回收沉金后液中有价金属的工艺优化探讨

通过分析回收沉金后液中有价金属生产中存在的问题,提出对沉铂钯工序中的锌粉置换与水解碲两个过程进行优化。试验研究了沉铂钯工序的最佳工艺条件,并选择液碱代替片碱,优化了铜阳极泥处理工艺路线,将其应用到实际生产中,一年可以减少22.91 t碲的系统占用,为企业直接变现至少1145.3万元。

SO_2还原沉金后液回收硒碲及捕集铂钯

以沉金后液为原料,通过SO2直接还原回收硒碲和捕集铂钯。采用X射线衍射仪(XRD)和扫描电镜(SEM)对还原产物的物相、微观形貌进行表征,结果表明:当反应温度为85℃,SO2流量为0.2 L/min,反应时间为4 h,H+浓度为3.3 mol/L和Cl?浓度为0.72 mol/L时,Se和Te回收率分别为99.5%和96.64%,Pt和Pd回收率均达到了100%,所得黑色还原产物中硒、碲、铂和钯的质量分数分别为28.06%、52.3%、0.084%和0.588%。产物中硒和碲均以单质态形式存在,其形貌为球状体和柱状体。

卤素离子催化作用下SO_2还原沉金后液及其热力学特征

以沉金后液为原料,采用SO_2为还原剂,研究在卤素以及卤素复合催化剂存在条件下还原沉金后液中的硒碲以及捕集贵金属金铂钯的工艺。结果表明:在85℃、硫酸浓度167 g/L、SO_2流量0.2 L/min的条件下,当Cl-催化剂浓度为1.1 mol/L、反应时间2 h,或当Br^-催化剂浓度为0.5 mol/L、反应时间3 h,或当I^-催化剂浓度为0.3 mol/L、反应时间2 h时,硒金铂钯还原率达到100%,碲还原率达到99.60%以上。采用卤素复合催化剂,当Na Cl与Na Br摩尔比为1:2时,有助于加快硒碲的还原,而且降低了催化剂的用量。SO_2催化还原后产物中含碲74.56%、铜11.85%、硒7.38%,贵金属金3.89%、铂0.19%、钯1.02%(质量分数);还原产物中碲以单质状态存在,产物形貌为球状体。热力学分析表明:硫酸浓度为167 g/L时,Se(Ⅳ)主要以H_2Se O_3形式存在,Te(Ⅳ)主要以H_3Te O_3^+形式存在;当溶液中有Cl^-存在时,溶液中H_3Te O_3^+在Cl^-缔合作用下逐渐转变为Te Cl_6^(2-),其电极电势较H_3Te O_3^+的正,促进碲的还原。

F树脂吸附沉金后液中贵金属的试验研究

大冶有色金属有限责任公司冶炼厂的铜阳极泥经处理后生成的沉金后液中含有少部分的Au与大部分Pt与Pd,为提高贵金属的回收率,公司选择在沉金后液中直接回收贵金属,进行了大量试验。试验采用二级交换柱设备探索了F树脂对沉金后液中Au、Pt、Pd贵金属离子的吸附情况,试验结果表明:F树脂对Pt离子的吸附效果一般,对Au离子与Pd离子的吸附效果较好;在0~300h之间,一级树脂交换柱对Au离子与Pd离子的吸附效果较好;在120~300h之间,二级交换柱吸附Pt离子的效果较好;在120-430 h之间,二级交换柱树脂吸附后液中Au与Pd的离子浓度很低;温度和流速对F树脂对Pd离子的吸附效果影响不大;降低流速和提高原液的吸附温度,可以提高F树脂对Pt离子的吸附效果。

从沉金后液中回收碲的试验探索

大冶稀贵车间从沉金后液中回收碲,工艺流程长,生产成本高,碲直收率仅有38.68%,公司欲改进此工艺。由于沉金后液中的碲有一部分是正六价形态存在,而正六价碲易溶于热水,不溶于碱液,正四价碲溶于碱液,基于此,本文设计了还原沉碲-碱浸还原渣-碱浸液除杂-中和沉碲工艺路线,并进行了调pH值Na2SO3还原沉碲和直接Na2SO3还原沉碲两类试验,实验结果表明:沉金后液调pH至1.9时,沉碲效果最好,碲浸出率76.9%,产品中TeO2含量64.6%,碲直收率达到54.95%;pH调整过高,会有正六价碲析出,降低碲回收率;pH调整过低,会有单质碲析出,导致碲的碱浸率降低;贵金属Pt、Pd分散损失很少,在碱浸渣中得到很好的富集;低的碱浓度有利于碲的浸出;提高NaOH浓度,碱浸液中的杂质含量显著升高;Na2S、CaCl2能较好的除去碱浸液中重金属杂质。该试验工艺不仅缩短了碲的回收工艺流程,降低生产成本,而且可以提高碲的直收率。

树脂吸附法从沉金后液中回收金铂钯的实践

采用树脂吸附法,利用QPTU树脂,控制温度30~40℃,回收沉金后液中的Au、Pt、Pd贵金属,可以控制尾液含金、铂、钯在0.2mg/L以下。结果显示,该树脂对沉金后液中的Au、Pt、Pd都有很好的吸附效果;在此运行温度条件下并没有发生降解;该树脂的吸附突破顺序依次是Pt、Pd和Au。

降低亚钠法沉金后液含金量的工业试验

针对某冶炼厂沉金工序生产时存在沉金后液含金量偏高,导致铂钯精矿含金量升高和金生产成本过高的现状,对影响沉金后液含金量的pH值、氯酸钠添加量、氯气量、温度、药剂种类和反应终点的判断方式等因素进行试验分析。根据试验分析结果,并结合实际生产情况,通过采取降低氯酸钠的添加量、提高沉金过程的温度、增加电位检测等优化措施,沉金后液含金量由85.3 mg/L降至4.6 mg/L,进而降低了黄金生产的成本。

沉金后液中金、铂、钯、碲的组态特征及其碲捕集稀贵金属机制

铜阳极泥沉金后液是回收铂族金属铂、钯的重要原料来源。根据铜阳极泥氯化浸出过程稀贵金属可能发生的电极反应,分析了沉金后液中金、铂、钯、碲的存在价态,通过热力学计算绘制了金、铂、钯、碲的多形态组分图,并研究了单一金、铂、钯体系碲捕贵金属机制。沉金后液中稀贵金属金、铂、钯和碲的价态分别为Au^(3+),Pt^(2+),Pt^(4+),Pd^(2+),Te^(4+);金、铂、钯在沉金后液中随氯离子浓度的改变,以多组态络合物形式存在,Au(Ⅲ)几乎全部以[AuCl_(4)]-组态存在,Pt(Ⅱ),Pd(Ⅱ)分别主要以[PtCl_(4)]_(2)-,[PdCl_(4)]_(2)-绝对优势组态存在,Pt(Ⅳ)以[PtCl_(6)]_(2)-为主、[PtCl_(4)]和[PtCl_(5)]-并存的多组态存在,Te(Ⅳ)随pH的变化形成不同酸根离子组态,在强酸性条件下主要形成H_(3)TeO_(3)^(+)。钯单一体系还原碲捕集贵金属主要形成PdTe_(2),铂单一体系还原碲捕集贵金属主要形成PtTe_(2)和Pt_(2)Te_(3),金单一体系还原碲捕集贵金属产物主要为单质Au和Te,并有少量AuTe_(1.7)物相。沉金后液中碲捕集铂、钯主要形成碲化物,碲捕集金主要形成单质金及少量碲化物。

焦亚硫酸钠复合还原硒、碲、金、铂、钯的热力学及动力学特征分析

采用焦亚硫酸钠复合还原沉金后液回收硒、碲和捕集金、铂、钯。通过正交实验考察各因素对硒、碲、金、铂、钯还原率的影响,并对焦亚硫酸钠、SO_2和水合肼复合还原沉金后液进行动力学及热力学特征分析。结果表明:采用焦亚硫酸钠、SO_2和水合肼复合还原沉金后液,对硒、碲还原率的影响从大到小的顺序为反应时间、焦亚硫酸钠用量、水合肼用量。通入SO_2至饱和后,当水合肼用量为1.5 mL/L,焦亚硫酸钠为30 g/L,SO_2流量为0.4 L/min,每反应1h通入0.5 h SO_2,反应时间为9 h时,金、铂、钯的还原率均达到100%,硒和碲的还原率分别为71.50%和90.30%。焦亚硫酸钠复合还原硒、碲符合一级反应动力学规律,还原硒、碲的表观活化能分别为52.533 kJ/mol和70.828 kJ/mol,硒、碲的还原属化学反应控制。热力学分析表明,沉金后液中金、铂、钯、硒、碲分别以AuCl_4^-、PtCl_4^(2-)、PdCl_4^(2-)、H_2SeO_3、TeCl_6^(2-)形态存在,焦亚硫酸钠、SO_2主要以H_2SO_3形态存在,水合肼以N_2H_5^+形态存在。

双氧水氧化碱浸分离铂钯精矿中硒碲热力学及实验研究

采用水合肼和盐酸羟胺复合还原沉金后液得到铂钯精矿,其中硒和碲总含量达到71.15%,金、铂和钯总含量达到3.65%,从铂钯精矿中分离硒碲对富集及回收贵金属金铂钯具有重要意义。热力学分析表明:在碱性条件下,采用双氧水作为氧化剂,可以将硒和碲氧化为高价态的离子化合物被浸出,金、铂和钯留在固相中。采用双氧水氧化碱浸分离铂钯精矿中硒碲,实验结果表明其适宜反应条件为:双氧水用量为250 m L/L,Na OH浓度为5 mol/L,反应温度为85℃,液固比为5:1(m L/g),反应时间为2 h,在此适宜条件下,硒和碲的浸出率分别为82.49%和92.45%,金、铂和钯均未被浸出。氧化碱浸后渣中贵金属总含量达到23.18%,相对铂钯精矿富集6.35倍。

Effects of Calcium Sprays and Different Storage Treatment on the Preservation of Malus pumila Mill. Cv. ‘Jinguan’

Taking Malus pumila Mill, Cv. ‘Jinguan＇ as test matedal, the storage quality of the apples under the different storage conditions of plastic membrane atmosphere storage （MAP）, fruit wax coating, chitosan treatment with different calcium fertilizers were studied. The results showed that different storage modes inhibited the fruit rotting and weight loss, delayed the decrease of fruit hardness and titratable acid content, reduced the soluble solid content, inhibited the degradation of vitamin C. The suitable treatment had good effect on preservation of apple fruits, in which 1% chitosan treatment had the best effect.

STUDY OF Ti－Ni－Nb SHAPE MEMORYALLOY PIPE COUPLING

Ternary Ti-Ni-Nb alloys have wider transformation hysteresis than binary Ti-Ni alloys. In our experiment, Ti-Ni-Nb alloy was prepared by melting pure titanium , Pure nickel and pure niobium in a cold crucible in a magnertic suspension furnace under a controlled protective argon followed byquenching in an iron mould The hysteresis width under 16% pre-deformation is 155 C. The hydrostatic , tensile, torque, fattigue tests were conducted to evaluate the performance of the pipe coupling system.All the test results indicate excellent behavior and possible applications of Ti-Ni-Nb shape memory alloy in the future .

回收低浓度废液中贵金属的工业化研究

通过工业化试验得出,分铜后液中金、铂、钯的还原率均可以达到80%以上,还原后液中贵金属控制在0.2mg/L以下,还原渣中金、铂、钯总量均值在0.25%,每年可增效约361.2万元;沉金后液中金、铂、钯的吸附率均可以达到95%以上,与锌粉置换工艺对比,树脂吸附工艺在沉碲之前就将金、铂、钯等贵金属有效富集,避免了贵金属与碲混合,省去了贵金属与碲的分离工序;铂的回收率从60%提高到了95%,每年将为企业增加利润1 381.52万元。通过回收低浓度废液中贵金属,企业每年可以增加效益1 742.72万元。

Microstructure and mechanical properties of friction welds between TiA l alloy and 40Cr steel rods

Direct friction welding of Ti Al alloy to 40 Cr steel rods was conducted, and the microstructure and mechanical properties of the resultant joints in as-welded and post-weld heat treatment（PWHT） states were investigated. The martensitic transformation occurred and brittle Ti C phase formed near the interface due to C agglomeration, which degraded the joint strength and increased the microhardness at the interface in as-welded state. Feathery and Widmanstatten structure generated near the interface on Ti Al alloy side. After PWHT at 580 °C and 630 °C for 2 h, the sorbite formed and C dispersed at the interface, leading to the increase of the joint strength from 86 MPa in as-welded state to 395 MPa and 330 MPa, respectively. The heat-treated specimen fractured with quasi-cleavage features through the zone 1 mm away from the interface on TiA l alloy side, but the as-welded specimen failed through the interface.

THRESHOLD STRESS INTENSITIES FOR HYDROGEN-INDUCED DELAYED FAILURE OF WELD METAL OF AUSTENITIC STAINLESS STEEL

It was found that hydrogen induced delayed failure could occur in 308L and 347L weld metals,and the threshold stress intensities of 308L and 347L welds were lower than that of 304L austenitic stainless steel.When dynamically charged under load on a single edge notched specimen,the threshold stress intensities of 308L,347L and 304L decrease with the increase in the diffusible hydrogen content C 0 and the experimental results are as follows:K ⅠH =85.2-10.7 ln C 0 (308L),K ⅠH =76.1-9.3 ln C 0 (347L),K ⅠH =91.7-10.1 ln C 0 (304L).The morphology of the hydrogen induced delayed fracture in the three materials are correlated with the K Ⅰ and C 0 values.

Amine-grafted on lanthanide metal-organic frameworks:Three solid base catalysts for Knoevenagel condensation reaction

A post-synthetic modification strategy has been used to prepare three solid base catalysts, including Er（btc）（ED）075（H2O）0.25 （2, btc = 1,3,5-benzenetricarboxylates, ED = 1,2-ethanediamine）, Er（btc）（PP）0.55（H20）0.45 （3, PP = piperazine）, and Er（btc）（DABCO）0.15（H2O）0.85 （4, DABCO = 1,4- diazabicyclo[2.2.2]octane）, by grafting three different diamines onto the coordinatively unsaturated Er（III） ions into the channels of the desolvated lanthanide metal-organic framework （Er（otc））. The resulting metal-organic frameworks were characterized by elemental analysis, thermogravimetric analysis, powder X-ray diffraction, and N2 adsorption. Based on its higher loading ratio of the diamine, as well as its greater stability and porosity, catalyst 2 exhibited higher catalytic activity and reusability than catalysts 3 and 4- for the Knoevenagel condensation reaction. The catalytic mechanism of 2 has also been investigated using size-selective catalysis tests.

Selection of reductants for extracting selenium and tellurium from degoldized solution of copper anode slimes

This paper focused on investigating high-efficient reductants of recovering selenium and tellurium from degoldizedsolution of copper anode slimes.Firstly,the effect of various reductants on recovery rates of Se and Te was investigated based onthermodynamic analysis of various metallic ions in degoldized solution.Secondly,the single factor experiments were made toinvestigate the effect of the process parameters on recovering Se and Te with hydrazine hydrate.Finally,the hydroxylaminehydrochloride was added to intensify the extraction efficiencies of Se and Te.The results indicated that hydrazine hydrate was themost suitable reductant,and the recovery rates of Se and Te are71.23%and76.50%,respectively;the recovery rates of Se and Tewere92.07%and97.81%,respectively,under the optimal process conditions of hydrazine hydrate dosage of0.2133mol/L,H+concentration of4.305mol/L,reaction temperature of85°C and reaction time of5h;the recovery rate of Se was97.59%,and that Tereached up to100%when hydroxylamine hydrochloride dosage was1.5116mol/L.

Effect of heat treatment conditions on ballistic behaviour of various zones of friction stir welded magnesium alloy joints

Ballistic behaviour of different zones of post-weld heat-treated(PWHT)magnesium alloy(AZ31B)target against 7.62 mm×39 mm armour-piercing(AP)projectile with a striking velocity of(430±20)m/s was determined.Magnesium alloy(AZ31B)welded joints were prepared by using friction stir welding(FSW)process and subjected to different heat treatment conditions.The microhardness values of non-heat-treated and heat-treated FSW joints were investigated.The results indicated that PWHT process(250°C,1 h)has improved the microhardness of heat-treated FSW joints.Scanning electron microscope(SEM)microstructure showed that heat treatment has caused the formation of fineα-Mg grains and tiny precipitates and made the dissolution ofβ-Mg17Al12 phase into the Mg matrix.The ballistic behaviour of PWHT zones was estimated by measuring the depth of penetration(DOP)of the projectile.Lower DOP value was observed for the base metal zone(BMZ)of a heat-treated welded joint.Post ballistic SEM examinations on the cross-section of all three zones of crater region showed the formation of adiabatic shear band(ASB).

Effect of post weld heat treatment on properties of variable polarity TIG welded AA2219 aluminium alloy joints

AA2219 aluminium alloy joints were fabricated by variable polarity tungsten inert gas （VPTIG） welding process and the effects of post weld heat treatment （PWHT） on the tensile properties, microstructure and fatigue behaviour of the welded joints were investigated. The VPTIG welding process was adopted because it could meet the need of cathode cleaning and meanwhile it could reduce the deterioration of tungsten electrode furthest. The welded samples were divided into as-welded （AW） sample and PWHT sample. The PWHT method used on the samples was solution treatment （535 ℃, 30 rain）, water quenching and artificial aging （175 ℃, 12 h）. The experimental results show that, compared with the AW samples, the microstructure characteristics and mechanical properties of the AA2219 joints after PWHT were significantly improved. The improvement of yield strength, ultimate tensile strength, and fatigue strength are 42.6%, 43.1% and 18.4%, respectively.