A method for producing copper-doped tailings road base material

Abstract

The present invention belongs to the technical field of copper tailings resource recycling, and in particular, is a method for producing a copper tailings-doped road base material. The present invention comprises the following steps: S1, through a staged mixture, determining the blending ratio of copper tailings and aggregates of various particle sizes, preparing 5-10 kg of copper tailings-doped road base material according to the blending ratio, uniformly mixing for 2-3 minutes, then sieving the uniformly mixed mixture to remove aggregates, taking the copper tailings at the bottom of the sieve, and measuring its moisture content, and calculating the amount of water added when mixing the copper tailings-doped road base material; putting the copper tailings, aggregates of various particle sizes, and cement into a mixing station and mixing for 20-25 seconds, adding the above-calculated amount of water and mixing for 10-15 seconds, and preparing the copper tailings-doped road base material. The present invention scientifically and effectively controls the amount of water added to ensure that the copper tailings-doped road base material has good performance.

Description

Technical Field

[0001] The invention belongs to the field of copper tailings resource recycling, and in particular relates to a method for producing copper-doped tailings pavement base material. Background Art

[0002] Copper tailings refer to the solid waste remaining after the useful components in the ore are screened out through the mineral processing process in mines that mainly mine copper resources. Under normal circumstances, more than 98% of the components in copper ore become tailings after refining, and the accumulation of copper tailings requires the occupation of land, affecting the normal production and use of mining enterprises.

[0003] Semi-rigid subbase materials offer high early strength, excellent plate properties, and strong diffusion stress. Existing pavement subbases primarily utilize semi-rigid materials. Copper tailings, with similar composition and mechanical properties to sand and gravel, have the potential to replace natural aggregates. Using semi-rigid materials prepared from copper tailings for use as pavement subbases offers a promising path to maximize the value of copper tailings. To use copper tailings as aggregate for pavement subbases, a filter press process is required to dehydrate the copper tailings. Currently, the moisture content of dehydrated copper tailings is between 12-16%. This is then blended with natural aggregate to create the copper-tailings-infused pavement subbase material.

[0004] In the current design and construction specifications for pavement subbase materials, a compaction test method is used to determine the optimal moisture content of the base material. Based on the moisture content of the raw materials, a blending method is used to determine the amount of water added during the production and preparation of the pavement subbase material. For natural aggregates, their moisture content is generally very low and usually negligible. The amount of water added is the optimal moisture content, while the moisture content of copper tailings is 12-16%. If the blending method is used, when the copper tailings content reaches more than 25%, very little or no water will be added. However, in fact, after the copper tailings are mixed with the aggregate, the water in the copper tailings cannot make the copper tailings and aggregate surfaces have the same water film thickness, and the aggregate surface cannot form an infiltration effect, and thus cannot undergo an effective chemical reaction with cement, resulting in the strength of the copper tailings-added pavement base material not meeting the standards. Summary of the Invention

[0005] In order to overcome the above-mentioned defects in the prior art, the present invention provides a method for producing a copper-doped tailings road base material. The present invention scientifically and effectively controls the amount of water added to ensure that the copper-doped tailings road base material has better performance.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for producing a copper-doped tailings road base material, comprising the following specific steps:

[0008] S1. After the graded mixture is formed, the mixing ratio of copper tailings and aggregates of various particle sizes is determined. According to the mixing ratio, 5-10 kg of copper tailings-added road base material is prepared and evenly mixed for 2-3 minutes. The evenly mixed mixture is then sieved to remove the aggregates. The copper tailings at the bottom of the sieve are taken and their moisture content P is measured. h , calculate the amount of water to be added when mixing the copper tailings-doped road base material. The water addition calculation formula is as follows:

[0009] ;

[0010] ;

[0011] ;

[0012] ;

[0013] ;

[0014] Where:

[0015] SA w ——Specific surface area of ​​copper tailings, m 2 / kg;

[0016] ρ w ——Density of dried copper tailings, g / cm 3 ;

[0017] r w ——Average particle size of copper tailings, mm;

[0018] u p ——Average water film thickness of copper tailings-added road base material under optimal moisture content, um;

[0019] P z ——Optimal moisture content determined by compaction test of copper-doped tailings road base material, %;

[0020] ρ s ——Density of water, g / cm 3 ;

[0021] SA1——Specific surface area of ​​20-30mm particle size aggregate, m 2 / kg;

[0022] P1——Proportion of 20-30mm particle size aggregate in copper tailings-added road base material, %;

[0023] SA2——Specific surface area of ​​10-20mm particle size aggregate, m 2 / kg;

[0024] P2——Proportion of 10-20mm particle size aggregate in the copper tailings-added road base material, %;

[0025] SA3——Specific surface area of ​​5-10mm particle size aggregate, m 2 / kg;

[0026] P3——Proportion of 5-10mm particle size aggregate in the copper tailings-added road base material, %;

[0027] SA4——Specific surface area of ​​3-5mm particle size aggregate, m 2 / kg;

[0028] P4——Proportion of 3-5mm aggregate in the copper tailings-added road base material, %;

[0029] P w ——The proportion of copper tailings in the copper tailings-mixed road base material, %;

[0030] SA s ——cement specific surface area, m 2 / kg;

[0031] P s ——Cement ratio in the base material of copper tailings-added road surface, %;

[0032] u z ——The thickness of the water film on the aggregate surface after the water in the copper tailings is transferred to the aggregate, um;

[0033] ɑ——Surface water transfer coefficient of copper tailings after mixing;

[0034] P ws ——Moisture content of copper tailings, %;

[0035] P j ——The amount of water added when mixing the copper tailings-added road base material, %;

[0036] u g ——Thickness of water film on the surface of copper tailings in natural undried state, μm;

[0037] S2. The copper tailings, aggregates of various particle sizes, and cement are put into a mixing station and mixed for 20-25 seconds. The above-calculated amount of water is added and mixed for 10-15 seconds to prepare a copper tailings-doped road base material.

[0038] Preferably, in step S1, before the copper tailings-doped road base material is evenly mixed, the copper tailings are dried in an oven and the moisture content P of the copper tailings is measured. wsThe aggregates of various particle sizes and the dried copper tailings are screened to determine the particle size composition of each raw material, and then graded and synthesized to determine the blending ratio of aggregates of various particle sizes and copper tailings. The cement ratio P in the copper tailings-added road base material is determined based on the relevant mix ratio design test. s , optimal moisture content P z .

[0039] Preferably, in step S1, the method for determining the specific surface area of ​​aggregates of various particle sizes is as follows: weigh 500-1000 g of aggregate, soak the weighed aggregate in alcohol, filter it, place it in a sealed container and centrifuge it for 2-3 minutes, and place absorbent paper at the bottom of the container; weigh the mass of the aggregate after centrifugation; then dry it and weigh the mass of the dried aggregate, and calculate the specific surface area of ​​the aggregate based on the thickness of the alcohol film on the surface of the aggregate and the volume of the adsorbed alcohol.

[0040] Preferably, the specific surface area of ​​the aggregate is calculated according to the following formula:

[0041] ;

[0042] Where:

[0043] SA——Specific surface area of ​​aggregate, m 2 / kg;

[0044] m s ——mass of aggregate after centrifugal rotation with alcohol, g;

[0045] m g ——mass of aggregate after drying, g;

[0046] m k ——mass of aggregate at the time of sampling, g;

[0047] μ j ——Thickness of alcohol film, μm;

[0048] r j ——Density of alcohol, g / cm 3 .

[0049] Preferably, in step S1, the copper tailings are equivalent to a sphere, and the calculation formula for the water film thickness on the surface of the copper tailings in a natural undried state is as follows:

[0050] ;

[0051] ;

[0052] Where:

[0053] r w ——Average particle size of copper tailings, mm;

[0054] r i ——sieve hole size, mm;

[0055] r i+1 ——Size of the sieve hole of the previous sieve of the i-th sieve, mm;

[0056] Q i ——Copper tailings in the sieve hole The sieve residue, %;

[0057] u g ——Thickness of water film on the surface of copper tailings in natural undried state, μm;

[0058] P ws ——Moisture content of copper tailings, %;

[0059] r w ——Density of dried copper tailings, g / cm 3 ;

[0060] r s ——Density of water, g / cm 3 .

[0061] Preferably, in step S1, after the copper tailings are evenly mixed with aggregates of various particle sizes, the surface water transfer coefficient of the copper tailings is calculated according to the following formula:

[0062] ;

[0063] Where:

[0064] ɑ——Surface water transfer coefficient of copper tailings after mixing;

[0065] P h ——After the copper tailings are evenly mixed with aggregates of various particle sizes, the moisture content of the copper tailings is %;

[0066] P ws ——Moisture content of copper tailings, %.

[0067] Preferably, the particle size of the copper tailings is ≤2.36 mm.

[0068] Preferably, the thickness of the alcohol film is 10-16 μm, and the time for the aggregates of various particle sizes to be immersed in alcohol is ≥12 h.

[0069] Preferably, the cement ratio P in the copper tailings-added road base material is s 3.0%-4.5%; the specific surface area of ​​cement is 350-400m 2 / kg.

[0070] Preferably, the aggregates of various particle sizes are 20-30 mm, 10-20 mm, 5-10 mm, and 3-5 mm.

[0071] The advantages of the present invention are:

[0072] (1) The method of the present invention analyzes the changes in the water film thickness on the surfaces of copper tailings and aggregates during the mixing process of copper tailings and aggregates and the water transfer process from a microscopic perspective, and ensures that the surfaces of copper tailings, aggregates of various particle sizes, and cement can eventually reach the maximum water film thickness state. According to the changes in the water film thickness on the surfaces of copper tailings and aggregates after the water in the copper tailings is partially transferred to the aggregates, the amount of water added during the mixing process is calculated, thereby providing a scientific and effective method for determining the amount of water added to copper tailings-doped road base materials.

[0073] (2) The present invention prepares a mixture of copper tailings and aggregates according to the ratio of the copper tailings-doped road base material, accurately simulates the water transfer process during the mixing of copper tailings and aggregates, and proposes a method for calculating the water transfer coefficient during the mixing of copper tailings, thereby ensuring the accuracy of the calculation of the amount of water added in the production and preparation of the copper tailings-doped road base material and guaranteeing the material performance.

[0074] (3) During the mixing process of the copper tailings and aggregates of the present invention, part of the water in the copper tailings is transferred to the aggregates. Considering the thickness of the water film on the surface of the copper tailings and aggregates after the transfer, the average water film thickness on the surface of the cement, aggregates and copper tailings at the optimal moisture content is taken as the target value. The amount of water added during the mixing process is calculated so that the surfaces of various raw materials reach the optimal water infiltration state, which is conducive to the interaction between the raw materials and the better performance. DETAILED DESCRIPTION

[0075] A method for producing a copper-doped tailings road base material comprises the following steps:

[0076] S1. Take samples of copper tailings and measure their moisture content P ws The water density is 13.6%, and the water density is 1g / cm 3 , drying copper tailings, drying copper tailings density r w 2.71g / cm 3 The dried copper tailings, 20-30mm aggregate, 10-20mm aggregate, 5-10mm aggregate, and 3-5mm aggregate were screened. The results are shown in Table 1 below:

[0077] Table 1

[0078] ;

[0079] S2. The grading synthesis is performed. The grading synthesis results of copper tailings, 20-30 mm particle size aggregate, 10-20 mm particle size aggregate, 5-10 mm particle size aggregate, and 3-5 mm particle size aggregate are shown in Table 2 below:

[0080] Table 2 Blending ratio

[0081] ;

[0082] S3. According to the "Testing Procedures for Inorganic Binder Stabilized Materials for Highway Engineering" (JTG 3441), a mix design test was conducted to determine the cement ratio P in the copper tailings-added road base material. s , optimal moisture content P z , the maximum dry density is shown in Table 3 below:

[0083] Table 3

[0084] ;

[0085] S4. Weigh 20-30mm, 10-20mm, 5-10mm, and 3-5mm aggregates respectively. Soak the four aggregates in alcohol for 15 hours, filter them, and centrifuge them in a sealed container for 2-3 minutes. Place absorbent paper at the bottom of the container and weigh the mass of each sample after centrifugation. Dry the aggregates and weigh the mass of each aggregate after drying. According to the thickness of the alcohol film on the surface of each aggregate and the volume of adsorbed alcohol, the thickness of the alcohol film μ is calculated. j Take 14um, alcohol density r j Taking 0.789 g / cm³, the specific surface area of ​​each aggregate was calculated according to the following formula. The results are shown in Table 4 below:

[0086] ;

[0087] Table 4

[0088] ;

[0089] S5. Treat the copper tailings as a sphere and calculate the water film thickness u on the surface of the copper tailings in its natural, undried state. g , calculated according to the following formula:

[0090] =0.31mm;

[0091] =19um;

[0092] S6. Prepare 8 kg of copper tailings-doped road base material at a ratio of 30% copper tailings, 15% 20-30 mm aggregate, 23% 10-20 mm aggregate, 26% 5-10 mm aggregate, and 6% 3-5 mm aggregate. Mix the mixture evenly for 2-3 minutes. Pass the mixture through a 2.36 mm sieve. Take the copper tailings at the bottom of the sieve and determine its moisture content to be 9.6%. Calculate the water transfer coefficient of the copper tailings according to the following formula:

[0093] =0.31;

[0094] S7. Control requirements for the surface water film thickness of aggregate and cement at the optimum moisture content of the copper tailings-added road base material. The specific surface area of ​​cement is 360m 2 / kg. During the mixing process of copper tailings with 20-30mm aggregate, 10-20mm aggregate, 5-10mm aggregate, and 3-5mm aggregate, some water is transferred to the 20-30mm aggregate, 10-20mm aggregate, 5-10mm aggregate, and 3-5mm aggregate. Calculate the amount of water added when mixing the copper tailings-added road base material using the following formula:

[0095] =7.14m 2 / kg;

[0096] =2.63um;

[0097] =0.87um;

[0098] =2.55%;

[0099] ;

[0100] S8. According to the mix design results, 30% copper tailings, 15% 20-30mm aggregate, 23% 10-20mm aggregate, 26% 5-10mm aggregate, 6% 3-5mm aggregate, and 3.5% cement were added to the mixing station and mixed for 23 seconds. Then, 2.55% water was added and mixed for 12 seconds to prepare the copper tailings-doped pavement base material. The mixed pavement subbase material was constructed, and the pavement after construction was tested as shown in Table 5 below. The results met the requirements of the specification.

[0101] Table 5 Test results of copper-doped tailings road base materials after construction

[0102] ;

[0103] The above are only preferred embodiments of the present invention and are 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 in the scope of protection of the present invention.

Claims

1. A method for producing copper-doped tailings road base material, characterized in that: The specific steps are as follows: S1. After the graded mixing, determine the mixing ratio of copper tailings and aggregates of various particle sizes. Prepare 5-10kg of copper tailings-added road base material according to the mixing ratio, mix evenly for 2-3 minutes, then sieve the evenly mixed mixture to remove aggregates, take the copper tailings at the bottom of the sieve, and measure its moisture content. Calculate the amount of water to be added when mixing the copper tailings-added road base material. The water addition calculation formula is as follows: ； ； ； ； ； Where: SA w ——Specific surface area of ​​copper tailings, m 2 / kg; ρ w ——Density of dried copper tailings, g / cm 3 ; r w ——Average particle size of copper tailings, mm; u p ——Average water film thickness of copper tailings-added road base material under optimal moisture content, um; P z ——Optimal moisture content determined by compaction test of copper-doped tailings road base material, %; ρ s ——Density of water, g / cm 3 ; SA1——Specific surface area of ​​20-30mm particle size aggregate, m 2 / kg; P1——Proportion of 20-30mm particle size aggregate in copper tailings-added road base material, %; SA2——Specific surface area of ​​10-20mm particle size aggregate, m 2 / kg; P2——Proportion of 10-20mm particle size aggregate in the copper tailings-added road base material, %; SA3——Specific surface area of ​​5-10mm particle size aggregate, m 2 / kg; P3——Proportion of 5-10mm particle size aggregate in the copper tailings-added road base material, %; SA4——Specific surface area of ​​3-5mm particle size aggregate, m 2 / kg; P4——Proportion of 3-5mm aggregate in the copper tailings-added road base material, %; P w ——The proportion of copper tailings in the copper tailings-mixed road base material, %; SA s ——cement specific surface area, m 2 / kg; P s ——Cement ratio in copper tailings-added road base material, %; u z ——The thickness of the water film on the aggregate surface after the water in the copper tailings is transferred to the aggregate, um; ——Surface water transfer coefficient of copper tailings after mixing; P ws ——Moisture content of copper tailings, %; P j ——The amount of water added when mixing the copper tailings-added road base material, %; u g ——Thickness of water film on the surface of copper tailings in natural undried state, μm; S2. Add the copper tailings, aggregates of various particle sizes, and cement to a mixing station and mix for 20-25 seconds. Add the water calculated above and mix for 10-15 seconds to prepare a copper tailings-doped road base material. In step S1, before the copper tailings-doped road base material is evenly mixed, the copper tailings are dried in an oven, the moisture content of the copper tailings is measured, the aggregates of various particle sizes and the dried copper tailings are screened, the particle size composition of each raw material is determined, and the graded mixture is performed to determine the blending ratio of the aggregates of various particle sizes and the copper tailings, and the cement ratio and the optimal moisture content in the copper tailings-doped road base material are determined according to relevant mix ratio design experiments; The specific surface area of ​​aggregates of various particle sizes is determined as follows: 500-1000g of aggregate is weighed, the aggregate is immersed in alcohol, filtered, and then centrifuged in a sealed container for 2-3 minutes with absorbent paper placed at the bottom of the container; the mass of the aggregate after centrifugation is weighed; the aggregate is then dried and weighed; the specific surface area of ​​the aggregate is calculated based on the thickness of the alcohol film on the aggregate surface and the volume of adsorbed alcohol; The specific surface area of ​​aggregate is calculated according to the following formula: ； Where: SA——Specific surface area of ​​aggregate, m 2 / kg; m s ——mass of aggregate after centrifugal rotation with alcohol, g; m g ——mass of aggregate after drying, g; m k ——mass of aggregate at the time of sampling, g; μ j ——Thickness of alcohol film, μm; ρ j ——Density of alcohol, g / cm 3 ; In step S1, the calculation formula for the water film thickness on the surface of the copper tailings in the natural undried state is as follows: ； ； Where: r w ——Average particle size of copper tailings, mm; r i ——sieve hole size, mm; r i+1 ——Size of the sieve hole of the previous sieve of the i-th sieve, mm; Q i ——Copper tailings in the sieve hole The sieve residue, %; u g ——Thickness of water film on the surface of copper tailings in natural undried state, μm; P ws ——Moisture content of copper tailings, %; ρ w ——Density of dried copper tailings, g / cm 3 ; ρ s ——Density of water, g / cm 3 ; In step S1, after the copper tailings are evenly mixed with aggregates of various particle sizes, the surface water transfer coefficient of the copper tailings is calculated according to the following formula: ； Where: ——Surface water transfer coefficient of copper tailings after mixing; P h ——After the copper tailings are evenly mixed with aggregates of various particle sizes, the moisture content of the copper tailings is %; P ws ——Moisture content of copper tailings, %.

2. The method for producing a copper-doped tailings road base material according to claim 1, wherein: The particle size of the copper tailings is ≤2.36 mm.

3. The method for producing a copper-doped tailings road base material according to claim 1, wherein: The thickness of the alcohol film is 10-16 μm, and the time for the aggregates of various particle sizes to be immersed in alcohol is ≥12 h.

4. The method for producing a copper-doped tailings road base material according to claim 1, wherein: The cement ratio in the copper-doped tailings road base material is 3.0%-4.5%; the specific surface area of ​​the cement is 350-400m 2 / kg.

5. The method for producing a copper-doped tailings road base material according to claim 1, wherein: The aggregates of various particle sizes are 20-30 mm, 10-20 mm, 5-10 mm, and 3-5 mm.

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