while making large-scale resource utilization, which has good social and economic benefits. Summary of the Invention

[0008] The technical problem to be solved by this invention is to provide a method for preparing cast stone by using pickling sludge and solid waste in combination, in order to address the various defects and deficiencies of the existing technology. The technical problem to be solved is to safely solidify pickling sludge and industrial solid waste, while improving the utilization rate of waste, and applying them to the production of cast stone.

[0009] The specific technical solution of this invention is as follows:

[0010] A method for preparing cast stone using acid washing sludge and solid waste includes the following steps:

[0011] (1) Mix the pickling sludge and auxiliary materials in a ratio of 75:25 to 92:8. Dilute the pickling sludge with water to a moisture content of less than 8%. After mixing, use a mixer to mix the pickling sludge and solid waste evenly.

[0012] (2) Place the well-mixed mixture into a pelletizing pan and form pellets. Under the action of the adhesive, pellets with a diameter of 8 to 15 cm are formed.

[0013] (3) The mixed pellets are placed in a countercurrent drying oven for drying and sintering at a temperature of 800-1000℃. After drying, they are conveyed to a melting furnace by a chain conveyor. Due to the instability of the composition of the pickling sludge, samples are taken every 1-2 hours during the conveying process to test the composition. Based on the sampling results, the sintered mixed pellets are slightly adjusted from the siliceous material silo or calcareous material silo through the conveying pipeline. The addition ratio is 1-10% of the mixed pellets to make its acidity value 1.1-2.0.

[0014] (4) The molten liquid magma is placed into a preheated mold, and the mold is transferred to a heat treatment furnace and kept at 900°C for 1 hour. The temperature is then lowered to 650°C and kept at 650°C for 1 hour for annealing. Finally, the magma is cooled to room temperature with the furnace to obtain cast stone.

[0015] Preferably, the auxiliary materials include one of the following: carbide slag, waste gypsum or crystal slag and limestone, with a specific ratio of pickling sludge: waste gypsum of 85:15 to 92:8, pickling sludge: carbide slag of 80:20 to 90:10, or pickling sludge: crystal slag: limestone of 75:20:5 to 80:16:4.

[0016] Preferably, the melting furnace is a natural gas melting furnace with a melting temperature of 1400–1480℃. Below 1400℃, bubbles are prone to appear; the temperature is generally controlled between 1400–1450℃, although bubbles may occasionally occur. While the production cost is higher at 1460–1480℃, bubbles are virtually eliminated. The melting time is 30–35 minutes. The mold preheating temperature is 850–900℃. Mold preheating prevents the liquid magma from contacting the room-temperature mold surface, which would cause the cast stone surface to cool too quickly and crack. Combined with heat treatment and insulation, the surface structure of the cast stone is stabilized. Because the cast stone blocks are large, with a maximum size of 60cm x 120cm x 30cm, annealing is also required to eliminate stress from the center and surface temperatures, preventing overall cracking. The stones can be cut into appropriate sizes according to actual needs.

[0017] Preferably, quartz sand or slag is placed in the siliceous material silo, and limestone is placed in the calcareous material silo.

[0018] Preferably, both the chain conveyor and the conveyor pipe have weighing functions to ensure that minor adjustments are made before feeding into the melting furnace to meet the required acidity value.

[0019] Preferably, the pickling sludge includes the pickling sludge contained in HW46 or the surface treatment material of HW17.

[0020] The present invention, by adopting the above technical solution, has the following advantages:

[0021] 1. The cast stone of this invention has a slightly higher strength than natural stone. It can be cut into the required size and can be widely used in various industries to improve waste utilization and realize the large-scale resource utilization of industrial waste.

[0022] 2. The pickling sludge is melted at high temperature to solidify heavy metal ions and decompose dioxins, and the problem of high chloride content in fly ash is solved. It eliminates the need for landfill, saves land resources, and prevents further environmental pollution.

[0023] 3. This invention utilizes a large amount of industrial solid waste, reducing its pollution to the ecological environment, while giving it high added value, resulting in good social and economic benefits.

[0024] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below. Attached Figure Description

[0025] Figure 1 : This is the XRD test pattern of the present invention. Detailed Implementation

[0026] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following detailed description, in conjunction with preferred embodiments, details the specific implementation methods, structures, features, and effects of the method for preparing cast stone using acid-washed sludge in conjunction with solid waste, as proposed by the present invention. Furthermore, specific features, structures, or characteristics in one or more embodiments may be combined in any suitable form.

[0027] Example 1

[0028] A method for preparing cast stone using acid washing sludge and solid waste includes the following steps:

[0029] (1) The pickling sludge and waste gypsum were mixed in a ratio of 85:15. The pickling sludge was diluted with water to a moisture content of 7.8%. After mixing, the pickling sludge and solid waste were mixed evenly using a mixer.

[0030] (2) Place the well-mixed mixture into a pelletizing pan and form pellets. Under the action of the adhesive, the mixture pellets with a diameter of 15cm are formed.

[0031] (3) The mixed material pellets are placed in a countercurrent drying furnace for drying and sintering at a temperature of 1000℃. After drying, they are conveyed to a natural gas melting furnace via a chain conveyor for melting. Due to the instability of the composition of the pickling sludge, samples are taken every hour during the conveying process to test the composition. Based on the weighing results of the chain conveyor, quartz sand is taken out from the quartz sand bin or limestone is taken out from the limestone bin. The sintered mixed material pellets are then slightly adjusted according to the required proportion through the conveying pipeline. The addition ratio is 1-10% of the mixed material pellets, so that the acidity value is 1.1-2.0, the melting temperature is 1450℃, and the melting time is 35 minutes.

[0032] (4) The molten liquid magma is placed into a mold with a preheated temperature of 900°C, and the mold is transferred to a heat treatment furnace and kept at 900°C for 1 hour. The temperature is then lowered to 650°C and kept at 650°C for 1 hour for annealing. Finally, the magma is cooled to room temperature with the furnace to obtain cast stone.

[0033] Example 2

[0034] A method for preparing cast stone using acid washing sludge and solid waste includes the following steps:

[0035] (1) The pickling sludge and carbide slag are mixed in a ratio of 80:20. The pickling sludge is diluted with water to a moisture content of 7.6%. After mixing, the pickling sludge and solid waste are mixed evenly using a mixer.

[0036] (2) Place the well-mixed mixture into a pelletizing pan to form pellets, and form pellets with a diameter of 8cm under the action of the adhesive;

[0037] (3) The mixed material balls are placed in a countercurrent drying furnace for drying and sintering at a temperature of 900°C. After drying, they are conveyed to a natural gas melting furnace via a chain conveyor for melting. Due to the instability of the composition of the pickling sludge, samples are taken every 2 hours during the conveying process to test the composition. Based on the weighing results of the chain conveyor, quartz sand is taken out from the quartz sand bin or limestone is taken out from the limestone bin. The sintered mixed material balls are then slightly adjusted according to the required proportion through the conveying pipeline. The addition ratio is 1-10% of the mixed material balls, so that the acidity value is 1.1-2.0, the melting temperature is 1480°C, and the melting time is 30 minutes.

[0038] (4) The molten liquid magma is placed into a mold with a preheated temperature of 850°C, and the mold is transferred to a heat treatment furnace and kept at 900°C for 1 hour. The temperature is then lowered to 650°C and kept at 650°C for 1 hour for annealing. Finally, the magma is cooled to room temperature with the furnace to obtain cast stone.

[0039] Example 3

[0040] A method for preparing cast stone using acid washing sludge and solid waste includes the following steps:

[0041] (1) The pickling sludge, crystal slag and limestone are mixed in a ratio of 75:20:5. The pickling sludge is diluted with water to a moisture content of 7.2%. After mixing, the pickling sludge and solid waste are mixed evenly using a mixer.

[0042] (2) Place the well-mixed mixture into a pelletizing pan to form pellets, and form pellets with a diameter of 12cm under the action of the adhesive;

[0043] (3) The mixed material balls are placed in a countercurrent drying furnace for drying and sintering at a temperature of 800°C. After drying, they are conveyed to a natural gas melting furnace via a chain conveyor for melting. Due to the instability of the composition of the pickling sludge, samples are taken every 1.5 hours during the conveying process to test the composition. Based on the weighing results of the chain conveyor, quartz sand is taken out from the quartz sand bin or limestone is taken out from the limestone bin. The sintered mixed material balls are then slightly adjusted according to the required proportion through the conveying pipeline. The addition ratio is 1-10% of the mixed material balls, so that the acidity value is 1.1-2.0, the melting temperature is 1400°C, and the melting time is 30 minutes.

[0044] (4) The molten liquid magma was placed into a mold with a preheated temperature of 850°C. The mold was then transferred to a heat treatment furnace and kept at 900°C for 1 hour. The temperature was then lowered to 650°C and kept at 650°C for 1 hour for annealing. Finally, the magma was cooled to room temperature with the furnace to obtain cast stone. Some of the cast stone in this batch had air bubbles inside.

[0045] Partial test data: A small piece measuring 19.66 mm in length, 12.83 mm in width, and 4.99 mm in thickness was tested for bending strength using a ceramic bending strength tester. The bending strength reached 18.91 MPa, which is higher than the national stone standard of 8.3 MPa.

[0046] Samples were taken for XRD testing, as shown in the attached image. Figure 1 As shown, XRD results indicate that the main crystalline phases of the sample are spinel and fluorapatite. Spinel has strong heavy metal consolidation properties, therefore cast stone can serve as an excellent material for the resource utilization of solid waste.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing cast stone using acid-washed sludge and solid waste, characterized in that, Includes the following steps: (1) Mix the pickling sludge and solid waste according to the ratio, dilute the pickling sludge with water to a moisture content of less than 8%, and mix them with a mixer after mixing to make the pickling sludge and solid waste evenly mixed. (2) Place the well-mixed mixture into a pelletizing pan and form pellets. Under the action of the adhesive, pellets with a diameter of 8 to 15 cm are formed. (3) The mixed pellets are placed in a countercurrent drying oven for drying and sintering at a temperature of 800-1000℃. After drying, they are conveyed to a melting furnace by a chain conveyor. Due to the instability of the composition of the pickling sludge, samples are taken every 1-2 hours during the conveying process to test the composition. Based on the sampling results, the sintered mixed pellets are slightly adjusted from the siliceous material silo or calcareous material silo through the conveying pipeline. The addition ratio is 1-10% of the mixed pellets to make its acidity value 1.1-2.

0. (4) The molten liquid magma is placed into a preheated mold, and the mold is transferred to a heat treatment furnace and kept at 900°C for 1 hour. The temperature is then lowered to 650°C and kept at 650°C for 1 hour for annealing. Finally, the magma is cooled to room temperature in the furnace to obtain cast stone. The solid waste includes one of the following: carbide slag, waste gypsum or crystal slag and limestone. The specific ratio of pickling sludge to solid waste is pickling sludge: waste gypsum 85:15-92:8 or pickling sludge: carbide slag 80:20-90:10 or pickling sludge: crystal slag: limestone 75:20:5-80:16:

4. The pickling sludge mentioned above includes the pickling sludge contained in HW46.

2. The method for preparing cast stone using acid-washed sludge and solid waste according to claim 1, characterized in that: The melting furnace is a natural gas melting furnace with a melting temperature of 1400-1480℃, a melting time of 30-35 minutes, and a mold preheating temperature of 850-900℃.

3. The method for preparing cast stone using acid-washed sludge and solid waste according to claim 2, characterized in that: The siliceous material silo contains quartz sand or slag, and the calcareous material silo contains limestone.

4. The method for preparing cast stone using acid-washed sludge and solid waste according to claim 3, characterized in that: Both the chain conveyor and the conveying pipeline have weighing functions.

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