A method for preparing concrete using bioleaching residues of cobalt-molybdenum waste catalysts

Abstract

The present invention relates to a method for preparing concrete using bioleached residues of cobalt-molybdenum-based waste catalysts. The method involves mixing the bioleached residues, cement, standard sand, and water, stirring the mixture, performing a hydration reaction, and curing the resulting concrete. The advantages of this method are that the bioleached residues of cobalt-molybdenum-based waste catalysts, classified as HW50 hazardous waste, are used as a concrete admixture, reducing cement usage, improving concrete performance, and lowering production costs, thereby achieving resource utilization of waste.

Description

Technical Field

[0001] The invention belongs to the field of solid waste resource utilization and relates to a method for preparing concrete by utilizing bioleaching residues of cobalt-molybdenum series waste catalysts. Background Art

[0002] Cobalt-molybdenum waste catalysts are classified as HW50 hazardous waste. Bioleaching, a green, safe, cost-effective, and environmentally friendly technology, is currently being used to extract valuable metals from these waste catalysts. However, the remaining residue after leaching the valuable metals becomes a new solid waste. If not properly handled, it can become another environmental problem and lead to a waste of resources. To achieve the comprehensive utilization of solid waste, the government has introduced relevant incentives and support policies, creating a broad market for the application of waste catalysts in building materials such as cement and concrete. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for preparing concrete using bioleaching residues of cobalt-molybdenum waste catalysts. The bioleaching residues of cobalt-molybdenum waste catalysts are used as concrete admixtures, thereby reducing the amount of cement used, improving the working performance of concrete, reducing the production cost of concrete, and realizing the resource utilization of waste.

[0004] To achieve the above object, the present invention is implemented through the following technical solutions:

[0005] A method for preparing concrete using bioleaching residues of cobalt-molybdenum waste catalysts comprises mixing and stirring the bioleaching residues of cobalt-molybdenum waste catalysts, cement, standard sand and water, performing a hydration reaction and solidifying the concrete.

[0006] The cobalt-molybdenum series spent catalyst bioleaching residue, cement, standard sand and water are mixed according to the following weight parts:

[0007] 2.25-45 parts of bioleaching residue of spent cobalt-molybdenum catalyst;

[0008] 447.75-405 parts of cement;

[0009] 1350 parts of standard sand;

[0010] 225 parts of water.

[0011] The bioleaching residue of the cobalt-molybdenum series spent catalyst is the residue remaining after valuable metals are extracted by bioleaching.

[0012] The bioleaching method is to put the pretreated cobalt-molybdenum series waste catalyst into the bioleaching system to extract the valuable metals cobalt and molybdenum.

[0013] The pretreated cobalt-molybdenum waste catalyst is a gray powder obtained by crushing, grinding and roasting the cobalt-molybdenum waste catalyst.

[0014] The bioleaching system is a mixed leaching strain system, including two or more of Thiobacillus thiooxidans, Thiobacillus ferrooxidans, Leptospirillum ferrooxidans, energy substrates, and inorganic salt culture media. The energy substrates include sulfur and pyrite, and the inorganic salt culture media include two or more of (NH4)2SO4, KH2PO4, MgSO4·7H2O, CaCl2, and aspartic acid.

[0015] The cement is silicate cement with a strength grade of 42.5 or above.

[0016] The standard sand is a standard sand whose performance conforms to GB / T 17671-1999.

[0017] The cobalt-molybdenum waste catalyst bioleaching residue, cement, standard sand and water are mixed and stirred, poured into a mold, vibrated on a vibration table for more than 60 times, the surface is scraped flat, and placed in a constant temperature and humidity curing box at a temperature of 20.0±1.0°C for curing.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The present invention uses HW50 hazardous waste - cobalt-molybdenum series waste catalyst bioleaching residue as a concrete admixture, which reduces the amount of cement used, improves the working performance of concrete, reduces the production cost of concrete, and realizes the resource utilization of waste.

[0020] 2. Using bioleaching residues from waste cobalt-molybdenum catalysts as concrete admixtures greatly improves the strength of concrete;

[0021] 3. During the preparation of concrete by mixing the bioleaching residue of cobalt-molybdenum-based waste catalysts with cement, the hydration reaction occurs, which solidifies and stabilizes the residual metal elements in the bioleaching residue of cobalt-molybdenum-based waste catalysts, effectively reducing their leaching and secondary pollution to the environment;

[0022] 4. The bioleaching residue of cobalt-molybdenum spent catalysts contains a large amount of bacteria, EPS and organic metabolites, which are beneficial for repairing internal cracks in concrete and improving the strength of concrete;

[0023] 5. The bioleaching residue of cobalt-molybdenum waste catalyst replaces 10% of the total mass of cement, reducing the amount of cement used. While improving the working performance of concrete, it also reduces the production cost of concrete and realizes the resource utilization of waste. DETAILED DESCRIPTION

[0024] The present invention will be described in detail below, but it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0025] The method for preparing concrete using bioleaching residue of cobalt-molybdenum waste catalysts comprises the following steps: mixing the bioleaching residue of cobalt-molybdenum waste catalysts, cement, standard sand, and water; pouring the evenly mixed mortar into a 40×40×160 mm mold; vibrating the mold 60 times on a vibrating table; smoothing the surface; and placing the mold in a constant temperature and humidity curing chamber at a temperature of 20.0±1.0°C for curing at different ages (3 days, 28 days, and 56 days) to undergo hydration reaction and solidify into concrete.

[0026] The above-mentioned cobalt-molybdenum series spent catalyst bioleaching residue, cement, standard sand and water are mixed according to the following weight parts:

[0027] 2.25-45 parts of bioleaching residue of spent cobalt-molybdenum catalyst;

[0028] 447.75-405 parts of cement;

[0029] 1350 parts of standard sand;

[0030] 225 parts of water.

[0031] Adding 2.25 to 45 parts of bioleaching residue from waste cobalt-molybdenum catalysts to concrete can improve the long-term flexural strength and long-term compressive strength of concrete. When 45 parts of bioleaching residue from waste cobalt-molybdenum catalysts are added, the flexural and compressive strengths are 10.5 MPa and 60.1 MPa, respectively, at the age of 56 days. Adding 22.5 parts of bioleaching residue from waste cobalt-molybdenum catalysts to concrete can improve the early strength of concrete.

[0032] Bioleaching residues from spent cobalt-molybdenum catalysts are the residue remaining after valuable metals are extracted using bioleaching. These waste catalysts are generated during the petroleum refining process. They are black, spherical particles primarily composed of aluminum oxide, silicon oxide, molybdenum oxide, and cobalt oxide, along with other elements such as iron, arsenic, and sulfur.

[0033] Raw material processing: The cobalt-molybdenum spent catalyst is first crushed and ground to -200 mesh. After calcination at 400°C for 1 hour, a pretreated gray powder is obtained. This pretreated spent catalyst is then placed in a bioleaching system at a 10% (w / v) solid-to-liquid ratio to extract the valuable metals cobalt and molybdenum.

[0034] The bioleaching system is a mixed leaching strain system, which includes Thiobacillus thiooxidans, Thiobacillus ferrooxidans, Leptospirillum ferrooxidans, an energy substrate, and an inorganic salt culture medium. The energy substrate includes sulfur (8g / L) and pyrite (8g / L). The inorganic salt culture medium includes 2.0g / L (NH4)2SO4, 1g / L KH2PO4, 0.5g / L MgSO4·7H2O, 0.25g / L CaCl2, and 0.05g / L aspartic acid. The system is incubated in a constant temperature (35°C) water bath shaker at a speed of 135rpm for 8-10 days until the bacterial count reaches 3.2×10 8 / mL, used for metal leaching of spent catalysts.

[0035] Pretreated cobalt-molybdenum waste catalyst (solid-to-liquid ratio 10%) was added and leached at 35.5°C and 145 rpm for 9 days. The mixture was then centrifuged at 8000 rpm for 5 minutes. The leached residue was washed three times with pure water and then dried in a 60°C oven to constant weight to obtain bioleaching residue of the cobalt-molybdenum waste catalyst. The main components are aluminum oxide and silicon oxide, with small amounts of cobalt, molybdenum, sulfur and other elements, and may also contain other components.

[0036] According to the environmental protection industry standard HJ / T299-2007, toxicity leaching tests were conducted on all samples after a 56-day curing age using the sulfuric acid-nitric acid method. Metal concentrations in the leachate were measured using ICP-OES and compared with the toxic element leaching limits specified in GB5085.3-2007. The results showed that the addition of 2.25 to 45 parts of cobalt-molybdenum spent catalyst bioleaching residue kept the toxic element content in the leachate well below the limit.

[0037] Example 1

[0038] A concrete is prepared by mixing 4.5 g of bioleaching residue of a cobalt-molybdenum waste catalyst, 445.5 g of cement, 1350 g of standard sand, and 225 g of water. The evenly mixed mortar is poured into a 40×40×160 mm mold, and then vibrated 60 times on a vibrating table. After the surface is smoothed, the concrete is placed in a constant temperature and humidity curing chamber at a temperature of 20.0±1.0°C for curing at different ages (3 days, 28 days, and 56 days) to undergo a hydration reaction and solidify into concrete.

[0039] Example 2

[0040] A concrete is prepared by mixing 22.5 g of bioleached cobalt-molybdenum waste catalyst, 427.5 g of cement, 1350 g of standard sand, and 225 g of water. The evenly mixed mortar is poured into a 40×40×160 mm mold, then vibrated 60 times on a vibrating table. After the surface is smoothed, the concrete is placed in a constant temperature and humidity curing chamber at a temperature of 20.0±1.0° C. for curing at different ages (3 days, 28 days, and 56 days) to undergo hydration reaction and solidify into concrete.

[0041] Example 3

[0042] A concrete is prepared by mixing 45 g of bioleaching residue of a cobalt-molybdenum waste catalyst, 405 g of cement, 1350 g of standard sand, and 225 g of water. The evenly mixed mortar is poured into a 40×40×160 mm mold, and then vibrated 60 times on a vibrating table. After the surface is smoothed, the concrete is placed in a constant temperature and humidity curing chamber at a temperature of 20.0±1.0°C for curing at different ages (3 days, 28 days, and 56 days) to undergo a hydration reaction and solidify into concrete.

[0043] Comparative Example 1

[0044] A concrete is prepared by mixing 0g of bioleaching residue of a cobalt-molybdenum waste catalyst, 450g of cement, 1350g of standard sand, and 225g of water. The evenly mixed mortar is poured into a 40×40×160mm mold, and then vibrated 60 times on a vibrating table. After the surface is smoothed, the concrete is placed in a constant temperature and humidity curing chamber at a temperature of 20.0±1.0°C for curing at different ages (3 days, 28 days, and 56 days) to undergo a hydration reaction and solidify into concrete.

[0045] The concrete indicators prepared in the above examples and comparative examples are shown in Table 1.

[0046] Table 1: Parameter list of each embodiment:

[0047]

Claims

1. A method for preparing concrete using bioleaching residues of cobalt-molybdenum waste catalysts, characterized in that: The waste bioleaching residue of cobalt-molybdenum catalyst, cement, standard sand and water are mixed and stirred to carry out hydration reaction and solidify into concrete; The cobalt-molybdenum series spent catalyst bioleaching residue, cement, standard sand and water are mixed according to the following weight parts: 2.25-45 parts of bioleaching residue of spent cobalt-molybdenum catalyst; Cement 447.75~405 parts; 1350 parts of standard sand; 225 parts water; The cobalt-molybdenum waste catalyst bioleaching residue is the residue remaining after the valuable metals are extracted by bioleaching. The cobalt-molybdenum waste catalyst is a waste catalyst generated during the petroleum refining process. It is in the form of black spheres and its main components are aluminum oxide, silicon oxide, molybdenum oxide, cobalt oxide, and also contains other elements such as iron, arsenic, and sulfur. The bioleaching method is to place the pretreated cobalt-molybdenum series waste catalyst into the bioleaching system to extract the valuable metals cobalt and molybdenum; The pretreated cobalt-molybdenum waste catalyst is a gray powder obtained by crushing, grinding and calcining the cobalt-molybdenum waste catalyst; The bioleaching system is a mixed leaching strain system, including Thiobacillus thiooxidans, Thiobacillus ferrooxidans, Leptospirillum ferrooxidans, energy substrates, and inorganic salt culture medium. The energy substrates include sulfur and pyrite, and the inorganic salt culture medium includes two or more of (NH4)2SO4, KH2PO4, MgSO4·7H2O, CaCl2, and aspartic acid.

2. The method for preparing concrete using bioleaching residues of cobalt-molybdenum waste catalysts according to claim 1, characterized in that: The cement is silicate cement with a strength grade of 42.5 or above.

3. The method for preparing concrete using bioleaching residues of cobalt-molybdenum waste catalysts according to claim 1, characterized in that: The standard sand is a standard sand whose performance conforms to GB / T 17671-1999.

4. The method for preparing concrete using bioleaching residues of cobalt-molybdenum waste catalysts according to claim 1, characterized in that: The cobalt-molybdenum waste catalyst bioleaching residue, cement, standard sand and water are mixed and stirred, poured into a mold, vibrated on a vibration table for more than 60 times, the surface is scraped flat, and placed in a constant temperature and humidity curing box at a temperature of 20.0±1.0°C for curing.

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