Extraction Of Feldspar And Quartz In Tailings And Recycling Of Beneficiation Wastewater

As piling of a great quantity of tailings leads to occupation of land, environmental pollution and waste of resources, comprehensive utilization of tailings as "secondary raw materials" accords with the objective of building a resource-conserving and environment-friendly society in China. Iron beneficiation tailings contain 20.958% of Fe2O3. 7.239% of Na2O and 63.354% of SiO2. And iron concentrates, feldspar concentrates and quartz concentrates can be recycled in the following process:strong magnetic flotation of iron-flotation of feldspar - reverse flotation of quartz. However, there is great water consumption in such processes, resulting in a waste of resources. In this study, the water used in each test is subject to centralized collection, treatment and reutilization. Part of the residual fine silt in the test is mixed with sludge from waterworks in certain proportion and then used for clover planting. Along with the increasing of planting times, the microorganisms in the reclaimed soil also increase. In this study, iron beneficiation tailings in a steelworks is taken as the research object, and experimental research on extraction of iron, feldspar and quartz in trailing is performed using the process of "iron tailing classification of coarse ores and fine ores-strong magnetic separation-reverse flotation of iron from strong magnetic fine ores-flotation of feldspar from strong magnetic tailings-reverse flotation of quartz from feldspar tailings". It shows that the mixture of fine mud and sewage sludge can reach the goal of reclamation(1) In case of 45% MOG-0.038mm, the ores undergo two phases of strong magnetic concentration respectively under the magnetic field intensity of 11.000Gs and 5,000Gs. NaOH is used as the regulator, quick lime is used as the activator, starch is used as the depressor, and saponified oleic acid is used as the collector. Iron concentrators are obtained after one roughing process and four scavenging processes, with an iron concentrate grade of 65.75% and a recycling rate of 51.42%.(2) In the test of feldspar flotation, in times of 4.5min grinding, the degree of mineral liberation of soda feldspar reaches 94%, the particle size distribution d0.1 is 18.477?m, d0.5 is 81.257?m, and d0.9 is 268.511?m. After sedimentation and desliming,37% hydrochloric acid (300g/t) is used for impurity removal in flotation, the pH value is adjusted to 5-6. saponified oleic acid (referred to as "A") and mersolates (referred to as "B") are used as collectors, and the A+B mixed collector is used for impurity removal roughing and scavenging. Hydrofluoric acid (HF)+hydrochloric acid (HCl) is used as the regulator, the pH value is 2-3, and the mixed amine collector (referred to as "Sa") is used for feldspar flotation. At last, feldspar concentrates with a Na20 grade of 10.83% and a recycling rate of 72.58% are obtained to meet the industrial standards for Grade One ores.(3) Reverse flotation of quartz from tailings from feldspar flotation is tested. Quartz concentrates at a grade of 99.31% are obtained after flotation consisting of one roughing process and five scavenging processes. As a result of classification of quartz concentrates, the grade of +0.074mm SiO2 is 95.60%, and that of -0.074mm SiO2 is 99.43%. When acid leaching tests are performed respectively for such concentrates, the +0.074mm SiO2 can reach the standards for acid leached quartz sand (SiO2 99.6%), and the -0.074um SiO2 can nearly reach the standards for high-purity quartz powder (SiO2 99.93%).(4) After centralized recycling of wastewater produced in the test, such wastewater is tested. Among the testing items, the heavy metal in the beneficiation wastewater does not exceed relevant emission standards, but such indicators as pH value, CODcr and F-1 exceed relevant emission standards. Reutilization of such wastewater in the beneficiation process could adversely impact the beneficiation performance. In this test, lime is used to remove the F-1. When 1.4g/L of lime is used, the F-1 concentration in the wastewater will meet the requirements specified in the Integrated Wastewater Discharge Standard. High-efficiency flocculant PAFC is used to remove the suspended substances, COD and heavy metal in the wastewater after the treatment using quick lime and to further remove the F-1. When 150mg/L of PAFC is used, the treated water will meet relevant national discharge standards in all aspects except COD. Then chlorine dioxide, a high-efficiency green oxidant, is used to further remove COD in the wastewater. When 15mg/L of chlorine dioxide is used, the treated water will meet relevant national discharge standards in all aspects.(5) Fine silt and sludge from waterworks are mixed in an appropriate ratio to form reclaimed soil. Clover is planted continuously in such soil, and the total amount of microorganisms in the soil reaches 350.7×105cfu·g-1, which is 30.36% of the amount in the original soil. The bacteria, actinomyces and epiphytes in the reclaimed soil respectively increase to 347.11×105cfu·g-1,3.01×105cfu·g-1 and 0.58x105cfu·g-1 by 394.74%,393.44% and 728.57%.