Ultrasound effects on zinc recovery from EAF dust by sulfuric acid leaching

In this work, an ultrasound-assisted leaching process was studied for the recovery of zinc from electric arc furnace （EAF） dust, in which zinc was mainly present in the form of franklinite （60%）. HydrometaUurgy is emerging as a preferred process for the recovery of a va- riety of metals, and the use of ultrasound could offer advantages over the conventional leaching process, especially for the dissolution of franklinite. Franklinite is a refractory phase that is difficult to leach and represents the main obstacle in conventional hydrometallurgy proc- essing. Atmospheric leaching with different sulfuric acid concentrations （0.2-2.0 M） at two temperatures （323 and 353 K） was performed. The tests were conducted using both conventional and ultrasound-assisted leaching. After the leaching tests, the solid residues were charac- terized by scanning electron microscopy （SEM） and X-ray diffraction （XRD） techniques, whereas the leach liquor was analyzed by induc- tively coupled plasma spectroscopy OCP）. The use of ultrasound facilitated the dissolution of franklinite at low acid concentrations and re- suited in a greater zinc recovery under all of the investigated operating conditions.

Recovery of antimony from antimony-bearing dusts through reduction roasting process under CO–CO_2 mixture gas atmosphere after firstly oxidation roasted

This paper mainly investigated the antimony recovery from antimony-bearing dusts through reduction roasting process after the dust firstly oxidation roasted.CO–CO2 mixture gas was used as reducing agent,and the antimony-containing phase was reduced into Sb4O6,volatilized into smoke,and finally recovered through the cooling cylinder.The antimony recovery rate increased from 66.00 wt%to 73.81 wt%in temperature range of 650 to 800°C,and decreased with temperature increased further to 900°C due to the reduction of Sb4O6 to the nonvolatile Sb.Similarly,the CO partial pressure also played a double role in this test.Under optimized conditions of roasting temperature of 800°C,CO partial pressure of 7.5 vol%and roasting time of 120 min,98.40 wt%of arsenic removal rate and 80.40 wt%antimony recovery rate could be obtained.In addition,the“As2O3”product could be used for preparing ferric arsenate which realized the harmless treatment of it.

Preparation of potassium salt with joint production of spherical calcium carbonate from sintering dust

Several physical and chemical detection methods were used to study the basic properties of sintering dust （ESP dust） collected from Baogang Steel Corporation. The result shows that the major constituents of the ESP dust are KCl, NaCl, Fe2O_3 and Fe3O_4. Water leaching experiment on the sintering dust shows that KCl in the ESP dust can be separated and recovered by water leaching and fractional crystallization. Component analysis of leaching solution indicates that the massive calcium sulfate in the leaching solution should be removed first in order to obtain the pure potassium salt. In order to provide theoretical guidance to inhibit the dissolution of calcium ions from the sintering dust, the water leaching experiment of ESP dust and the dissolution behavior of CaSO_4 in the potassium chloride, sodium chloride, potassium sulfate and their mixed salt solution were studied. It is found that, a lower liquid-solid ratio should be chosen in the leaching process to inhibit the dissolution of calcium sulfate dehydrate. Using sodium carbonate solution as a precipitating agent, the influences of the concentration of sodium carbonate solution, reaction temperature, stirring speed and equilibrium time on the preparation of the spherical calcium carbonate were studied. Spherical calcium carbonate with good dispersing performance and grain size distribution in nanometer range of less than 10 μm was obtained. Furthermore, a potassium recovery process with joint production of spherical calcium carbonate was designed. This process is technically viable and considerable in economic benefit.

Reduction of chromium oxides in stainless steel dust

The recovery of metal oxides from stainless steel dust using C（graphite）, SiFe, and Al as reductants was investigated under various conditions. The apparent distribution ratio of Cr（L Cr ′^m/s ） in the recovered metal and residual slag phases was defined as the major performance metric. The results show that the recovery ratio of metals increases as the ratio of CaO ：SiO2 by mass in the residual slag increases to 1.17. The residual content of metals in the slag decreases as the Al2O3 content of the slag is increased from approximately 8wt% to 10wt%. The recovery ratio of Cr increases with increasing L Cr ′^ m/s , and a linear relationship between L Cr ′^m/s and the activity coefficient ratio of CrO in the slag and the recovered metal phase is observed. The combination of C and SiFe or Al as the reducing agents reveals that Si is the more effective coreductant.

Basic properties of sintering dust from iron and steel plant and potassium recovery

With the production of crude steel, China produces several million tons of sintering dusts which contain a great deal of valuable metals such as, K, Na, Zn, Pb. If discharged directly without adequate treatment, these elements can lead to adverse effects on the environment. Therefore, it is very necessary to determine how to separate these elements from the dust before discharge, Several physical and chemical detection methods were used to study the basic properties of sintering dust. At the same time, preliminary experiments on the recovery of the potassium resources from the sintering dust were carried out. The mean particle size of the electrostatic precipitator （ESP） dust determined by a laser granulometer was 41.468 ~tm. Multi-point BET and single-point BET analysis showed that the surface area of the ESP dust was 2.697 mZ/g. XRD measurements detected the following phases in the ESP dust： Fe203, Fe304, KC1 and NaC1, and Fe203, Fe304 and SiO2 in the water-washed dust. SEM-EDS results proved that in the ESP dust, K mostly existed in the form of KC1 particles without being coated. Leaching experiments showed that the KCI in the ESP dust could be separated and recovered by water leaching and fractional crystallization. Through the recovery experiments, the yield of K-Na vaporized crystalline salt was 18.56%, in which the mass fractions of KCl, NaCl, CaSO4 and K2SO4 were about 61.03%, 13.58%, 14.03% and 9.97%, respectively. This process is technically viable and considerable in economic benefit. There was almost no secondary pollution produced in the whole recovery process.

Novel concept of recycling sludge and dust to BOF converter through dispersed in-situ phase induced by composite ball explosive reaction

Recycling of iron and steelmaking dusts is a key issue in environmental protection efforts and to ensure efficient utilization. In this investigation, we developed a novel recovery process that uses a dispersed in-situ phase induced by an explosive reaction of composite balls of iron and steelmaking dusts. We designed and prepared composite balls for this function using a laboratory model batch-type balling disc(at 12 r/min) and optimized the feeding modes in 180-t and 260-t basic oxygen furnace(BOF) converters. The results indicate that feeding composite balls into BOF converters is an effective novel technology for recovering iron and steelmaking dusts. The period after hot metal charging and prior to the oxygen-blowing process is the most reasonable time to feed composite balls. Composite ball treatment is not appropriate for steel production with sulfur requirements lower than 80 ppm. The maximum composite ball feeding amount is 40 kg/t and the iron yield rate is better than 95%. Compared with the conventional recycling process of sludge and dust, this novel technology is more convenient and efficient, saving up to 309 RMB per ton of steel. Further investigation of this novel recycling technology is merited.

Secondary Recovery of Columbite from Tailing Dump in Nigerian Jos Mines Field

Millions of tons of tailing dump at Rayfield mine in Jos in North Central Plateau state of Nigeria have been found to contain large quantity of columbite. Initial attempts to recover columbite concentrates by local miners and mineral speculators from the columbite rich tailing dump failed due to the ineffective processing route employed. Using cone and quartering sampling method, 0.5 kg of the columbite tailing was obtained for sieve and chemical analyses. 50 kg of <1mm fraction of the sample was subjected to a first stage magnetic concentration in a three poles Dry High Intensity Magnetic Separator (DHMS) that separated the columbite in the third pole. The re-grind of the + 0.355 mm rougher concentrate fraction (containing interlocking columbite) to pass the sieve aperture was treated on the DHMS in the second stage. The rougher concentrate undersize and columbite pre-concentrate of the first stage magnetic separation were then gravity concentrated on the air float machine. The Rayfield tailings and final concentrate were assayed using ED-XRFS to obtain 12.5% and 69.6% Nb2O5, respectively. The recovery and separation efficiency were 77.95% and 77.88% in that order. The magnetic and gravity concentrations were found effective at 77.95% recovery for columbite from the Rayfield tailing dump. This study also provided database for optimum recovery of columbite from tailings of mining sites of similar composition.

Recovery rates of iron, nickel, and chromium via iron-bath reduction of stainless steel dust briquettes based on corundum crucible erosion balance analysis

The leaching of chromium from stainless steel dust （SSD） is deleterious to the environment. To address this issue, the reduction of SSD briquettes can be employed to effectively extract chromium. The recovery rates of iron, chromium, and nickel via ironbath reduction of SSD briquettes were determined using X-ray fluorescence spectroscopy, X-ray diffraction, and scanning electron microscopy measurements. First, the effects of basicity and contents of silicon, iron, CaF2, and carbon on the recovery rates of the three metals were analyzed using the slag amount prediction model, which was originally established from the A1203 balance of corundum crucible erosion behavior. Second, the effect of feeding mode, i.e., whether steel scrap and SSD briquettes were simultaneously added, on the recovery rates was discussed in detail. Third, the iron-bath reduction of SSD briquettes was thermodynamically analyzed. The results indicated that the recovery rates of the three metals are greater than 95% those of using a basicity of 1.5 and 6.0% CaF2, 15% carbon, and 7% ferrosilicon. The recovery rate of chromium increases twofold with the addition of ferrosilicon. The feeding mode of adding briquettes and steel scrap simultaneously is better for recovery of metals and separation of the metal and slag than the feeding mode of adding steel scrap firstly and then briquettes.

铜冶炼烟尘金属分离及资源回收研究进展

以铜冶炼烟尘为研究对象,分析其理化及矿物学性质,对比铜冶炼烟尘金属分离与回收方法,包括碳热还原法、硫酸浸出法、碱性浸出法和湿法-火法联合工艺,总结各方法的原理、典型工艺、现状和存在问题,阐述非常规冶金方法在铜冶炼烟尘金属分离中的应用,展望铜冶炼烟尘资源回收的发展方向。研究结果表明:铜冶炼烟尘中砷、铜、锌含量受冶炼工艺、原矿品质的影响,不同元素赋存形态存在差异。碳热还原法可以通过金属砷酸盐和氧化物分解的方式释放砷,从而实现砷与其他有价金属的分离;硫酸浸出法可以高效浸提铜冶炼烟尘中的金属,实现多元素的回收;碱性浸出法可选择性浸提砷;湿法-火法联合工艺结合了火法工艺选择性分离砷和湿法工艺高效提取金属的优点,对于复杂高砷铜冶炼烟尘处理具有优势。铜冶炼烟尘兼具资源属性和环境风险,实现清洁生产及多金属资源化利用仍是关键,砷的无害化处置与锌、铜、铅等有价金属的高效协同回收工艺及分离机制、全过程物质流与环境效应是铜冶炼烟尘资源回收的发展方向。

含砷冶炼烟尘选择性脱砷与铜锌回收研究

含砷冶炼烟尘是有色金属冶炼中产生的一类重要二次资源,但砷具有剧毒性,限制其清洁化利用。根据含砷烟尘中砷物相特征,采用水浸-氧化酸浸梯次脱砷,利用溶剂萃取回收铜锌,实现烟尘资源的综合利用。对于易溶相As_(2)O_(3),在液固比4∶1、温度95℃和时间3 h的条件下进行水浸,砷浸出率为52.85%,水浸液在120℃温度下蒸发结晶回收砷。对于难溶相Pb5(AsO4)3Cl,在温度45℃、液固比3∶1、硫酸浓度1.5 mol/L、H_(2)O_(2)浓度3.0%和反应时间4 h的条件下进行氧化酸浸,砷、铜和锌的浸出率分别为99.16%、99.67%和98.64%,酸浸渣可作为炼铅原料。浸出液中,铜和锌分别采用萃取剂N902和P204进行回收,其萃取率分别为96.42%和96.38%。含砷冶炼烟尘选择性脱砷和铜锌萃取组合工艺具有脱砷效率高、成本低、安全环保等优点,适用于含砷物料资源化清洁利用。

转炉干法除尘煤气回收能效评价方法研究

转炉干法除尘煤气回收效率会受多种因素的影响,其中,回收期间的空气吸入量和氧枪吹氧量的控制的影响尤为显著。因此,本文通过转炉煤气回收机理模型、工业互联网平台等技术手段,对两者进行监测和评价,从而提升整体煤气回收效率。

炭渣碱化焙烧模拟浸出液制备冰晶石

以铝电解槽炭渣纯碱焙烧后的浸出液制备冰晶石是炭渣高效利用的关键.但在冰晶石合成过程中,钠、铝等组元的竞争反应会降低浸出液中氟的回收率.为了进一步研究冰晶石和主要杂质的反应机理,利用氟化钠和铝酸钠配制模拟浸出液,以制备冰晶石的形式回收氟,并分析了浸出液的铝氟比(Al与F的摩尔比,下同)、反应终点pH值和温度对氟回收率的影响.结果表明:在氟铝配合离子的优势区间内,更易于冰晶石的合成;当浸出液中铝氟比为1∶6、反应终点pH值为8、温度为20℃时,制备的冰晶石形貌良好,氟的回收率达到98.89%.

锡冶炼烟尘中锡、锌、镉的分离回收工艺研究

研究了采用硫酸浸出—氧化水解脱砷—锌粉置换镉工艺分离回收锡冶炼烟尘中的锡、锌、镉,考察了各因素对分离回收效果的影响。结果表明:在初始硫酸浓度15%、液固体积质量比3∶1、浸出时间120min、浸出温度90℃条件下,Zn、Cd浸出率分别为93.25%、89.35%,Sn浸出率小于0.1%;浸出液在双氧水加入量为2%、控制终点pH为5时,除砷后夜中As质量浓度降至0.1mg/L;除砷后液在反应温度60℃、锌粉用量为理论量1.0倍、搅拌速度250r/min、反应时间30min条件下,可得到含镉95%以上的海绵镉。该工艺可实现锡冶炼烟尘中有价金属高效回收利用。

锂辉石焙烧过程中窑尾高温烟气净化处理装置的工程应用

锂辉石焙烧转型过程中产生的窑尾烟气特性有:高温、夹带有价粉尘、含NOx及SOx等污染性气体。以某企业年产6万吨碳酸锂项目为例,研究锂辉石在焙烧转型过程中高温尾气中有价粉尘回收、热量回收及烟气净化处理的工程应用。采用金属膜除尘器回收有价粉尘,SCR技术脱硝,烘干机回收烟气热量,石灰石石膏法脱硫的综合处理工艺,取得很好的处理效果:金属膜收尘器回收有价粉尘约9,000 t/年,带来直接经济效益约2,700万元;高温烟气的热量回收,为企业节约2,196,000 Nm^(3)/年的燃气量,节约燃气费用约878.4万元/年,NOx的排放指标低于80 mg/Nm^(3),SOx的排放指标低于50 mg/Nm^(3),满足环保排放要求。该工艺不仅实现对烟气中NOx、SOx等污染气体进行净化,同时也实现烟气的有价粉尘的回收及热量回收,为企业实现最大经济效益,同时也为同行业提供相关参考依据。

粗铅冶炼过程中砷镉铊的走向分布及治理措施

在粗铅冶炼工艺中,铅精矿和其他含铅物料中的砷、镉、铊分布于各工序环节,不利于有价金属资源的回收,而且加大了冶炼废弃物的处理难度,另外还对人体健康和环境造成负面影响。现有文献对于砷、镉、铊在粗铅冶炼过程中的分布及趋向还未见报道,本文根据某冶炼企业实际生产情况,统计了2021年及2022年分别为期14d的两套物料平衡数据,对砷、镉、铊在各冶炼工序的分布进行了分析,得到以下结论。砷的分布情况:在底吹炉工序中,约85%砷进入高铅渣,约9%砷进入烟灰,约6%砷进入硫酸净化污酸系统;在还原炉工序,约70%以上砷形成铅铜锍进入粗铅,约20%砷进入还原炉烟灰,10%以下的砷通过还原渣进入烟化炉。镉、铊的分布情况:高度富集于底吹炉和侧吹炉烟灰中,其中底吹炉烟灰中富集比例为85%~95%,只有5%~15%进入高铅渣转至还原炉工序,极少部分进入硫酸系统。企业采用开路底吹炉烟尘方式减少粗铅冶炼系统中砷、镉、铊的含量,开路标准是烟尘含镉超过20%时从收尘系统开路,当烟尘含镉低于15%停止开路,取出的烟尘可直接作为回收镉的原料外售。本文分析结果及解决方法可为同类企业控制冶炼系统中砷镉铊的分布提供参考。

尿素造粒塔粉尘回收系统设计思路与运维方法

为了实现尿素造粒塔塔顶尾气的达标排放,阐述了尿素造粒塔粉尘回收系统的设计思路、造粒塔通风量的确定过程及改造后达到的效果。系统建成投产后,出现了造粒塔“粘塔”问题,分析了具体的原因并制定了应对措施。

电解废液与锌冶炼烟尘协同处理试验研究

为综合回收锌冶炼烟尘及电解废液中的有价金属,本研究进行了利用锌电解废液浸出锌冶炼烟尘试验,通过一段浸出、碳酸钠中和沉锌及氢氧化钠中和沉镁等工序获得了沉锌产品和沉镁产品,通过两段浸出、萃取反萃、中和沉铟等工序获得了富铟渣及副产物铅银渣。试验最佳工艺条件:一段浸出为液固比4:1,浸出温度80℃,浸出时间75 min,在此条件下,锌浸出率可达78.69%,铟浸出率仅为8.4%;锌镁分离最佳终点pH值区间为6.86~7.80;二段浸出最佳工艺条件为终点pH值1.08,液固比3:1,浸出温度75℃,浸出时间10 h,在此条件下,铟浸出率可达86.84%。该研究可为炼锌厂开路除杂及综合回收有价金属提供新思路。

硫化砷渣协同处理铜冶炼烟尘浸出液回收铜

为充分回收铜冶炼过程产生的硫化砷渣和烟尘中的铜资源,降低对环境的影响,贯彻“以废治废”的理念,采用硫化分离技术,用铜冶炼生产过程产生的硫化砷渣沉淀富铜液回收铜冶炼固废中的铜资源。系统探究了沉淀过程中温度、硫化渣用量、反应时间对沉铜效率和硫化砷利用率的影响。结果表明:在反应温度80℃、每100 mL富铜液使用4.5 g硫化砷渣、反应时间3.5 h时具有最良好的铜沉淀效果,该条件下对应的铜沉淀率为88.92%,沉铜后的溶液中铜含量为0.36 mg/L,沉淀铜后所得铜渣中铜的质量分数为55.14%,砷的质量分数为3.18%,符合返回熔炼炉冶炼回收铜的要求;沉淀铜渣中的As主要来源于原料硫化砷渣,原料硫化砷渣中经氧化产生的少量As 2O 3在沉淀过程中不与稀硫酸反应,随着铜的沉淀一起沉到铜渣中。使用硫化砷渣沉淀铜可减少传统硫氢化钠沉淀铜过程中硫化氢气体的产生,全生产链为“以废治废”,且生产环境友好,结果可为铜冶炼企业提供参考。

某低品位斑岩铜矿短流程工艺优化试验及工业应用研究

江西某铜矿原矿品位低,属典型的大型斑岩铜矿,近年来随着开采逐步深入,矿石愈发难磨,有用矿物单体解离度逐渐降低,严重影响了生产指标。据流程考查结果可知,尾矿中损失的铜大部分赋存在粗粒级中,其中+0.097mm粒级的铜金属分布率高达59.71%。为了充分回收尾矿中损失的铜,进一步提高选铜回收率,结合大型浮选机,开展短流程优化工艺试验及工业应用研究。通过缩短主干流程,强化矿浆调节,有针对性地加强粗颗粒回收,开展了详细的实验室试验及工业试验研究,实验室试验采用短流程优化工艺后获得的铜回收率相比生产工艺提高了1.04个百分点,工业试验累计指标相比优化前正常生产提高了1.02个百分点。

鞍钢10号3200 m^(3)高炉炉顶均压煤气回收技术应用

针对高炉煤气直接排入大气对环境造成污染的问题,开展了高炉炉顶均压煤气回收技术应用实践。实践后,煤气回收率达到81%,减少高炉炉顶粉尘排放175 t/a,减少碳排放量约为1151 t/a,创效112万元/a,取得了良好的经济效益和环保效益。