Utilization of nickel slag using selective reduction followed by magnetic separation

In order to utilize slag discarded by nickel plants, the selective recovery of nickel and copper versus iron was investigated by selective reduction, which was achieved by controlling the reduction parameters and magnetic separation process on bench scale. The results show that increasing the basicity （mass ratio of CaO to SIO2） of nickel slag facilitates the enrichment of nickel and copper The process parameters for selective reduction were optimized as follows： basicity of 0.15, reducing at 1200 ~C for 20 min, 5% coal on a dried slag mass base. The grinding-magnetic separation results of reduced briquettes show that concentrate containing 3.25%Ni, 1.20%Cu and 75.26%Fe is obtained and selective enrichment is achieved with a recovery of 82.20%, 80.00% for nickel and copper respectively, while the recovery of iron is only 42.17%. The S and P contents are not reduced obviously and further research may be needed to examine the behaviors of S and P in the process.

Extraction of arsenic from arsenic-containing cobalt and nickel slag and preparation of arsenic-bearing compounds

The arsenic extraction from the arsenic-containing cobalt and nickel slag,which came from the purification process of zinc sulfate solution in a zinc smelting factory,was investigated.The alkaline leaching method was proposed according to the mode of occurrence of arsenic in the slag and its amphoteric characteristic.The leaching experiments were conducted in the alkaline aqueous medium,with bubbling of oxygen into the solution,and the optimal conditions for leaching arsenic were determined.The results showed that the extraction rate of arsenic was maximized at 99.10%under the optimal conditions of temperature 140 ℃,NaOH concentration 150 g/L,oxygen partial pressure 0.5 MPa,and a liquid-to-solid ratio 5：1.Based on the solubilities of As2O5,ZnO and PbO in NaOH solution at 25 ℃,a method for the separation of As in the form of sodium arsenate salt from the arsenic-rich leachate via cooling crystallization was established,and the reaction medium could be fully recycled.The crystallization rate was confirmed to reach 88.9%（calculated on the basis of Na3AsO4） upon a direct cooling of the hot leachate down to room temperature.On the basis of redox potentials,the sodium arsenate solution could be further reduced by sulfur dioxide（SO2） gas to arsenite,at a reduction yield of 92%under the suitable conditions.Arsenic trioxide with regular octahedron shape could be prepared successfully from the reduced solution,and further recycled to the purification process to purify the zinc sulfate solution.Also,sodium arsenite solution obtained after the reduction of arsenate could be directly used to purify the zinc sulfate solution.Therefore,the technical scheme of alkaline leaching with pressured oxygen,cooling crystallization,arsenate reduction by SO2 gas,and arsenic trioxide preparation,provides an attractive approach to realize the resource utilization of arsenic-containing cobalt and nickel slag.

Enhancement of the nickel converter slag-cleaning operation with the addition of spent potlining

The slag cleaning(or matte settling) process was experimentally investigated at 1573 K using a fayalitic nickel converter slag containing spinel and matte/alloy particles.The addition of various amounts of spent potlining(SPL) was studied in terms of its influence on matte settling and the overall metal recoveries.The slags produced were characterized by scanning electron microscopy,energy-dispersive spectroscopy,and wet chemical analysis using inductively coupled plasma optical emission spectrometry.The presence of solid spinel particles in the molten slag hindered coalescence and settling of matte/alloy droplets.Matte settling was effectively promoted with the addition of as little as 2 wt% SPL because of the reduction of spinel by the carbonaceous component of the SPL.The reduced viscosity of the molten slag in the presence of SPL also contributed to the accelerated matte settling.Greater metal recoveries were achieved with larger amounts of added SPL.Fast reduction of the molten slag at 1573 K promoted the formation of highly dispersed metal particles/clusters via accelerated nucleation in the molten slag,which increased the overall slag viscosity.This increase in viscosity,when combined with rapid gas evolution from accelerated reduction reactions,led to slag foaming.

Improvement of carbothermic reduction of nickel slag by addition of CaCO3

The effect of CaCO3 addition on the carbothermic reduction of nickel slag was studied,and the mechanism of CaCO3 in improving the reduction was analyzed.The results showed that when the CaCO3 content added to the slag was increased from 0 to 8 wt.%,initiation temperature of the carbothermic reaction decreased from 1100 to 1000℃,the temperature reaching the maximum reduction rate decreased from 1150 to 1100℃,and the reduction degree of the nickel slag increased from 58%to 88%.The iron particles in the reduced nickel slag were coarsened and the X-ray diffraction intensity of metallic iron peaks increased,confirming that the addition of CaCO3 was beneficial to the reduction of nickel slag and recovery of iron.

Effect of additives on growth of ferronickel grains and metal-slag separation behavior

Na_(2)S,Na_(2)CO_(3),FeO,FeS and carbon were used to regulate the properties of slag or metal fractions,and their effects on metal growth and metal–slag separation behavior were investigated.The growth of ferronickel grains can be enhanced by adding these additives,and Na_(2)S was the most effective.Na_(2)S,Na_(2)CO_(3) and FeO mainly affected the properties of slag,while carbon and FeS affected the metal fraction.The onset temperature of metal–slag separation was 1297℃ for the sample without additive,which was decreased to 1123 and 1101℃ after adding 3.30 wt.%Na_(2)S and 4.47 wt.%Na_(2)CO_(3),respectively.The onset temperature of metal–slag separation was mainly controlled by the slag fraction.The average apparent activation energy of metal grain growth was 125.32 kJ/mol without additive,and it decreased obviously after adding different additives.Na_(2)S also had the most remarkable effect on the decrease in activation energy.

Application of Modified Nickel Slag Adsorbent on the Removal of Pb^(2＋) and Cu^(2＋) from Aqueous Solution

Al（OH）_3 modified nickel slag adsorbent was prepared by sintering technology. The structure of the sample was characterized by BET, XRD, IR, SEM and EDAX. The sample＇s adsorption performance of Pb^（2＋） and Cu^（2＋） from aqueous solution was studied. Results indicated that the adsorbent is a loose and porous mesoporous material. Its surface had mass aluminosilicate, high-activity γ-Al_2O_3 and its p H ranges from 4 to 12 that all have negative charges. The BET surface of the adsorbent is 23.90 m^2/g. Furthermore, its surface contains rich oxygenic functional groups, which could not only provide abundant adsorption sites for Pb^（2＋） and Cu^（2＋）, but also improve the adsorption performance of Pb^（2＋） and Cu^（2＋） from waste water through the complexation of heavy metal ions. The best p H values selected in the adsorption of Pb^（2＋） and Cu^（2＋） are 6 and 5, respectively. With the increase of the initial concentration of simulated solution, the adsorption capacities of Pb^（2＋） and Cu^（2＋） gradually increased but the removal rates showed a downward trend. The competitive adsorption results of Pb^（2＋） and Cu^（2＋） showed that Pb^（2＋） has better preferential adsorption than Cu^（2＋）.

Adsorption of Pb^2+and Cu^2+with Unburned Desulphurization Slag Modified Nickel Slag

Desulphurization slag modified nickel slag adsorbent was prepared by unburned forming technology. The structure of the sample was characterized by BET,XRD,IR,SEM and EDAX. The adsorption performance of Pb^2＋ and Cu^2＋ onto the resultant adsorbent from aqueous solution was studied. Results indicated that the adsorbent possesses a network pore structure formed by the AFt and C–S–H through cross lapping; the adsorbent contains a large number of Si–OH and Al–OH functional groups. The presence of functional groups not only provides abundant adsorption sites for Pb^2＋ and Cu^2＋,but also improves the adsorption performance of Pb^2＋ and Cu^2＋ from waste water through the complexation of heavy metal ions. The result of specific surface area analysis showed that the adsorbent sample possesses mesoporous structure and the BET specific surface area is 27.15 m^2/g. The solution p H values for the adsorption of Pb^2＋ and Cu^2＋ were optimized to be 6 and 5.5,respectively. The adsorption capacities of Pb^2＋ and Cu^2＋ gradually increase,whereas the removal rates of the two metal ions decrease with increasing the initial concentration of simulated solution. The resultant adsorbent gives a higher adsorption capacity for Cu^2＋ than for Pb^2＋ in the single ion solution. However,it shows preferential adsorption of Pb^2＋ rather than that of Cu^2＋. Meanwhile,results of recyclability indicate the remarkable regeneration capacity,re-adsorption ability and reusability performance of the adsorbent sample.

Leaching of magnesium from desiliconization slag of nickel laterite ores by carbonation process

The leaching of magnesium from desiliconization slag of nickel laterite ores by carbonation process was studied.The influence of various parameters was investigated to optimize the conditions and determine the kinetics of the reaction.The results show that with increasing stirring speed,liquid-to-solid ratio and reaction time,and decreasing temperature,the leaching rate of magnesium enhances.The leaching process of the desiliconization slag in the range of 288-298 K is controlled by the surface chemical reaction model.The apparent activation energy is-20.45 kJ/mol,and the kinetics model is obtained.

Slag Resistance of Refractories for Direct Reduction of Laterite Nickel Ores in Rotary Kilns

Aiming at prolonging the service life of refractories for direct reduction of laterite nickel ores in rotary kilns,the slag resistance of ten materials(corundum bricks,chrome corundum bricks,silicon nitride bonded silicon carbide bricks,high alumina silicon carbide bricks,high alumina bricks,magnesia chrome bricks,magnesium aluminate spinel bricks,spinel chrome corundum bricks,chrome corundum castables and magnesia alumina chrome composite spinel bricks)was evaluated by rotary slag tests,which simulate the service conditions in rotary kilns.The corroded residual bricks were analyzed by SEM and EDS.The results show that the magnesia alumina chrome composite spinel brick possesses the advantages of magnesium aluminate spinel bricks and chrome corundum bricks;MgO-rich spinel can absorb the penetrated ferric oxide,and forms a dense zeylanite layer,which prevents the penetration of the molten laterite nickel ores;therefore,it is an ideal lining of rotary kilns for direct reduction of laterite nickel ores.

响应曲面法优化二次镍渣微晶玻璃热处理制度

镍渣作为有色冶炼过程产生的冶金废渣,以堆存形式处理,环境影响突出,但含铁量高,是一种极具开发前景的二次利用资源。以二次镍渣为原料制备微晶玻璃,采用响应曲面法并结合Box-Behnke原理设计探讨了核化温度、核化时间、晶化温度、晶化时间及其交互作用对微晶玻璃抗折性能的影响,建立了抗折强度与各因子间的模型。通过模拟优化,确定了最佳热处理工艺参数:核化温度和晶化温度分别为845℃和955℃、核化时间和晶化时间均为80 min。采用最优工艺参数试验验证发现,微晶玻璃主晶相为铁硅灰石和钙长石,抗折强度均值达到126.78 MPa,与模型预测值偏差较小,表明该预测模型可靠有效及工艺优化合理可行。

单组分电炉镍渣基地聚物修补材料制备与性能调控

为利用具有潜在活性的固体废弃物电炉镍渣,制备单组分电炉镍渣基地聚物修补砂浆.基于正交实验和极差分析,通过掺入掺合料并改变碱模数和碱当量等关键影响因素,对地聚物砂浆各项修补性能进行调控,获取满足修补性能的最优配合比,确定各因素对修补性能的影响主次.结果表明,最优配比是矿渣掺量为30%,粉煤灰掺量为30%,碱模数为1.2,碱当量为6.5%,其28 d抗压、抗折强度分别为90.29、9.23 MPa,干燥收缩率为0.56×10-3,14 d拉伸粘结强度为3.64 MPa,满足修补砂浆规范要求.经比较,矿渣掺量对修补砂浆性能调控影响最为显著.

Recovery of valuable metals from spent lithium ion batteries by smelting reduction process based on FeO-SiO_2-Al_2O_3 slag system

NA novel smelting reduction process based on FeO-SiO2-Al2O3 slag system for spent lithium ion batteries with Al cans was developed, while using copper slag as the only slag former. The feasibility of the process and the mechanism of copper loss in slag were investigated. 98.83% Co, 98.39% Ni and 93.57% Cu were recovered under the optimum conditions of slag former/battery mass ratio of 4.0：1, smelting temperature of 1723 K, and smelting mass ratio of time of 30 min. The FeO-SiO2-Al2O3 slag system for the smelting process is appropriate under the conditions of m（FeO）：m（SiO2）=0.58：1？1.03：1, and 17.19%？21.52% Al2O3 content. The obtained alloy was mainly composed of Fe-Co-Cu-Ni solid solution including small amounts of matte. The obtained slag mainly consisted of fayalite and hercynite. Meanwhile, the mechanism of copper loss is the mechanical entrainment from strip-like fayalite particles in the main form of copper sulfide and metallic copper.

基于调渣提铁的镍冶炼渣熔化温度调控

目前,镍渣提铁工艺存在提铁效率低、工艺实施难度大、成本高等问题。本文通过相图分析、单因素和正交实验等方法,研究了炉渣中主要氧化物含量对半球点温度的影响,得到了有利于提铁的炉渣渣型优化方案。结果表明:当CaO含量(质量分数)为25%、MgO含量为9%、铁硅比为0.8时,该渣型的半球点温度最低。考虑到现行工艺,选择MgO含量为13%、CaO含量为20%、铁硅比为1.0为较优方案,所得炉渣的半球点温度明显低于现行顶吹炉渣的半球点温度。调整后的炉渣中含铁物相由以硅酸亚铁为主转化为以钙铁榴石和铁氧化物为主,有利于后续提铁。

镍冶炼渣中铁资源回收研究现状及发展分析

镍渣为有色冶炼过程中产生的冶金废渣,铁品位高达40%,具有较高的回收利用价值。镍渣中的铁主要以硅酸亚铁形式的化合物为主,难以对其进行有效提取。如何合理利用镍渣,对行业可持续、绿色化发展具有重大意义,是目前的研究热点。本文对镍渣中铁资源回收技术进行了综合分析,针对现有镍渣提铁工艺中存在的问题,提出在镍冶炼过程中加钙以调整镍渣渣型和降低冶炼温度,使铁橄榄石向铁酸钙形式转变,降低后续提铁难度,以期实现镍渣的高值资源化综合利用。

镍渣—全尾砂混合骨料配比试验研究

为实现固废循环利用,降低尾砂和镍渣的固废堆存,开展了镍渣—全尾砂混合骨料配比试验。通过扫描电镜和X射线荧光光谱测定(XRF)方法分析了镍渣和全尾砂的粒级分布和化学成分,利用骨料堆积密实度理论确定了镍渣—尾砂的配比优化范围为4∶6、5∶5和6∶4;考虑料浆的流动性、和易性及充填体强度,最终推荐镍渣—全尾砂的最优配合比为5∶5,料浆的质量浓度为77%~79%,水泥添加量为310 kg/m^(3);针对镍渣—全尾砂充填,镍渣利用量最高不超过50%,最大质量浓度为79%,对应的剪切应力为112.634 Pa,黏度为0.938 Pa·s。

遵义某钼镍矿矿渣自燃机理及防治方法探讨

为对自燃钼镍矿矿渣开展综合治理,通过遵义某钼镍金属矿矿渣现场调查及样品采集分析,查明了钼镍矿矿渣的矿物成分、元素含量及主要自燃气体成分,初步确定钼镍矿矿渣自燃的引燃物为黄铁矿,提供可持续燃烧的可燃物主要为炭质,当矿渣自身属性满足要求,供氧及聚热条件达到某一平衡时,便会发生自燃;提出了“降温+切断供氧通道”,“注浆+覆盖”综合治理措施以及尚未自燃矿渣的预防建议。工程验证治理取得了良好的效果,研究成果为同类型工程问题提供了一定的解决经验和思路。

高含碳煤渣硫酸熟化——水浸法回收钒、镍

印度某高含碳含钒煤渣含钒3.57%、镍1.19%,具有较高回收价值,但该渣碳含量较高(14.61%),采用传统直接浸出效果较差。首先采用氧化焙烧对该含钒煤渣进行脱碳预处理,然后采用硫酸熟化—水浸技术提取其中的钒和镍。重点研究了焙烧、硫酸熟化和水浸工艺参数条件对钒、镍的浸出的影响。结果表明,最优焙烧温度和时间分别为800℃、2h;焙砂的最佳浸出粒度为-0.075mm占比90%;最佳熟化工艺参数条件为:酸料比1.5∶1、熟化温度200℃、熟化时间1h;最佳水浸条件为:固液比4∶1、水浸温度95℃、水浸时间2.5h;在上述最佳工艺参数条件下,钒的浸出率可高达96%,镍的浸出率约53%。

镍基镁渣催化剂对生物质焦油模化物催化重整特性实验研究

采用湿浸渍法制备Ni/γ-Al_(2)O_(3)和Ni/MS(magnesium slag)催化剂,选择糠醛、甲苯、萘、芘作为生物质焦油的模化物,研究不同镍基催化剂对四类焦油模化物在固定床反应器内进行催化重整的重整特性。结果表明,Ni/MS催化剂在催化所有模化物的重整反应时,气相碳转化率和气体产率均明显高于Ni/γ-Al_(2)O_(3)催化剂。当水分子物质的量与碳原子物质的量之比为1.5时,糠醛的气相碳转化率达到最高值86.54%。X射线衍射(XRD)结果表明,Ni/MS催化剂上存在的多种固溶体(NiO-Fe_(2)O_(3)、NiO-MgO)形成了多种活性位点。

镍渣对粉煤灰基地质聚合物收缩性能的影响

镍渣是镍冶炼过程中排出的工业固废,以镍渣为原料制备地质聚合物,既提高了地质聚合物的绿色环保属性,更有助于促进镍铁合金工业的可持续发展。向粉煤灰基地质聚合物中掺入镍渣,并考察镍渣掺量对硬化体收缩性能的影响。结果表明,镍渣掺量为25%时不仅提高了地质聚合物的抗压强度,同时有助于降低自收缩和干燥收缩。镍渣反应活性较低,掺入粉煤灰基地质聚合物中会减缓碱激发反应进程,进而降低硬化体自收缩。另一方面,镍渣颗粒在硬化体中发挥微骨料作用,掺入后有助于降低地质聚合物孔隙率,既提高了硬化体的抗压强度,同时抑制干燥过程中的水分蒸发并降低了干燥收缩。

镍冶炼渣矿物学特征对浮选回收镍、铜的影响

为回收利用镍冶炼渣中的镍和铜等有价金属,本文以我国某镍冶炼渣为研究对象,利用多种矿物学特征分析手段,深度解析镍冶炼渣的矿物学特征对浮选回收渣中镍、铜回收的限制,并提出利用源头焙烧改性优化有价金属镍、铜的结晶状态,进而提高镍、铜浮选回收率。研究结果表明,镍冶炼渣中主要的有价金属镍、铜的品位分别为0.88%和0.31%,在可浮性较差的氧化态和残余态中的占比达20%左右,可浮性较好的镍、铜主要赋存于镍黄铁矿、斑铜矿和硫镍矿中,但是这三种矿物相多以微细粒不规则状散乱分布在硅酸盐矿物相间,难以实现单体解离;镍、铜较差的结晶状态导致其浮选回收率分别仅有24.61%和38.77%,优化镍铜在渣中的结晶状态成为提高其浮选回收率的关键所在。在焙烧改性后,镍、铜在可浮性较好的金属态和硫化态中的占比均高达90%以上,其浮选回收率也分别提高了41.55%和41.23%。