|
Sulfuric acid residue' dissertation">Sulfuric acid residue as an industrial tailings, its contain trace amounts of toxic heavy metals, the potential harm to the environment, but it also contains a large number of iron oxide-based recyclable resources. In this paper, in sulfuric acid burn slag comprehensive utilization of research progress, learn from the experience of extraction of iron oxide tailings iron, environmental protection and resource reuse as a starting point, sulfuric acid residue in iron recycling - strengthening restore acid leaching to provide a new effective way to sulfuric acid residue treatment and utilization. The Hunan smelter sulfur gold concentrate roasting sulfate acid leaching tailings as raw material by XRD, SEM-EDS, ICP test means that the physical and chemical characteristics of the tailings analysis test and found that the raw materials TFe content of 40.25%, accounted for more than 98% and in the the TFe middle Fe3 content, line typical refractory material, direct leaching difficult. Test some of the major research homemade the new sulfide cosolvent used in sulfuric of burning sludge acid leaching iron craft technical conditions and leaching kinetics, and at the same time strengthen the acid-soluble extract low sulfur content of sulfur in the tailings parameter selection. New cosolvent strengthen restore the acid leaching with sulfuric acid solution immersion tests were designed atmospheric pressure reaction under the conditions of the test and orthogonal test, and examines the cosolvent ZnS, 25% Na2S (by 50% and 20% of MnS % CaS, 0.5% Na2S2O3 · 5H2O, 0.5? H3N3S3 mixture) the amount, the amount of sulfuric acid, the initial acid concentration, ratio of liquid to solid, reaction time, reaction temperature, stirring speed and other factors on the leaching effect. The results showed that (1) in the atmospheric acid leaching process, when the additives / slag (g / g) 0.69, sulfuric acid excess factor of 1.4, starting liquid to solid ratio = 2:1, stirring speed 1300r/min, 95 ℃ under reaction 2h, iron Baptist take rate was 89.2%, additives in zinc leaching rate was 89.2%. Significant order for the four main factors that impact on the leaching effect: additives dosage gt; time gt; gt; temperature, the amount of sulfuric acid. SEM and XRD showed significant change in to cinder morphology acid leaching, smaller particle size, reaction orthorhombic sulfur generated. (2) under pressure acid leaching process, when cosolvent excess coefficient 1.1, sulfate excess coefficient 1.4, starting acid concentration of 3.5 mol / L, the reaction temperature is 95 ℃, stirring speed 800r/min, reaction time 3h, iron leaching rate of 99.4%, the cosolvent effective utilization rate of 98.9%. The impact of various factors on the reaction effect significant order: the amount of sulfuric acid gt; time gt; cosolvent dosage gt; temperature. Reduction the leaching kinetics with temperature cinder by studying the sulfuric acid, sulfuric acid concentration, the amount of co-solvent, the relationship of the time, concluded that (1) the leaching process in line with the contraction of the solid film diffusion control nuclear reaction, the reaction model for 1-2 / 3 (X) - (1-X) 2/3 = 92.8e (4078.8T) of t, the leaching rate of formula (DX) / (dt) = (139.2e (-4078.8 / T)) / (1 - ( 1-X) (-1 / 3)). (2) leaching reaction of sulfuric acid apparent reaction order n = 1.2485, the cosolvent apparent reaction order n = .3021. (3) derived from the SEM-EDS analysis burn SiO2 in the slag and sulfur hinder the solid film diffusion. Tailings acid leaching of low sulfur, ammonium sulfide dissolved - sulfur thermal resolution process for sulfur recovery. Analysis of the concentration of ammonium sulfide, liquid-solid ratio, the dissolution temperature, dissolution time, thermal decomposition temperature, the decomposition time for sulfur extraction effect. The results show that: the concentration of 1.17 mol / L, ammonium sulfide liquid to solid ratio of 10 ml / g at 25 ℃ oscillation dissolved 5min at 100 ℃ thermal decomposition 120min sulfur solution leaching rate and precipitation rate reached 97% and 99% respectively above
|