A novel process for Fe recovery and Zn, Pb removal from a low-grade pyrite cinder with high Zn and Pb contents

Comprehensive utilization of pyrite cinders is increasingly important because of their huge annual outputs and potential valuable metals recovery to cope with the gradual depletion of high-grade mineral resources. In this work, a new process, i.e., a high-temperature chlorination–magnetizing roasting–magnetic separation process, was proposed for recovering Fe and removing Zn, Pb from a low-grade pyrite cinder containing 49.90 wt% Fe, 1.23 wt% Zn, and 0.29 wt% Pb. Various parameters, including the chlorinating conditions(dosage of Ca Cl2, temperature, and time) and the magnetization roasting conditions(amount of coal, temperature, and time) were investigated. The results indicate that the proposed process is effective for Fe recovery and Zn, Pb removal from the pyrite cinder. Through this process, 97.06% Zn, 96.82% Pb, and approximately 90% S can be removed, and 89.74% Fe is recovered as magnetite into the final product under optimal conditions. A purified magnetite concentrate containing 63.07 wt% Fe, 0.16 wt% P, 0.26 wt% S, and trace amounts of nonferrous metals(0.005 wt% Cu, 0.013 wt% Pb, and 0.051 wt% Zn) was obtained. The concentrate can be potentially used as a high-quality feed material for producing oxidized pellets by blending with other high-grade iron ore concentrates.

Utilization of gold-bearing and iron-rich pyrite cinder via a chlorination–volatilization process

The chlorination-volatilization process has been adopted to make full use of gold-bearing and iron-rich pyrite cinder. However, problems of low recovery rate, pulverization of pellets, and ring formation have been encountered during the industrialization of this process. The effects of various parameters on the volatilization rates of valuable metals and on the compressive strength of roasted pellets were investigated in this paper. The parameters include the CaCl_2 dosage, heating temperature, and holding time. The results show that heating temperature is the most important parameter for the recovery of target metals. More CaCl_2 was needed for the recovery of zinc than for the recovery of gold, silver, and lead. CaCl_2 started to react with sulfides/SO_2/SiO_2 at temperatures below the melting point of CaCl_2 to generate Cl_2/HCl. Gaseous CaCl_2 was formed at higher temperatures and could react with any of the components. The compressive strength of roasted CaCl_2-bearing pellets first decreased slowly with increasing temperature at temperatures lower than 873 K, which could result in the pulverization of pellets during heating. Their compressive strength increased dramatically with increasing temperature at temperatures greater than 1273 K. Certain quantities of CaCl_2 and Fe(Ⅱ) could improve the compressive strength of the roasted pellets; however, the addition of excessive CaCl_2 decreased the compressive strength of pellets.

Speciation analysis of metals (Tl,Cd and Pb) in Tl-containing pyrite and its cinder from Yunfu Mine,China,by ICP-MS with sequential extraction

The speciation of heavy metals such as thallium,cadmium and lead existing in pyrite and pyrite cinder was analyzed by ICP-MS with a sequential extraction procedure.The distribution patterns of these metals including exchangeable,reducible,oxidizable and residual fractions were obtained.Tl,Cd and Pb in pyrite and pyrite cinder samples from each extraction step were determined by inductively coupled plasma mass spectrometry(ICP-MS).Under the optimized instrumental conditions,detection limits of Tl,Cd and Pb in different matrices were within the range of 0.006-0.07 μg/L,and the relative standard deviations ranged from 0.8% to 1.2%.The accuracy of Tl,Cd and Pb determination was checked by analyzing two certified reference materials.The results demonstrate that trace Tl,Cd and Pb in the samples can be accurately determined.The sequential extraction results revealed that the percent contents of Tl,Cd and Pb in exchangeable,reducible and oxidizable fractions in pyrite cinder are different from those in pyrite and in pyrite cinder.Tl,Cd and Pb mostly are distributed in residual fraction.Therefore,the mobility of metals in pyrite is higher than that in pyrite cinder.Although distributions of Tl,Cd and Pb in the non-residual fraction are not dominant in pyrite cinder,the total concentrations of them could not be ignored.Consequently,attention must be paid to the risk of potential pollution by pyrite cinder.

Preparation of pre-reduced pellet using pyrite cinder containing nonferrous metals with high temperature chloridizingreduction roasting technology—Effect of CaCl_2 additive

The role of CaCl2 during the high temperature chloridizing-reduction roasting process was investigated, aiming at acquiring high strength blast furnace burden with high iron grade and low nonferrous metals content. The effects of CaCl2 dosage on pelletizing, preheating and reduction were investigated. The results show that CaCl2 can improve the wet drop strength but reduces the thermostability of pyrite cinder green balls. When the dosage of CaCl2 exceeds 1%, the compressive strength of preheated pellets decreases while the growth of iron oxide particles is improved. Furthermore, the compressive strength of pre-reduced pellets increases but the metallization degree of pre-reduced pellets decreases with CaCl2 additive. The removal tests indicate that Zn can be removed completely without CaCl2 additive, Cu is removed only under the condition with CaCl2 additive and part of Pb must be removed by CaCl2 additive.

Preparation of solid polyferric sulfate from pyrite cinders and its structure feature

Acid leaching solution was obtained after mixing pyrite cinders with H 2SO 4, then heating the mixture of pyrite cinders and H 2SO 4 at 200300 ℃, leaching the heated mixture with water and filtrating. Polyferric sulfate (PFS) solution was produced by adding suitable amounts of FeSO 4·7H 2O and NaClO 3 into acid leaching solution. By concentrating and drying PFS solution, solid PFS with alkali degree of 6.40%22.4% was prepared. Fe 4.67 (SO 4) 6(OH) 2·20H 2O in the solid PFS was discovered by XRD analysis. FT IR spectroscopy shows that the absorption peaks at 3 400 cm -1 and 1 635 cm -1 arise from OH and absorption peaks at 998 cm -1 and 669 cm -1 come from Fe-OH in the solid PFS.

Hexagonal hematite platelets synthesized from pyrite cinders by hydrothermal process

Well-crystallized hexagonal hematite (α-Fe2O3) platelets were synthesized by hydrothermal process,using a highly concentrated ferric hydroxide as precursor.The precursor was prepared by adding ammonia to the ferric sulfate solution which was obtained by leaching pyrite cinders with sulfuric acid.Structure and morphology of the synthesized products were investigated by X-ray diffraction,scanning electron microscope,transmission electron microscope and selected area electron diffraction.The results reveal that the reaction temperature has significant effects on the structure,size and shape of the synthesized hematite particles.Typical hexagonal hematite platelets,about 0.4?0.6 μm in diameter and 0.1 μm in thickness,were prepared at 230 °C for 0.5 h.Al3+,contained in the sulfuric acid leaching solution as an impurity,plays an extremely important role in the formation of hexagonal hematite.In addition,a possible mechanism about the formation of hexagonal hematite platelets was proposed.

Comparisons of species and coagulation effects of PFS solution and solid PFS from pyrite cinders

Pyrite cinder is a kind of solid waste of sulfuric acid industry. After mixing pyrite cinders with sulfuric acid, ferric sulfate was obtained by heating, maturing, dissolving and filtrating. Suitable amounts of FeSO 4·7H 2O and NaClO 3 were added into ferric sulfate solution and polyferric sulfate(PFS) solution was produced. Solid PFS was made by concentrating and drying PFS solution. Time-dependent complex colorimetric tests were done while ferron agent reacted with Fe 3+ in the solution. The results show that the proportion of transitional low polymeric species and high polymeric species are increased after PFS solution is transferred into solid PFS. It was discovered by jar tests that solid PFS has very good coagulation effects relevant to the increase of transitional lower polymeric species.

Micaceous iron oxide prepared from pyrite cinders by hydrothermal method

Micaceous iron oxide(MIO) with a hexagonal flaky shape was prepared by hydrothermal method.The ferric hydroxide used as precursor was obtained by an acidic leaching solution of pyrite cinders reacting with ammonia solution.The optimal experimental conditions for preparing micaceous iron oxide were investigated by orthogonal experiments.Micaceous iron oxide can be successfully prepared when optimal parameters of total iron concentration of 2.0 mol/L,pH value of 8,n(Fe2+)/n(Fe3+) of 0.1,mass of seed crystal of 1 g,reaction temperature of 260 °C and reaction time of 30 min are applied.X-ray diffractometry(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM) and selected area electron diffractometry(SAEM) were adopted to characterize the hydrothermal products prepared under optimal conditions.The results indicate that highly crystallized α-Fe2O3 hexagonal flakes,about 1.0-1.5 μm in diameter and 0.1 μm in thickness,are prepared.Furthermore,the quality of micaceous iron oxide prepared can meet the required characteristics of micaceous iron oxide pigments for paints(ISO10601-2007).

Effect of supports on the redox performance of pyrite cinder in chemical looping combustion

Chemical looping combustion(CLC)is a clean and efficient flame-free combustion technology,which combust the fuels by lattice oxygen from a solid oxygen carrier with inherent CO_(2)capture.The development of oxygen carriers with low cost and high redox performance is crucial to the whole efficiency of CLC process.As the solid by-product from the sulfuric acid production,pyrite cinder presented excellent redox performance as an oxygen carrier in CLC process.The main components in pyrite cinder are Fe_(2)O_(3),CaSO_(4),Al_(2)O_(3)and SiO_(2)in which Fe_(2)O_(3)is the active component to provide lattice oxygen.In order to systematic investigate the functions of supports(CaSO_4,Al_(2)O_(3)and SiO_(2))in pyrite cinder,three oxygen carriers(Fe_(2)O_(3)-CaSO_(4),Fe_(2)O_(3)-Al_(2)O_(3)and Fe_(2)O_(3)-SiO_(2))were prepared and evaluated in this study.The results showed that Fe_(2)O_(3)-CaSO_(4) displayed high redox activity and cycling stability in the multiple redox cycles.However,both Fe_(2)O_(3)-Al_(2)O_(3)and Fe_(2)O_(3)-SiO_(2)experienced serious deactivation during redox reactions.It indicated that the inert Fe-Si solid solution(Fe_(2)SiO_(4))was formed in the spent Fe_(2)O_(3)-SiO_(2)sample,which decreased the oxygen carrying capacity of this sample.The XPS results showed that the oxygen species on the surface of Fe_(2)O_(3)-CaSO_(4) could be fully recovered after the 20 redox cycles.It can be concluded that CaSO_(4) is the key to the high redox activity and cycling stability of pyrite cinder.

Investigation of the redox performance of pyrite cinder calcined at different temperature in chemical looping combustion

As an industrial solid waste,pyrite cinder exhibited excellent reactivity and cycle stability in chemical looping combustion.Prior to the experiment,oxygen carriers often experienced a high temperature calcination process to stabilize the physico-chemical properties,which presented significant influence on the redox performance of oxygen carriers.However,the effect of calcination temperature on the cyclic reaction performance of pyrite cinder has not been studied in detail.In this work,the effect of calcination temperature on the redox activity and attrition characteristic of pyrite cinder were studied in a fluidizedbed reactor using CH_(4) as fuel.A series of pyrite cinder samples were prepared by controlling the calcination temperature.The redox activity and attrition rate of the obtained pyrite cinder samples were investigated deeply.The results showed that calcination temperature displayed significant impact on the redox performance of pyrite cinder.Considering CH_(4) conversion(80%–85%)and attrition resistance,the pyrite cinder calcined at 1050℃ presented excellent redox properties.In the whole experiment process,the CO_(2) selectivity of the pyrite cinder samples were not affected by the calcination temperature and were still close to 100%.The results can provide reference for optimizing the calcination temperature of pyrite cinder during chemical looping process.

Research on Kaolinite Type Pyrite Slag as Activity of Cement Mixed Material

Produced by the production of sulfuric acid from kaolinite type when the Fe2O3 and metakaolin together constitute the kaolinite type pyrite cinder is a typical industrial solid waste. Only in southern Sichuan China storage capacity has reached millions of tons, that caused serious impact on ecology and environment in this area. It also caused serious waste of resources. The magnetite concentrate and given priority to with partial kaolinite pyrite cinder tailings that were obtained by grinding and magnetic separation. This experiment studied the relationship composition and particle size with its activity when cinder tailings as cement mixed material. The results show that the particle size of D90 were 88 micron, 56 micron, 40 micron, the activity index were 1.036, 1.068, 1.102. The slag after magnetic separation is a kind of very good activity of cement mixed material. It can make good use of the industrial solid waste.

黄铁矿烧渣水洗液中Cu^(2+)和Au的综合回收试验分析

云南某黄金冶炼厂黄铁矿烧渣水洗液日产量大,含有价的Au和Cu^(2+),采用铁粉置换联合微孔截金的新工艺回收水洗液中的Cu^(2+)和Au,具有巨大的经济价值和环境效益。本文研究了铁粉置换时p H值、铁粉用量和置换时间等因素对Cu^(2+)、Au回收率的影响,探究了在微孔过滤中微孔粒径的大小(2μm、1μm、<1μm)对颗粒金回收的影响。试验结果表明p H值为3、铁粉用量6 g/L、反应时间2.5 h的条件下,水洗液中Cu^(2+)的置换率达到98.88%,置换效果较好,微孔粒径<1μm时,金的回收率达到99.47%。铁粉置换联合微孔截金新工艺对Cu^(2+)和Au的回收率较高,具有物料消耗小、成本低等优点,经济效益明显。

硫铁矿烧渣资源化利用研究与展望

硫铁矿烧渣是硫酸生产过程中产生的一种废渣,属于化工废渣的一种,分布较广且排量大,绝大部分都以固废形式进行堆放,造成了一定的污染,危害农业及人体健康。但因其成分中还含有一定量的三氧化二铁及三氧化二铝等可回收利用的资源,无论从固废处置角度还是从资源回收的角度来讲,硫铁矿烧渣的资源化利用都具备一定的价值,本文从硫铁矿烧渣的产量及利用途径等方面介绍硫铁矿烧渣资源化利用的现状和未来展望。

Intensified bioleaching of low-grade molybdenite concentrate by ferrous sulfate and pyrite

Intensifying effects of ferrous sulfate and pyrite on bioleaching of low-grade molybdenite concentrate were studied in this paper. The experimental results show that the oxidation dissolution of molybdenite can be accelerated with the addition of either ferrous sulfate or pyrite in bi- oleaching medium. Pyrite has better enhancing effect than ferrous sulfate, and the highest molybdenum leaching rate in pyrite-added solutions is 20.85 %, increasing by 12.64 % compared with that in 9 K leaching system. Molybdenum leaching rate does not increase linearly with the increase of the addition of either ferrous sulfate or pyrite in each type solution. Great amounts of [NH4Fe3（SO4）2（OH）6] and [KFe3（SO4）2（OH）6] with different morphologies will be deposited on molybdenite ores when the additions of Fe from ferrous sulfate or pyrite exceed that from 9 K leaching system by 0.5 times, and these deposits hinder the oxidation dissolution of molybdenite to some extent.

磷石膏-硫酸渣煤基还原焙烧物相转化研究

还原分解是磷石膏综合利用途径之一,但分解温度高、能耗高阻碍了该方法的应用。铁基添加剂有助于降低磷石膏还原分解温度,提高磷石膏分解效率。通过热力学分析、X射线衍射(XRD)仪,研究硫酸渣为铁基添加剂,磷石膏-硫酸渣在煤基条件下同步还原焙烧的物相转化。结果表明,当磷石膏、硫酸渣和煤粉配比为30∶10∶1混合还原焙烧,温度为700~900℃时,硫酸渣可以实现磁化还原生成Fe_(3)O_(4),其中800℃时,磁选可获得铁品位和回收率分别为48.33%和32.31%的磁铁矿;温度为1000~1100℃时,硫酸渣难以发生同步还原,主要以Fe_(2)O_(3)和FeS存在。磷石膏在700~1100℃范围内逐渐分解,部分CaSO4转为Ca_(5)(PO_(4))_(3)F;当温度大于1000℃后,开始转化为CaS和Ca_(5)(PO_(4))_(3)OH。研究发现,磷石膏中杂质P和F的存在,以及分解温度对磷石膏-硫酸渣在煤基条件下的同步还原分解影响较大。本研究可为磷石膏、硫酸渣同步利用提供理论参考。

不同工艺条件对深度还原—磁选某硫酸渣的影响

针对河北某硫酸渣进行了深度还原—磁选工艺研究,系统研究了影响硫酸渣深度还原工艺和选别工艺的因素对还原铁精矿品位、回收率及硫含量的影响,并结合扫描电镜(SEM)、X射线衍射(XRD)等手段对硫酸渣原矿、焙烧产物及铁精矿进行分析测试。结果表明,硫酸渣中黄铁矿与脱硫剂发生反应,生成金属铁和硫化钙;在最佳深度还原工艺条件下,仅采用一段磨矿—磁选工艺,就可获得铁精矿品位93.13%、回收率92.21%、硫的含量0.06%的还原铁精矿,并经过后续处理可直接用于炼钢,达到高效利用固体废弃物硫酸渣的目标。

硫铁矿烧渣资源化利用研究进展

硫铁矿烧渣是制酸工业产生的固体废弃物,其大量堆存不仅破坏了生态环境,还浪费了其中的宝贵资源。烧渣的“再利用、再循环、减量化”(3R)技术和方法对其综合利用至关重要。从原料化和材料化两个方面综述了烧渣资源化利用研究现状。烧渣原料化主要是指回收其中的铁、铜、铅、锌、钴、银、金等有价金属;而材料化主要是指利用其中的铁和铝硅酸盐等组分制备功能性材料,如建筑材料和化工材料等。提铁降杂和有价元素的综合回收以及多用途、再循环功能性材料的研发是未来硫铁矿烧渣资源化利用研究的重点方向。

低品位硫铁矿烧渣生产复合硅酸盐水泥工艺优化

这是一篇矿物材料领域的论文。为因地制宜寻求低品位硫铁矿烧渣的综合利用途径,解决硫铁矿烧渣大量堆存的问题,并缓解土壤及水质污染,进行了低品位硫铁矿烧渣生产复合硅酸盐水泥工艺优化研究。利用硫铁矿烧渣具有铁含量高的特点,作为外加剂,将其掺入水泥熟料、脱硫石膏、粉煤灰等,混合磨细,制备复合硅酸盐水泥,以强度为指标,确定适宜的硫铁矿烧渣掺量。通过对不同硫铁矿烧渣掺量制备的水泥试块进行物理性能检测,利用正交实验对工艺条件进行优化。结果表明,较佳工艺条件为,水泥熟料掺量为55%,钙硅比为2.5,灰渣比为1,水灰比为0.4,在此条件下,实验制得的水泥28 d抗压强度为43.9 MPa,强度等级为42.5。

Process Optimization and Reaction Mechanism of Removing Copper From an Fe-Rich Pyrite Cinder Using Chlorination Roasting

The aim is to remove copper from a pyrite cinder by optimizing the chlorination roasting process using re-sponse surface methodology （RSM） and the reaction mechanism of chlorination roasting based on thermodynamic calculation was discussed. A quadratic model was suggested by RSM to correlate the key parameters, namely, dos-age of chlorinating agent, roasting temperature and roasting time to the copper volatilization ratio. The results indi- cate that the model is well consistent with the experimental data at a correlation coefficient （R2） of 0.95, and the dosage of chlorinating agent and roasting temperature both have significant effects on the copper volatilization ratio. However, a roasting temperature exceeding 1170 ~C decreases the volatilization ratio. The optimum conditions for removing copper from the cinder were identified as chlorinating agent dosage at 5%, roasting temperature at i155.10 ℃ and roasting time of 10 min; under Such a conditiom a copper volatilization ratid of 95.16% Was a- chieved from the cinder. Thermodynamic calculation shows that SiO2 in the pellet plays a key role in the chlorine re-lease from calcium chloride, and the chlorine release reactions cannot occur without it.

Reduction of Pyrite Cinder Pellets Mixed with Coal Powder

Direct reduction of pyrite cinder in a rotary hearth furnace （RHF） was studied under the condition of labo ratory simulation. Effects of reduction temperature, reduction time, molar ratio of carbon to oxygen, .and CaO addition on metallization rate as well as compressive strength of the pellets after reduction were discussed. The results showed that the metallization rate and compressive strength were 93.9% and 2 160 N per pellet respectively under the conditions of the reduction temperature of 1 200 ℃, the reduction time of 16 min, and the molar ratio of carbon to oxygen （xc/xo） of 1. 0; adding 2.5% CaO was beneficial to sulfur enrichment in slag phase of pellet, and metal- lization rate increased slightly while compressive strength decreased.