Ordinary wall bricks are one of the largest building materials used in the construction industry, and the state has developed a series of measures to protect cultivated land in order to protect agricultural production. Therefore, the clay resources of brick making are becoming more and more tense, and the use of tailings bricks is A good way. The use of tailings bricks should be studied from the brick structure and processing technology to produce economical, durable and lightweight products as early as possible.
First, iron tailings brick
1. Iron tailings made of non-burning bricks
Maanshan Mine Research Institute successfully used the tailings of Qidashan and Shantoushan iron ore to form non-burning bricks. The non-burning wall bricks are made of fine tailings (SiO 2 >70%). A small amount of aggregate, calcium cementitious material and admixture are added, and an appropriate amount of water is added, uniformly stirred, and then molded under a pressure of 19.6 to 114.7 MPa on a 60-ton press, and subjected to standard curing (natural curing) for 28 days after demolding. , into the finished product, the process flow is shown in Figure 1. The two tailings bricks of Qi Dashan and Shantou Mountain have been tested, and all the indicators have met the requirements of No. 100 standard bricks stipulated in the Technical Conditions for Non-sintered Clay Bricks promulgated by the State Bureau of Building Materials.
Figure 1 Production process of tailings-free brick
Dalian University of Technology collaborates with Dagangshan Iron Mine of Anshan Iron and Steel Co., Ltd., using iron tailings and lime as the main raw materials, adding appropriate amount of modified materials and admixtures, and developing the steamed tailings bricks with better physical properties. Can meet the requirements of standard bricks above 100.
Meishan Meishan iron ore processing plant using a number of sand tailings added (Ore: sand = 3: 1) was added 3% of cement, from 8% to 10% water and 2% to 3% of additives F-1, made A standard brick sample of 240 mm × 115 mm × 53 mm is then subjected to various tests such as flexural strength, compressive strength and fire resistance. The main technical indicators have reached the requirements of the technical conditions of non-sintered clay bricks, the number can reach above 75.
2, iron tailings production machine pressed sand brick
Ridge Iron Concentrator characteristics of gold mine, using a pressing machine tailings sand-lime brick, the brick is mainly iron tailing, adding an appropriate amount of cement was prepared by dry mixing evenly, then add a small amount of binder material is compacted, Improve its surface activity, after being pressed and formed by a brick press, it is naturally cured. The process is simple, no fire, no steam curing, which saves energy (standard coal per million bricks savings of about 0.16t than clay brick), and non-polluting, the production of sand-lime brick accurate size, angular, neat appearance, The brick body is straight, which can save the amount of plastering, improve the efficiency and reduce the cost. The mine was completed in October 1989. The production of lime sand bricks has been tested, and the physical performance indicators have reached the technical requirements of No. 100 standard for mechanically pressed lime sand bricks.
3. Iron tailings to make carbonized tailings bricks
The Yuquanling Iron Mine has developed and utilized tailings as a carbonized tailings brick since 1986, and has achieved results. The carbonized tailings brick is a masonry material which is made of tailings sand and lime as raw materials, prepared by billet, pressed and formed, and carbonized by carbon dioxide (CO 2 ) of lime kiln exhaust gas.
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Principle A
The semi-finished product of the carbonized lime sand brick is firstly formed by the hydration and hardening of the quicklime, firstly, the calcium hydroxide crystal is formed, and then carbonized by the lime kiln exhaust gas carbon dioxide (CO 2 ), and finally the calcium carbonate crystal (CaCO 3 ) is formed, and the water is combined with the water. The product is evaporated and the product is finally carbonized. The chemical reaction process is as follows:
CaO + H 2 O → Ca(OH) 2
Ca (OH) 2 +nH 2 O+CO 2 →CaCO 3 +(n+1)H 2 O
B process
80% to 85% of tailings sand and 15% to 20% of quicklime powder are proportioned, and about 9% of water is added to stir and dissolve. Then, it is formed by an eight-hole brick press, dried before drying in the kiln or naturally dried. Less than 4%, then enter the tunnel kiln for carbonization, carbonized carbon dioxide content of 20% to 40%, carbonization depth of more than 60%, after the kiln can get the finished product.
The brick production process is simple, the machine and the soil sample are all available, and there are no technical problems that are difficult to grasp. Any tailings sand and limestone can be mass produced.
Second, lead zinc tailings Brick
1, refractory bricks and red bricks
In the production process of the tailings of Hunan Shaodong lead-zinc concentrator in the recovery of fluorite by branch flotation, the main component of the partial flotation of the first flotation tailings by hydrocyclone is silica and alumina. Its refractoriness is 1680 °C. Using the overflow product, a part of 2.362mm clay clinker and mud is added, and these materials are naturally air-dried after being kneaded and formed, dried at 80 ° C and 120 ° C, and then fired in a re-burning furnace to obtain The final product, its performance has been tested to meet the national blast furnace brick standard.
Part of the tailings produced in the flotation process for the recovery of fluorite are rich in silica and calcium fluoride.
If the return to the fluorite flotation circuit will affect the quality of the fluorite concentrate, it will be produced as part of a separate tailings. In order to make this part of the tailings properly used, a red brick test was carried out. The tailings and clay are mixed in a ratio of 3:2, and then dried (120 ° C, 4 h), fired (1000 ° C, 3 h) to obtain the finished product.
2, autoclaved silicate brick
Jiangxi Copper companies under the chemical composition of lead-zinc tailings Hill silver relatively stable, the main components: SiO 2 58.52%, Al 2 O 3 11.42%, Fe 2 O 3 8.74%, CaO 0.23%, MgO 0.42%, burn The loss is 1.3%~1.5%, and the particle size composition is ideal. The particle size and occupancy rate are: +0.175mm, 18.50%, +0.124mm, 7.25%, +0.074mm, 17.00%, and +0.048mm, 10.50%. -0.048mm accounted for 46.75%, suitable
It should be used to produce autoclaved silicate bricks. The production process is shown in Figure 2.
Figure 2 Production process of autoclaved silicate brick in Yinshan lead-zinc mine
Technical requirements for the process:
Proportion: 85% tailings, 15% lime;
Calcium oxide content: 65% or more;
Digestion temperature: 80 ° C or more;
Digestion time: 6h;
Steam pressure: 0.8MPa;
Steam temperature: 170 ° C or more.
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The finished bricks produced are high in strength and beautiful in color. After testing, its compressive strength is 18～21MPa, the flexural strength is 3.7～5.5MPa, the antifreeze performance is good (17 freeze fusion grids), other physical properties are all, meet the requirements of use, the test result is the national standard 150 brick It is higher than ordinary clay bricks and can be widely used in general industrial and civil buildings.
At present, Yinshan Lead-Zinc Mine has built a tailings brick factory with a capacity of 10 million pieces. It can consume 30,000 tons of tailings per year, and the product quality is good, the customer is satisfied, the sales are wide, the estimated annual output value is 1.6 million yuan, and the profit and tax is 170,000. yuan.
Third, copper tailings brick
A lime sand brick
The Yueshan Copper Mine produces 75,000 tons of tailings per year, and the current stockpiles amount to more than 1.1 million tons. The copper tailings of this mine are quartz -based fine sand composed of more than ten kinds of minerals. No comprehensive recovery value. The mine has been extensively tested using tailings to make bricks and has been successful.
1, the nature of raw materials
From the data of sand used in domestic lime sand brick factory, the main component of silica is generally not less than 65%, and the harmful component mica should not be too high. The main chemical composition of tailings in this mine is SiO 2 60.43%, Al 2 O 3 14.27%, Fe 2 O 3 4.69%, CaO 6.22%, MgO 1.40%, K 2 O 3.4%, Na 2 O 3.86%, basic Meet the requirements for brick making.
2, the production process
The tailings and lime are used as raw materials (adding coloring agent admixture), prepared by blanking, compression molding, and saturated autoclave curing.
The gauze bricks produced have been inspected and the quality has reached the ministerial standard. The appearance indicators are first-class bricks, and their technical indicators exceed those of red bricks. Its utilization prospects are broad.
Fourth, gold tailings brick
A ceramic wall and floor tiles
Shandong Institute of Building Materials used the tailings of Jiaojia Gold Mine to add a small amount of local cheap clay to develop ceramic wall and floor tiles that meet the national standards.
1, the main raw materials
The main raw materials are gold tail sand and Fangzi soil. The tailings are selected from the tailings of Jiaojia Gold Mine. The main minerals are: SiO 2 , NaAlSi 3 O 8 , KalSi 3 O 8 , NaCl, Al 2 O 3 · SiO 2 ( andalusite ). Fangzi soil is a local clay. If the source is difficult, it can be replaced by other similar clay.
2, the production process
The production process is: batching → adding water stirring → wheel milling powder → trapping material → 100t friction press molding → 60min roller dryer drying → roller kiln firing (90min) → prime inspection → glazing → roller kiln glaze burning (90min) → Check the package. Among them, the ingredients are 18%, and the water content of the tailings is about 8% to 17%. The amount of water can be adjusted according to actual needs during production. The burnt and glaze burned according to the 50m coal-fired roller kiln, the firing cycle was 90min, and the firing temperature was 1140～1180°C. The glaze formula is shown in Table 1.
Table 1 Glaze Formula (%)
name | Feldspar | quartz | Kaolin | limestone | fluorite | Burned ZnO | Zircon sand | Frit | Burning talc |
1 | 40 | twenty one | 12 | 4 | 5 | 4 | 5 | 3 | 6 |
2 | 46 | 11 | 5 | 5 | 3 | 3 | 10 | 11 | 6 |
In the table, 1 is the bottom glaze, and 2 is the surface glaze. In the actual production process, the factory can choose different vegetable glazes and art glazes according to the current market conditions and user requirements, thus increasing the added value of the products.
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The fired products have been tested and their physical properties are in compliance with relevant national standards. The dimensions and appearance quality also conform to the relevant national standards.
The use of gold tail sand to produce ceramic wall and floor tiles products, compared with the production of cement-free bricks, low cost and high price, opened up a new way for the use of tailings.
Five, tungsten tailings brick
The calcified brick factory of Xihuashan Tungsten Mine was completed in 1989. It was put into mass production in 1990. It produces calcified bricks from tailings and lime. The annual production of bricks reaches 10 million pieces, and the annual profit is more than 200,000 yuan.
1. Main raw materials and quality requirements
Calcified brick is also known as lime sand brick. Its main raw material is tailings and lime. The tailings are tailings produced by Xihuashan tungsten ore. The chemical composition and particle size distribution are shown in Table 2 and Table 3.
Table 2 Tail sand size composition table
Size/mm | 1.651 | 0.833 | 0.351 | 0.246 | 0.175 | 0.147 | 0.097 | 0.074 | -0.074 |
Quality score /% | 2.05 | 26.15 | 21.82 | 14.77 | 7.65 | 6.42 | 7.12 | 4.54 | 9.48 |
Grand total/% | 2.05 | 28.2 | 50.02 | 64.79 | 72.44 | 78.68 | 85.98 | 90.52 | 100.0 |
Table 3 Table of chemical composition of tailings (%)
chemical components | WO 3 | Mo | Bi | Fe | Mn | CaF 2 | CaO | K 2 O | Na 2 O | SiO 2 | As | S | Sn |
Quality score | 0.04 | 0.01 | 0.01 | 1.69 | 0.09 | 0.53 | 0.53 | 3.14 | 1.88 | 71.16 | 0.01 | 0.108 | 0.004 |
The tailings account for more than 80% of the total amount of calcified bricks. It is necessary to ensure that the content of silica in the tailings is more than 65%. In addition, the tailings are not allowed to contain agglomerated clay blocks, and the finely dispersed fine-grained soil content is not allowed. It should be less than 10% of the total amount; the content of water-soluble potassium and sodium oxide should not exceed 2%; the particle size requirement is 0.31.2mm>65%, +1.2mm<5%, -0.15mm does not exceed 30%, and the tail Sand does not allow the presence of large and small pebbles, slag, grass roots, bark and other debris.
Lime: Lime must be fresh (bulk) of lime, and the content of calcium oxide should be greater than 65% efficient, magnesium oxide content should be less than 5% of the low magnesium lime, while the burnt lime and lime should be burnt separately under Less than 5% and 15% are optimal, and the fineness requirement is -0.097 mm>95%.
2, the production process
After the lime is processed and pulverized, it is mixed with the tailing sand for removing impurities, stirred with water, and then digested into a warehouse, pressed and formed, and steamed to become a finished product.
In the process of mixing sand and sand, in order to disperse the sand and sand to achieve uniform mixing, mechanical agitation should be used to enlarge the contact surface of ash and sand, control the amount of water added, and the lime can be fully digested to generate as much hydration as possible. product. The theoretical water addition amount is 33.13% of the effective calcium oxide content. When digested in an open container, the actual water addition amount is 1-2 times of the theoretical water addition amount; the mixing digestion time is generally within 30 minutes, and the temperature needs to be controlled above 55 °C.
Brick forming is an important means to ensure the quality of calcified bricks. Calcified bricks are formed by semi-dry pressing, and the moisture content is only 8% to 10%. To ensure that the weight of the brick reaches 2.75 ~ 2.89kg / block, the ultimate forming pressure must reach 20MPa (or 200kg / cm 2 ) or more, the filling depth is 80 ~ 85mm, the finished product size is 240mm × 115mm × 53mm.
Autoclaved curing generally uses a saturated vapor pressure of 0.8 MPa (or 8 kg/cm 2 ) and autoclaved for 6 h.
After testing, the indicators of the finished product meet the requirements of the national standard brick No. 150, in line with the national building materials radiological protection standards, which can be widely used in the construction industry.
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