OPTIMIZATION OF LEACHING OF COPPER FROM OXIDIZED COPPER ORE IN NH3-(NH4)2SO4 MEDIUM

Studies were carried out for selective leaching of Cu with simultaneous avoidance of iron dissolution during leaching of oxidized copper ore in an aqueous NH₃-(NH₄)₂SO₄ system. The effects of leaching parameters, such as ammonia concentration, ammonium sulphate concentration, leaching time, and solid-to-liquid ratio, were investigated on leaching of copper. A 2ⁿ factorial experimental design method in the dissolution experiments was used. In addition, the “Steepest Ascent” method was also applied to determine the optimum leaching conditions. It was observed that the most effective parameters on the leaching of copper were ammonia concentration and leaching time. Only 0.17% of iron in ore was dissolved in ammonia and ammonium sulphate medium. The optimum conditions established for maximum copper recovery were: ammonia concentration 2.824 mol L^-1, ammonium sulphate concentration 0.236 mol L^-1, solid-to-liquid ratio 0.167 g mL^-1, leaching time 2 h. Fixed parameters chosen in the experiments were: room temperature, average particle size 2.8 mm, stirring speed 500 rpm. Under the optimum conditions established for maximum copper recovery, the percentage of leached copper was 98.87.     

EVALUATION OF LEACHING CONDITIONS FOR DISSOLUTION OF PYRITE IN CHLORINE-SATURATED WATER

The optimum leaching conditions for the dissolution of pyrite in water saturated with chlorine gas were investigated. Reaction temperature, solid-to-liquid ratio, reaction time, and particle size were selected as the leaching parameters. 2ⁿ factorial experimental design and orthogonal central-composite design methods were used. A mechanical stirring speed of 500 rpm and chlorine gas-flow rate of 1379 mL/minute were chosen as the fixed parameters in all experiments. The degrees of effectiveness from high to low were found to be, in respective order, the particle size, the reaction temperature, the solid-to-liquid ratio, and leaching time. A reaction temperature of 30°C, solid-to-liquid ratio of 0.167 g/mL, particle size of 150–212 μm, and reaction time of 360 minutes were found to be the optimum leaching conditions. The dissolution yield of iron from pyrite was 98.4% under optimal leaching conditions.     

(NH4)2SO4作助熔剂对单氟磷酸钠合成的影响

以六偏磷酸钠和氟化钠为合成单氟磷酸钠的主要反应原料,根据助熔剂的性质,筛选出(NH4)2SO4为较佳助熔荆.采用单因素实验法考察了干燥温度、干燥时间、合成温度、合成时间、氟磷比、n[(NH4)2SO4]:n(NaPO3)6+NaF]对反应的影响.通过正交实验优选,确定了最佳工艺条件.     

PRECIPITATION CONDITIONS OF CHEVREUL'S SALT FROM SYNTHETIC AQUEOUS CuSO4 SOLUTIONS

In this study, synthetic aqueous CuSO₄ solution was prepared at various concentrations. Chevreul's salt was precipitated by passing SO₂ through these solutions. Chevreul's salt, a mixed valence copper sulfite, Cu₂SO₃·CuSO₃·2H₂O, was characterized by XRD and SEM. The effects of parameters such as initial solution concentration, SO₂ feeding rate, reaction time, and initial solution pH on precipitation of Chevreul's salt were investigated. 2ⁿ factorial experimental design and orthogonal central composite design methods in the precipitation experiments were used. It was observed that the effective parameters on the precipitation of Chevreul's salt were initial solution concentration, SO₂ feeding rate, and initial solution pH. The optimum conditions obtained for maximum copper precipitation were: initial solution concentration 1.14 M, SO₂ feeding rate 329.35 L.h.^?1, reaction time 25 min, and initial solution pH 8.5. Constant parameters chosen at the initial stage of the reaction were: temperature 62°C, stirring speed 600 rpm, and reaction pH 3 (Çalban et al., 2006). Under these optimum conditions, the percentage of precipitated copper from synthetic aqueous CuSO₄ solutions was 99.95.     

OPTIMIZATION OF PROCESS PARAMETERS IN THE PRODUCTION OF MULLITE FIBERS VIA INVISCID MELT-SPINNING (IMS)

Process parameters for the formation of mullite fibers by the Inviscid Melt Spinning process were determined using a factorial design analysis. Mullite fibers were produced from a 3:2 mullite melt (M.P. = I830°C) via Inviscid Melt-Spinning (IMS) in a BN crucible, under an argon atmosphere, at a melt temperature of 2000°C and spinning pressure of 40psi. A heating rate-holding time program of 80°/min and 8 minutes, respectively, was used for the fiber-making experiment.     

SIMULTANEOUS ABSORPTION OF AN ACID GAS (H2S) AND A BASIC GAS (NH3) IN A SCRUBBING DEVICE

H₂S and NH₃ are major contaminants in many synfuel process gas streams. The H₂S is frequently removed by dissociation and reaction in scrubbers using alkaline scrubbing liquids. Some of the NH₃ is removed by simple dissolution in the same unit; the remaining NH₃ can be removed in a second scrubber using a mildly acidic liquid. The first scrubbing stage in such a system is novel in that an acidic gas (H₂S) and a basic gas (NH₃) are absorbed simultaneously. In this paper, the interesting behavior of this simultaneous acid gas-basic gas scrubbing process is described and discussed. The percentage H₂S and NH₃, absorption as a function of the injected liquid pH, the liquid-to-gas ratio, and the NH₃ content of the gas stream have been determined.     

298K时(NH_4)_2S_2O_3-(NH_4)_2SO_4-H_2O三元体系相平衡研究

通过改良合成复体法对(NH4)2S2O3-(NH4)2SO4-H2O三元体系在298 K下的溶液相平衡进行研究。利用X-射线粉末衍射法(XRD)表征平衡固相组成。结果证实:该方法能很好地用于(NH4)2S2O3-(NH4)2SO4-H2O三元体系平衡固相组成的分析。依据水、硫酸铵及硫代硫酸铵组成的饱和溶液各组分的质量分数绘制了(NH4)2S2O3-(NH4)2SO4-H2O在298 K下的三元体系相图。依据三元体系相图,结果显示:硫代硫酸铵的结晶区远远大于硫酸铵的结晶区,同时在该温度下,硫代硫酸铵、硫酸铵及水形成简单三元体系,体系中没有水合物形成。     

氨法脱硫中的氨逃逸和硫酸铵气溶胶现象

分析在氨法脱硫工程中出现氨逃逸和硫酸铵气溶胶的机理,提出防止或减轻氨逃逸和硫酸铵气溶胶现象的办法。     

Preparation of synthetic rutile via selective sulfation of ilmenite with (NH4)2SO4 followed by targeted removal of impurities

This paper describes a novel, facile chemical pathway for preparing synthetic rutile from ilmenite. The pathway consists of two primary units, i.e., selectively sulfating ilmenite, which was realized via roasting ilmenite with(NH_4)_2SO_4followed by selective thermal decomposition of the sulfated ilmenite, and targeted leaching of the impurities. The effects of the process parameters were systematically investigated. The results showed that the optimum sulfation conditions were a mass ratio of(NH_4)_2SO_4to ilmenite of 14, temperature of 360 °C, and time of 120 min with a sulfation ratio of ~ 95%. The optimum thermal decomposition conditions were480 °C in N_2 atmosphere, and nearly all Ti OSO_4 were decomposed with co-decomposition of Fe SO_4 of 23%. For acid leaching, the optimum conditions were 2.5 wt% HCl, 98 °C and 120 min. Under those conditions, 94.2% iron was removed with a Ti O_2 dissolution loss b 1%. For alkali leaching, 67% Si O_2 was removed in 5 wt% Na OH at102 °C for 1 h. A synthetic rutile with a Ti O_2 content N 92 wt% and total Mg O + Ca O b 1.5 wt% was obtained.Based on these results, a schematic flowsheet was proposed. Additionally, it was found that the decomposition of Fe SO_4 mixed with Ti OSO_4 under N_2was inhibited due to its oxidation to a higher thermal stability Fe_2(SO_4)_3by oxygen emitted from the decomposition of Ti OSO_4. At the same time, Ti OSO_4 decomposition was promoted due to the immediate in situ consumption of oxygen by Fe SO_4. The synergetic effect might be responsible for the enhanced selectivity of sulfated ilmenite thermal decomposition.     

The Effect of Ultrasound on the Dissolution of Pyrite Ores in Acidic and Fe2(SO4)3 Solutions

This paper deals with the investigation of the effect of ultrasonic energy on the dissolution of pyrite ores in acidic and Fe₂(SO₄)₃ solution. In the effect of ultrasound on the dissolution at various temperatures was experimentally investigated, while keeping the particle size and the solution concentration constant. The same experimental runs, without using ultrasound, were performed and the results were compared. According to these results, it was observed that ultrasound increased the conversion fraction by approximately 30 % compared with the experimental results without ultrasound.     

低品位钼镍焙烧矿常压同时浸出钼镍的工艺研究

以低品位的钼镍矿石为原料与CaO混合高温焙烧,所得焙烧矿采用常压氨-碳铵浸出,对同时浸出镍和钼的工艺条件进行了研究。探讨了温度、液固比、浸出时间、碳酸铵的用量等因素对钼和镍浸出率的影响。结果表明,在浸出温度45℃,液固比4∶1(mL/g),浸出时间24h,碳酸铵用量w((NH4)2CO3)∶w(焙烧矿)=0.3的最佳浸出条件下,钼和镍的浸出率分别为94.0%和90.1%。     

从稀土矿泥氯化焙烧浸取液制备晶态碳酸稀土

以碳酸氢铵为沉淀剂,通过正交试验确定了从川西稀土矿泥氯化焙烧水浸液中制备晶态碳酸稀土的最佳制备条件．讨论了碳酸氢铵在沉淀过程中的作用、析出碳酸稀土的最低pH值、过饱和度及外加（NH4）2SO4等对晶态碳酸稀土生成的影响．经化学分析、X射线衍射及电镜确认制备的为条形晶态碳酸稀土．     

SnO_2-高岭土负载硫酸镓催化合成己酸己酯

SnC l4.5H2O和高岭土的质量比1∶3,饱和Ga2(SO4)3溶液浸渍4 h,300℃焙烧2 h,制备了以Ga2(SO4)3为活性组分、SnO2-高岭土为载体的负载型酯化催化剂。用于正己酸与正己醇合成己酸己酯酯化反应,考察了催化剂用量、n(正己醇)∶n(正己酸)、反应时间、带水剂种类及用量等因素对酯化率的影响。结果表明,合成己酸己酯的适宜反应条件为:n(正己醇)∶n(正己酸)=1.4,苯15 mL,催化剂用量为反应物总质量的3.0%,反应时间100 min,酯化率为98.8%。该催化剂催化活性高、成本低、制备方法简单,并且易分离回收。     

沸石对重金属废水中Cu(HN_3)_4~(2+)的吸附性能研究

利用沸石吸附法去除重金属废水中以络离子形态存在的铜。实验考察了沸石用量、振荡时间、p H和温度对吸附效果的影响 ,探讨了吸附作用机理。结果表明 ,沸石对 Cu( HN3 ) 2 + 4 有良好的吸附性能 ,废水 p H、温度和吸附时间是影响吸附效果的主要因素。在 Cu( HN3 ) 2 + 4 浓度低于 5 0 mg/L时 ,吸附规律基本符合 Freundlich模式 ,高于 5 0 mg/L时 ,不能满足常规吸附规律     

298 K时三元体系MeSO4-(NH4)2SO4-H2O的相平衡

用等温溶解平衡法研究了298 K时MeSO4-(NH4)2SO4-H2O三元体系的溶解度,并绘制了平衡相图. 结果表明,在MnSO4-(NH4)2SO4-H2O体系中,有MnSO4×H2O, (NH4)2Mn(SO4)2×6H2O和(NH4)2SO4 3条饱和曲线,组成为MnSO4×H2O和(NH4)2Mn(SO4)2×6H2O及(NH4)2Mn(SO4)2×6H2O和(NH4)2SO4的2个共饱和点,以及平衡固相为(NH4)2SO4, (NH4)2Mn(SO4)2×6H2O和MnSO4×H2O的3个纯盐结晶区. 在ZnSO4-(NH4)2SO4-H2O体系中,有(NH4)2Zn(SO4)2×6H2O, ZnSO4×7H2O与(NH4)2SO4 3条饱和曲线,组成为(NH4)2Zn(SO4)2×6H2O和ZnSO4×7H2O及(NH4)2SO4和(NH4)2Zn(SO4)2×6H2O的2个共饱和点,以及平衡固相为(NH4)2Zn(SO4)2×6H2O, ZnSO4×7H2O和(NH4)2SO4的3个纯盐结晶区. 在(NH4)2SO4-FeSO4-H2O体系中,有(NH4)2Fe(SO4)2×6H2O, FeSO4×7H2O和(NH4)2SO4的3条饱和曲线,组成为(NH4)2Fe(SO4)2×6H2O和FeSO4×7H2O及(NH4)2Fe(SO4)2×6H2O和(NH4)2SO4的2个共饱和点,以及平衡固相为(NH4)2Fe(SO4)2×6H2O, FeSO4×7H2O和(NH4)2SO4的3个纯盐结晶区. 研究结果既为含Fe2+, Mn2+和Zn2+溶液的复盐沉淀深度净化提供了理论指导,同时也为四元体系的研究奠定了基础.     

低浓度下己内酰胺-水-硫酸铵-苯体系的液液平衡问题

介绍了在己内酰胺废水中萃取回收己内酰胺的过程中，测定了4套己内酰胺—水—硫酸铵—苯体系的液液平衡数据(水相己内酰胺质量分数小于13％)。实验结果表明，用苯从废水中萃取回收己内酰胺时，pH在2～5．7范围内，pH值升高对回收有利。同时提出了一个简单的关联式并成功地关联上述平衡数据，已用于萃取塔的设计计算。     

固载硫酸盐Ga_2(SO_4)_3/SnO_2-高岭土的制备及其催化合成乳酸丁酯

制备了以Ga2(SO4)3为活性组分、SnO2-高岭土为复合载体的酯化催化剂Ga2(SO4)3/SnO2-高岭土,利用IR、XRD测试技术表征了催化剂的物化性质;并将该催化剂用于乳酸与正丁醇进行酯化反应合成了乳酸丁酯,考察了催化剂制备条件(浸渍时间和焙烧时间)、催化剂用量、n(正丁醇)∶n(乳酸)、反应时间及催化剂重复使用性等因素对酯收率的影响。结果表明,该催化剂催化活性高、成本低、制备方法简单并且易分离回收。催化剂的适宜制备条件是SnCl4.5H2O和高岭土的质量比1∶3、饱和Ga2(SO4)3溶液浸渍4 h、300℃焙烧2 h。该催化剂催化合成乳酸丁酯的适宜反应条件为:n(正丁醇)∶n(乳酸)=1.6、催化剂用量为反应物总质量的2.5%、反应时间3.5h。在此条件下,酯收率为95.3%。催化剂使用4次后,酯收率仍可达90%以上。     

固体超强酸SO~（2－）_4／ZrO_2催化合成偏苯三酸三（2－乙基）己酯

采用固体超强酸催化剂ＳＯ２－４／ＺｒＯ２催化合成偏苯三酸三（２ 乙基）己酯，考察了催化剂制备条件对催化活性的影响，探讨了催化剂用量、原料配比、反应时间等因素与酯化深度的关系，确定了最佳工艺参数。     

钙碳比对CaSO4-CaCO3-(NH4)2CO3-H2O体系反应-结晶过程的影响

在CaSO₄-CaCO₃-（NH₄）₂CO₃-H₂O反应体系中,生成碳酸钙与硫酸铵的控速步骤是石膏溶解。溶解表面被新生的碳酸钙结晶覆盖是重要影响因素。基于反应面模型,通过调整钙离子溶出速率与碳酸根加入速率之比（钙碳比）,将反应-结晶面控制在溶解表面的固液扩散边界层临界距离之外从而避免覆盖。实验采用表面积一定的天然纯净块状石膏试样,并向溶解体系滴加碳酸铵溶液,使钙碳比分别为0.125、0.25、0.5、1、2、4和8,观察碳酸钙在石膏表面的包覆现象,并预测反应-结晶面与溶解表面之间的微距离。结果显示,当钙碳比为0.125、0.25、0.5和1时,试样表面出现碳酸钙包覆但包覆量随λ增大而减小;当钙碳比为2、4和8时,试样表面不出现包覆,碳酸钙结晶生成于液相主体。将钙碳比为1视为临界值,该条件下反应-结晶面与溶解表面的微距离大于18 μm。     

THE EXTRACTION OF COBALT(II) FROM A THIOCYANATE MEDIUM BY SOME DIAMINE AND MONOAMINE EXTRACTANTS DISSOLVED IN 5% ISODECANOL - BENZENE

The tertiary amine extractants N,N,N’,N’-tetra-n-octylethylenediamine, N,N-di-n-octyl-2-(aminomethyl)pyridine and Alamine 336 were used to extract cobalt(II) from a thiocyanate medium. The extraction equilibria were identified and the extraction constants for these equilibria are presented.

Thiocyanic and sulphuric acid extraction was investigated. The protonation constants of the tertiary amines with these acids are reported.

The potential of the chelate mode, displayed by tertiary diamine extractants, was evaluated. The extraction properties of tertiary diamine extractants were demonstrated to be superior to a tertiary monoamine extractant, Alamine 336.