Reaction kinetics of roasting high-titanium slag with concentrated sulfuric acid

A novel method of roasting high-titanium slag with concentrated sulfuric acid was proposed to prepare titanium dioxide, and the roasting kinetics of titania was studied On the basis of roasting process. The effects of roasting temperature, particle size, and acid-to-ore mass ratio on the rate of roasting reaction were investigated. The results showed that the roasting reaction is fitted to a shrinking core model. The results of the kinetic experiment and SEM and EDAX analyses proved that the reaction rate of roasting high-titanium slag with concentrated sulfuric acid is controlled by the internal diffusion on the solid product layer. According to the Arrhenius expression, the apparent activation energy of the roasting reaction is 18.94 kJ/mol.

LiTFSI salt concentration effect to digest lithium polysulfides for high-loading sulfur electrodes

Sulfur utilization improvement and control of dissolved lithium polysulfide(LiPS;Li_(2)S x,2<x≤8)are cru-cial aspects of the development of lithium-sulfur(Li-S)batteries,especially in high-loading sulfur elec-trodes and low electrolyte/sulfur(E/S)ratios.The sluggish reaction in the low E/S ratio induces poor LiPS solubility and unstable Li_(2)S electrodeposition,resulting in limited sulfur utilization,especially under high-loading sulfur electrode.In this study,we report on salt concentration effects that improve sulfur utilization with a high-loading cathode(6 mgs ulfurcm^(-2)),a high sulfur content(80 wt%)and a low E/S ratio(5 m L gs ulfur^(-1)).On the basis of the rapid LiPS dissolving in a low concentration electrolyte,we estab-lished that the quantity of Li_(2)S electrodeposition from a high Li+diffusion coefficient,referring to the reduction of LiPS precipitation,was significantly enhanced by a faster kinetic.These results demonstrate the importance of kinetic factors for the rate capability and cycle life stability of Li-S battery electrolytes through high Li_(2)S deposition under high-loading sulfur electrode.

Flame-retardant concentrated electrolyte enabling a Li F-rich solid electrolyte interface to improve cycle performance of wide-temperature lithium–sulfur batteries

Lithium–sulfur batteries have been regarded as the most promising high-energy electrochemical energy storage device owing to the high energy density, low cost and environmental friendliness. However, traditional lithium–sulfur batteries using ether-based electrolytes often suffer from severe safety risks(i.e. combustion). Herein, we demonstrated a novel kind of flame-retardant concentrated electrolyte(6.5 M lithium bis(trifluoromethylsulphonyl)imide/fluoroethylene carbonate) for highly-safe and widetemperature lithium–sulfur batteries. It was found that such concentrated electrolyte showed superior flame retardancy, high lithium-ion transference number(0.69) and steady lithium plating/stripping behavior(2.5 m Ah cm^(-2) over 3000 h). Moreover, lithium–sulfur batteries using this flame-retardant concentrated electrolyte delivered outstanding cycle performance in a wide range of temperatures(-10 °C, 25 °C and 90 °C). This superior battery performance is mainly attributed to the LiF-rich solid electrolyte interphase formed on lithium metal anode, which can effectively suppress the continuous growth of lithium dendrites. Above-mentioned fascinating characteristics would endow this flame-retardant concentrated electrolyte a very promising candidate for highly-safe and wide-temperature lithium–sulfur batteries.

Experimental Study on Treatment of High-concentrated Sulfur Wastewater by Process of Depositing Natrojarosite and Its Environmental Significance

High-concentrated sulfur wastewater with sodium and COD （chemical oxygen demand） up to 26000 mg/L from a chemical plant, Jiangsu Province of China has been treated by deposition of natrojarosite in lab. The results indicated that the COD of the wastewater was decreased sharply from 26000 mg/L to 1001 mg/L, with removal rate of COD up to 96% by twice precipitations of natrojarosite and twice oxidation of H202. The treated sulfur wastewater reached the requirement of subsequent biochemical treatment to water quality. The optimal operational parameters should be controlled on pH value between 2.50 and 3.20 and 50 g FeCly6H2O solid added in per liter wastewater. The study provided an experimental basis for pretreatment of high-concentrated sulfur wastewater and proposed a new mineralogical method on treatment of other wastewaters. Depositing process of jarosite and its analogs should be able to be used to treat wastewater from mine and other industries to remove S, Fe and other toxic and harmful elements, such as As, Cr, Hg, Pb, etc. in the water.

XPS characteristics of sulfur of bio-oxidized arsenic-bearing gold concentrate and changes of surface nature of bio-oxidation residue

During bio-oxidation of sulfides, the chemical state change of sulfur is a complex and key factor. It is not only an indicator of the extent and intensity of the bio-oxidation, but also controls the property of bio-leaching medium and the period of oxidation. The chemical state of sulfur in sulfides oxidized by leaching bacteria was studied with XPS. Sulfide minerals in the arsenic-bearing gold concentrate consist of pyrite, arsenopyrite, chalcopyrite, galena, sphalerite and so on. In order to probe the pattern of the chemical state change of sulfur in the bio-oxidation residue of arsenic-bearing gold concentrate, the structure of the grains, and the surface nature of the residue, XPS test was carried out through different sputtering duration. The study of XPS clearly shows that: sulfides is progressively oxidized from the surface of minerals to the core by leaching bacteria; the chemical valence of sulfur changes from S2- or [S2]2- to [SO4]2-; sulfur in the core is in a reduction state, S2- or [S2]2-, but exists in an oxidation state S6+ on the surface; due to the chemical state change of sulfur, mineral phase of the bio-oxidation residue is also changed（sulfides inside, while sulfates outside）; the layered structure is found in the grains of the bio-oxidation residue.

Systemic treatment for severe concentrated sulfuric acid burns in an adult male at high altitude:A case report

BACKGROUND The aim of this study was to report a case of a patient who suffered from severe concentrated sulfuric acid burns while working at high altitude.This patient recovered after systemic treatment.We also provide a literature review for a better understanding of the disease.CASE SUMMARY A 30-year-old male,who was working in a local chemical plant in Xining at an altitude of 2261 m,suffered from 85%burns(Ⅲ°70%,deep Ⅱ°15%)after a tank containing 80%concentration of sulfuric acid exploded.The patient immediately received a series of first aid treatments,as well as rigorous wound managements after admission,which included protection for the whole body and organs,prevention and treatment of eye burns,and the appropriate oxygen therapy.After 65 d of treatment,the burn wounds had completely healed,and the patient was transferred to another specialized hospital for further eye treatment.The first aid before admission and the emergency treatment of wounds following admission were appropriate.No severe complications of sepsis,severe renal insufficiency,septic costal chondritis,corneal perforation or other burns occurred during the treatment.CONCLUSION The main causes of concentrated sulfuric acid burns consisted of accidental burns at work,accidents in the outside,factitious injuries and improper laboratory operations.The clinical manifestations were mostly deep Ⅱ°and Ⅲ°burns,with a formation of brown-black,leather-like eschar on the wound surface and locally embolized dendrite-like vessels.The clear cause of the injury and typical clinical manifestations in this case made it easy to diagnosis.However,adult cases with severe concentrated sulfuric acid burns in high altitude areas are rare,so the successful treatment of this case is of great significance.

Pressure acid leaching of zinc sulfide concentrate

Effects of particle size of the zinc sulfide concentrate,leaching temperature,solid-to-liquid ratio and additive amount on pressure acid leaching process of the zinc sulfide concentrate were studied.The results indicate that the additive can improve the reaction kinetics and the conversion rate.And sulfur can be successfully separated from the zinc sulfide concentrate as elemental sulfur.The reasonable experiment parameters are obtained as follows:the leaching temperature 150℃,oxygen partial pressure 1 MPa,additive amount 1%,solid-to-liquid ratio 1:4,leaching time 2 h,initial sulfuric acid concentration 15%,and particle size less than 44μm.Under the optimum conditions,the leaching rate of the zinc can reach 95%and the reduction rate of the sulfur can reach 90%.

Selective leaching of vanadium from V-Ti magnetite concentrates by pellet calcification roasting-H_(2)SO_(4) leaching process

A novel method of pellet calcification roasting-H_(2)SO_(4) leaching was proposed to efficiently separate and extract vanadium(V)from vanadium-titanium(V-Ti)magnetite concentrates.The leaching rate of V is as high as 88.98%,while the leaching rate of impurity iron is only 1.79%.Moreover,the leached pellets can be used as raw materials for blast furnace ironmaking after secondary roasting.X-ray photoelectron spectroscopy(XPS)and scanning electron microscopy with energy dispersive X-ray spectrometry(SEMEDS)analyses showed that V^(3+)was oxidized to V^(5+)after roasting at 1200℃,and V^(5+)was then leached by H_(2)SO_(4).X-ray diffraction(XRD)analyses and single factor experiment revealed a minimal amount of dissolved Fe_(2)O_(3) during H_(2)SO_(4) leaching.Therefore,a high separation degree of V and iron(Fe)from V-Ti magnetite concentrate was achieved through H_(2)SO_(4) leaching.Compared with the traditional roastingleaching process,this process can achieve a high selectivity of V and Fe,and has excellent prospects for industrial production.

Analysis of Sulfur Dioxide Concentration Around Bulk Curing Barn Group

This study was conducted to analyze the spatial distribution of SO2 mass concentration around baking barn groups. A bulk curing barn group was selected as monitoring object, and SO2 concentration around it was monitored for 2 years. The results showed that the SO2 mass concentration within 30-130 m from the baking barn group exceeded the standard, and with the ground as reference, the SO2 mass concentration at the position 0.9-2.1 m from the ground exceeded the stan- dard. According to the limit value of the SO2 mass concentration for sensitive crops, the SO2 mass concentrations over the standard were concentrated within the range of 200-300 m. On the basis of establishment of ＂sulfur control＂, ＂sulfur reduction＂ and ＂sulfur avoiding＂ system, the SO2 emission status of baking barn groups could be improved from the conversion of heat supply method, the utilization of clean en- ergy and adjustment of crop sensitive period and sensitive area.

Quantitative Analysis of the Rate of Geochemical Weathering of Sulfur from Sedimentary Rocks Using Atmospheric Deposition, Concentration and River Discharge Data

Quantitative analysis of the rate of geochemical weathering of sulfur (S) from sedimentary rocks (GeoS) was conducted using concentration (Cs) and discharge (Qs) data from the Tedori River and atmospheric deposition (AtdepS) in the basin. First, S fluxes were calculated using 16 years of Cs and Qs data. The annual average discharge of S (TotalS) was estimated at 8597 ton·year-1 (117.3 kg·ha-1·year-1). Of this, 1331 ton·year-1 was AtdepS (18.2 kg·ha-1·year-1) and another 7266 ton·year-1 was GeoS (99.1 kg·ha-1·year-1). Monthly changes in TotalS were investigated, which showed that GeoS was highest in summer, because of the air temperature, while AtdepS peaked in winter because of seasonal wind. Using Qs and AtdepS corrected for altitude, TotalS, AtdepS and GeoS were estimated at six sites, and among these sites we found that the TotalS per unit area values were random, depending on the site characteristics. In particular, the discharge from the Kuwajima site was remarkably high suggesting that the sedimentary rocks at this site had higher pyrite content than at the other sites. Finally, we also assessed the relationship between the characteristics of sedimentary rocks and GeoS in a range of rivers in the Hokuriku Region, and found that there was a close relationship between concentrations of SO42- greater than 10 mg·l-1 and sedimentary rocks containing the pyrite group. In addition, we estimated that the influence of GeoS was present when the concentration of SO42- in river water was greater than 2 - 3 mg·l-1 in the Hokuriku region.

熟化银精矿氧压强化酸浸行为研究

考虑到浮选银精矿极具回收价值及现有处理工艺存在不足,本文提出了浓硫酸熟化-氧压酸浸的工艺路线。首先,以湿法炼锌过程产出的浮选银精矿为对象,利用浓硫酸的强氧化性破坏浮选残留有机药剂矿物包裹体;其次,利用加压湿法冶金独特的技术优势,氧化溶解低价金属硫化物;最后,重点研究了工艺过程原理及氧压酸浸过程中Zn、Cu、In的浸出行为及浸出渣中物相演变规律。研究结果表明:银精矿颗粒表面残留浮选药剂的P—O、—OH极性基团被浓硫酸氧化破坏,避免产生水化膜及矿物包裹体,促进有价元素的高效浸出;在高温氧化性条件和Fe^(3+)/Fe^(2+)变价离子对的助浸作用下,银精矿物相组成由闪锌矿(Zn S)、锌铁尖晶石(Zn Fe_(2)O_(4))、雌黄铁矿(FeS)、氯化亚铜(Cu Cl)为主,转变为以单质硫(S8)、铁矾(MeFe_(3)(SO_(4))_(2)(OH)_(6),Me:1/2Pb、Na、K)为主,并残留少量的闪锌矿(Zn S);适当提高反应温度和初始质量浓度可促进Zn、Cu、In的浸出,但温度过高会加剧铟铁共沉淀问题,降低锌、铟的浸出率,而质量浓度过高会降低氧气对Zn S及Fe^(2+)的氧化能力,抑制银精矿的溶解;延长反应时间、提高液固比均有利于银精矿的解离浸出;增大氧分压可以加强Fe^(3+)的氧化能力,促进对Zn S及ZnxFe(1-x)S的氧化作用,有利于银精矿的溶解。在反应温度为155℃、初始质量浓度为160 g/L、反应时间为180 min、氧分压为0.8 MPa、液固比为7 m L/g的氧压酸浸条件下,银精矿中Zn、Cu、In的浸出率分别为94.84%、98.36%和91.13%,浸出渣中铅、银的富集率分别达2.88%和7754 g/t。

硫精矿中有价金属铜金银的综合回收利用实验

这是一篇矿物加工工程领域的论文。对某含铜金银硫精矿进行了选矿综合回收实验研究,实验结果表明,采用异丁基黄药+乙硫氮组合捕收剂,氧化钙做抑制剂,2^(#)油做起泡剂,经过一次粗选-三次精选-二次扫选的浮选工艺流程,最终可得到铜品位为16.66%、回收率为86.96%,金品位为278.95 g/t,回收率为75.56%;银品位为1848.74 g/t,回收率为78.55%的精矿产品,有效地实现了硫精矿中铜的综合回收,同时使金、银很好地富集在铜精矿中,便于回收利用,选矿指标理想。

萤石与浓硫酸反应制备氢氟酸动力学研究

为解决采用伴生型萤石代替单一型萤石生产氢氟酸的技术难题,揭示了伴生型萤石与浓硫酸的反应机制及动力学规律。研究在不同液固摩尔比和温度条件下单一型萤石和伴生型萤石与浓硫酸反应生成氟化氢的转化率。结果表明,单一型萤石产酸的最佳液固摩尔比和温度分别为1.25∶1和200℃,转化率为97.5%;伴生型萤石为1.50∶1和200℃,转化率为84.5%。单一型萤石产酸反应符合界面化学反应控制模型,而伴生型萤石产酸反应符合固相产物层内扩散控制模型。扫描电镜(SEM)结果表明,伴生型萤石与浓硫酸反应时存在严重的团聚现象并形成致密的硫酸钙钝化层,阻碍了浓硫酸与未反应萤石内核的接触。本试验为伴生型萤石与浓硫酸反应生产无水氢氟酸提供了科学依据。

硫化锌精矿氧压浸出过程中硫回收率的影响机制

锌氧压浸出特点是硫化锌精矿直接湿法浸出,硫不进入烟气,而是直接转化成单质硫回收。该工艺生产流程更简单,环境友好,综合能耗低,硫磺产品相对更容易储存、运输及销售。因此该技术的推广应用对锌冶炼行业节能减排乃至碳达峰碳中和目标的实现意义重大。从精矿矿物特征及金属的浸出率、浸出过程中硫元素的酸化率、硫磺结晶过程控制、硫浮选效率以及硫精矿热过滤温度等方面着手,研究其对硫磺回收率的影响机制。

某选硫尾矿回收明矾石和石英试验研究

为充分有效地回收尾矿中的明矾石和石英,针对尾矿中硫含量高、SiO_(2)含量低、明矾石和地开石含量较高的特点,开展了尾矿脱硫回收明矾石和石英的试验研究。试验考察了脱硫浮选碳酸钠、油酸、水玻璃等药剂以及明矾石和石英混浮、脱硫再选工艺等对明矾石和石英回收的影响。结果表明,碳酸钠用量为3000 g/t、油酸用量为250 g/t~300 g/t、水玻璃用量为100 g/t~200 g/t、经两次粗选可得到SiO_(2)品位74.66%、TS 0.99%的尾砂,三次粗选可得SiO_(2)品位79.77%、TS0.87%的尾砂精矿;三次粗选精矿合并精选时,随着精选水玻璃用量的增加,S在精矿中得到富集。综合考虑,两次精选均为空白精选,可获得品位27.59%的明矾石精矿。

磷酸酯基阻燃电解液用于高安全锂硫电池

Li–S电池被认为是最有希望的下一代高能量密度二次电池之一,开发高效阻燃电解液对于提升电池安全性极为重要.本文对高浓度磷酸三乙酯(TEP)和磷酸三(2,2,2-三氟乙基)酯(TFP)电解液在锂–硫化聚丙烯腈(Li–PAN/S)电池中的应用展开了深入研究,以同样的锂盐摩尔比和氟代醚稀释梯度,研究了TEP和TFP基局部高浓度电解液对锂金属负极和硫正极稳定性的影响,详细解析了两种溶剂分子在电池循环过程中的界面反应.研究表明,磷酸酯基高浓度电解液在Li–PAN/S电池中展示了较优异的循环稳定性,通过优化TTE的稀释比例,提升了电池的倍率特性.对比基于TEP和TFP的电解液,发现TEP基电解液具有更好的锂沉积/剥离性能,而TFP基电解液在界面生成更多的有机组分,导致不稳定的界面膜.以TEP212为电解液的锂硫电池能够在1C的倍率下稳定循环200圈以上,放电比容量保持在1080.8 mA·h·g-1.

锌氧压酸浸硫精矿和硫尾矿的矿物学特征与环境活性

采用电感耦合(ICP-OES)、X射线衍射(XRD)、扫面电镜-能谱(SEM-EDS)、红外光谱(FTIR)及差热差重(TG-DTA)等多种检测方法对锌氧压酸浸硫精矿和硫尾矿的化学组成、粒度分布、物相结构等进行研究,并采用毒性浸出程序(TCLP)法考察其短期环境活性。研究结果表明:硫精矿1和硫精矿2主要以球状的单质硫存在,其中,少量硫精矿1以小颗粒的闪锌矿、黄铁矿等附着于块状的铁矾颗粒上,平均粒径为22.1μm;少量硫精矿2以块状的闪锌矿、黄铁矿和小颗粒存在,平均粒径为59.2μm。2种硫精矿在185~340℃时会剧烈燃烧,热稳定性较差。2种硫尾矿主要以块状的铅黄铁矾和黄钠铁矾存在,其中,硫尾矿1平均粒径为21.1μm;硫尾矿2含一定的赤铁矿(16.86%),平均粒径为5.3μm。硫精矿和硫尾矿中锌和镉元素在弱酸条件下不稳定,硫尾矿1中锌和镉的浸出量分别超标1.93倍和2.50倍;硫精矿2的分别超标2.03倍和6.56倍,硫尾矿1的分别超标3.46倍和5.94倍,硫尾矿2的分别超标11.10倍和8.28倍。

Separation and enrichment of elemental sulfur and mercury from hydrometallurgical zinc residue using sodium sulfide

The separation and enrichment of mercury and the recovery of elemental sulfur from flotation sulfur concentrate in zinc pressure leaching process were carried out by sodium sulfide leaching and carbon dioxide precipitating. The results show that the leaching rate of elemental sulfur is more than 98%, and 98.13% of mercury is enriched in the residue, under the optimized conditions of sodium sulfide concentration 1.5 mol/L, liquid/solid ratio 6：1 and leaching time 30 min at room temperature. In addition, the content of mercury is enriched 5.23 times that in the leaching residue. The elemental sulfur is precipitated from leaching solution under conditions of carbon dioxide flow rate 200 mL/min and blowing time 150 min, while solution is stirred adequately. The recovery efficiency of elemental sulfur reaches 97.67%, and the purity of elemental sulfur is 99.75%, meeting the requirements of industrial first-rate product standard according to the national standard of GB/T 2449-2006 （PRC）.

云南某贫细硫化铜矿石选矿工艺优化研究

云南某低品位细粒嵌布的铜矿石铜、硫品位分别为0.161%和9.704%,有价铜矿物嵌布粒度细,铜硫分离富集难度较大。为实现该硫化铜矿石资源的高效开发利用,在选厂原选矿流程及原矿工艺矿物学研究基础上,进行了系统的磨浮试验。结果表明:矿石采用磨矿—1粗2扫铜硫混合浮选—混浮粗精矿再磨—1粗3精2扫铜硫分离浮选闭路流程处理,可获得铜品位14.69%、铜回收率63.15%的铜精矿,硫品位29.16%、硫回收率75.10%的硫精矿,试验铜精矿品位较现场提高近3个百分点,铜回收率提高15个百分点以上,显著优于现场生产指标,达到了理想的综合回收铜硫效果。研究结果可作为工艺流程优化的依据。

气相色谱法测定坚果中16种有机氯、拟除虫菊酯类农药残留量

建立气相色谱法(gas chromatography,GC)检测坚果中16种有机氯、拟除虫菊酯类农药残留的分析方法。样品通过丙酮:正己烷(3:7,V:V)提取,0.2 mL浓硫酸磺化净化,有机氯和拟除虫菊酯经DB-17MS色谱柱(30 m×0.32 mm,0.25μm)分离,气相色谱-电子捕获检测器(gas chromatography-electron capture detector,GCECD)定量检测。有机氯、拟除虫菊酯类农药在0.01~0.20μg/mL浓度范围内与对应的峰面积呈现良好的线性关系,决定系数(r2)均在0.996以上,方法检出限为0.1~0.4μg/kg;分别对不同基质(开心果、澳洲坚果、腰果、碧根果、核桃、巴旦木)样品进行低(10μg/kg)、中(40μg/kg)、高(100μg/kg)3个浓度加标提取率实验,提取率范围为81.6%~119.5%,相对标准偏差(relative standard deviation,RSDs)为1.03%~5.36%。本方法分析简单、准确度高、重复性好,适用于坚果中16种有机氯、拟除虫菊酯类农药残留的测定。