Pan American Materials Congress: Minerals Extraction and Processing: Hydrometallurgical Processing
Sponsored by: Third Pan American Materials Congress Organizing Committee
Program Organizers: Mery Gómez Marroquín, Asociacion Peruana de Metalurgia Materiales y Minerales-APMMM; Mark Schlesinger, Missouri University of Science and Technology; Alejandro Valdivieso, U.A. of San Luis Potosi; Carlos Sampaio, UFRGS

Thursday 8:30 AM
March 2, 2017
Room: Marina E
Location: Marriott Marquis Hotel

8:30 AM  
Investigating the Dissolution Characteristics of Strontium Sulfide: İbrahim Göksel Hizli1; Ayşegül Bilen2; Raşit Sezer3; Emre Yilmaz2; Selim Ertürk2; Cüneyt Arslan2; 1Istanbul University; 2Istanbul Technical University; 3Karadeniz Technical University
    Celestite is the main source of strontium containing chemicals and metallic strontium. Unlike other sulfate containing minerals, celestite is not soluble in water. Further processing of SrSO4 requires to be converted to water soluble compound; strontium sulfide (SrS). In this study, solubility of SrS in distilled water is investigated. SrS used in experimental works obtained by roasting of celestite at 1100°C in lab scale rotary furnace. Experimental study carried out to determine the effects of time (90, 120, and 150 min), solid/liquid ratio (1/5, 1/10, and 1/25 w/v) and temperature (25, 55, 75 and 95°C). Stirring speed (500 rpm) and grain size of SrS (-54 μm) are used as constants. XRD results of leach cakes show that increasing temperature causes dissolution rate and efficiency to increase. On the contrary, increasing solid /liquid ratio decreases the leaching efficiency.

8:50 AM  
Dissolution Thermodynamics of Smithsonite in Alkaline Iminodiacetate Aqueous Solution: Dou Aichun1; Yu Lei1; 1Jiangsu University, China
    The thermodynamic model of the dissolution of smithsonite (ZnCO3) in alkaline iminodiacetate aqueous solution (Ida2--H2O system) was constructed according to the thermodynamic equilibrium equations in the system. Thermodynamic results of total concentration of Zn2+ ([Zn2+]T), free concentration of Zn2+ ([Zn2+]), free concentration of Ida2- ([Ida2-]), free concentration of CO32- ([CO32-]), species distribution of Zn2+ and species distribution of Ida2- changed with total concentration of Ida2- ([Ida2-]T) and pH value were investigated respectively at 298K. It is found that both [Ida2-]T and pH have significant effects on [Zn2+]T. [Zn2+]T increases in line with the increase of [Ida2-]T under the certain pH value. The optimal pH area for the dissolution of ZnCO3 in Ida2--H2O system is pH 8~11. In this area, [Ida2-]T increases smoothly with the increase of pH, above 90% of Ida2- is used for the formation of Zn(Ida)22-, and above 99% of Zn2+ is formed as Zn(Ida)22-.

9:10 AM  
Preparation of High Grade Industrial Copper Compound from a Nigerian Malachite Mineral by Hydrometallurgical Process: Alafara Baba1; Ruth Sanni1; Abdulrahman Abubakar1; Rafiu Bale1; Folahan Adekola1; Abdulganiyu Alabi1; 1University of Ilorin, Nigeria.
    Increasing demands for copper and copper sulphate with diverse industrial applications has prompted the development of a low-cost and eco-friendly technique as a substitute for conven-tional ore treatments by reduction-roasting route, requiring high energy consumption. In this study, hydrometallurgical treatment of a Nigerian malachite through acid leaching and solvent extraction was investigated. The effects of leachant concentration, reaction temperature and par-ticle size were examined. The rate of ore dissolution increased with increasing H2SO4 concentra-tion, temperature and decreasing particle size. At optimal leaching conditions, 96.2% of the ore reacted with 2.0 mol/L H2SO4 solution at 75 °C within 120 minutes. The calculated activation energy was 25.41 kJ/mol, supporting the proposed diffusion controlled mechanism for the disso-lution process. The leach liquor at optimal conditions was further beneficiated to obtain high grade industrial copper sulphate using a combinations of solvent extraction and precipitation methods, leading to 98% process efficiency.

9:30 AM  
Pressure Leaching of Hemimorphite in Ammonium Chloride Solution: Duoqiang Zhao1; Shenghai Yang1; Hao Li1; Yongming Chen1; Jing He1; Chaobo Tang1; 1Central South University
    The dissolution behavior of zinc from hemimorphite in ammonium chloride solution at high temperature(>100℃) was studied. The effect of temperature, ammonium chloride concentration, liquid to solid and leaching time were discussed. Temperature and concentration of ammonium chloride are the key reaction condition in the leaching process. The time required to obtain 83% percentage of extraction zinc is less than 30min. More than 97% of zinc can been leached out under the conditions of ammonium chloride concentration of 5.5mol/L, holding at 160℃ for 3h, the ratio (ml/g) of liquid to solid being 9 and stirring speed of 400rpm. XRD analysis was used to study the phase of hemimorphite and residue. Si was remained in residue as trigonal system α-quartz. Zinc was precipitated as Zn(NH3)2Cl2 as the temperature of lixivium cooled to room temperature. keywords: hemimorphite; ammonium chloride; pressure leaching

9:50 AM  
Gold Recovery from Waste Solutions of PCB Gold Plating Process using Hydro Cyclone Reactor for Demonstration Study: Mooki Bae1; Soo-kyung Kim2; Jae-chun Lee2; 1Korea University of Science and Technology; 2Korea Institute of Geoscience and Mineral Resources
    This paper presents a novel methodology to recover gold from waste solutions of printed circuit boards (PCBs) generated during the gold electro-plating. Studies have been carried out using two different sizes of hydrocyclone (339.06 mm and 357.14 mm height) at various parameters such as current, flow rate, electrolyte concentration, cathode materials, and anodic area to recover the gold. ~96% gold was recovered using short-corn type hydrocyclone (339.06 mm) at following conditions: applied current 17.4A, flow rate 3.98m/s, using stainless steel as cathode material. However, approximately same amount of gold can be also recovered with long-corn type hydrocyclone (357.14 mm). But, the possibility for damage of long-corn type hydrocyclone might be higher than short corn type hydrocyclone because reaction occurs only at small reaction surface area during gold recovery. Therefore, short corn type hydrocyclone has been considered for further study to recover gold.

10:10 AM Break

10:20 AM  
Leaching of Spent Ni-Mo Hydrodesulphurization (HDS) Catalyst in Oxalic Acid Solutions: Sedat İlhan1; 1Istanbul University
    In this work, the effect of crushing, temperature, oxalic acid concentration and stirring speed on the leaching of spent Ni-Mo HDS catalyst was investigated. Spent Ni-Mo HDS catalyst was roasted at 500 oC under dynamic air atmosphere for 4 h prior to leaching experiments. It was found that roasted spent Ni-Mo HDS catalyst included mainly Al2O3, MoO3, NiMoO4 and AlPO4. Leaching experiments were performed using 5 g of uncrushed roasted Ni-Mo HDS catalyst, 1 L of 0.25, 0.50, 0.75 and 1 M H2C2O4 solutions, 25, 40, 55 and 70 oC temperatures and 200, 250 and 300 rpm stirring speeds. Leaching behavior of Mo, Al, P and Ni was de-termined. It is seen that H2C2O4 can be used successfully for the leaching of roast-ed HDS catalyst. More than 90 % of the molybdenum and 80 % of Nickel is ex-tracted from the experiments carried out using 300 rpm stirring speed, 1 M H2C2O4 and 40 oC.

10:40 AM  
Working Experience with the New WOX Plant to Treat Zinc Waelzoxide at ZGH Boleslaw SA, Poland: Angel Selke1; Leszek Stencel2; Miroslaw Fatyga2; Bogdan Pieczonka2; Lukasz Zieba2; 1ingenium GmbH; 2ZGH Boleslaw SA
    The new facility for washing and leaching of 100.000 tpy of WOX (zinc waelzoxide) with a high content of chlorine and fluorine, was put into service at the end of March 2013. The process technology of removing chlorine and fluorine is made of two stages of continuous washing. The first step - is a counter-current washing of WOX at atmospheric pressure and the second stage is the high pressure washing. Second stage washing is carried out at the pressure of about 2 bar and temperature 120 °C, in an autoclave. The next step of the process is leaching of washed WOX with spent electrolyte coming as a feedback from existing Cell House. After separation and filtration the zinc sulphate solution is directed to the existing neutral leaching section. The final level of chlorine and fluorine are Cl <0.005%, and F <0.01%.

11:00 AM  
Synthesis of AgCN Nanowire Membranes in Aqueous Solutions from Silver Dicyanide Ions: Armando López-Miranda1; Gonzalo Viramontes-Gamboa1; Alejandro López Valdivieso2; 1Universidad Michoacana de San Nicolás de Hidalgo; 2Universidad Autónoma de San Luis Potosí
    Silver cyanide (AgCN) is a water insoluble polymer. When synthesized in aqueous solutions spontaneously forms rod-like colloids 700 nm length and 150 nm diameter. These colloids grow forming nanowires up to 5 um long and 700 nm diameter precipitating as a white powder. This work reports the synthesis of AgCN nanowires membranes up to 4 nm diameter and various mm long. Silver dicyanide ions were used as precursors and the surfactant dodecylsulfate as an active agent to decrease the diameter, increase the length of the nanowires and promote the formation of macroscopic membranes. Scanning and transmission electron microscopy showed that the AgCN macrostructures were constituted by nanowires embedded with nanoparticles. X-Ray Diffraction revealed that both AgCN membranes and colloids have the same crystal structure. FTIR spectroscopy indicated the presence of dodecylsulfate in the membrane. Assays by atomic emission spectroscopy showed that the silver nanowire yield was ~ 80 %.

11:20 AM  
Study on Leaching Valuable Elements from Bayan Obo Tailings: Bo Zhang1; Xiangxin Xue1; He Yang1; Xiaowei Huang1; Jianxin Han1; 1Notheastern University
     After extracting rare earth minerals, iron minerals and fluorite from Bayan Obo ore, niobium and scandium which are riched in the mineral processing tailings coexist with the remaining rare earth. In order to recovery these valuable elements, the tailings was disposed with the method of activating roasting-leaching. The tailings was roasted with NaCl-Ca(OH)2 under a temperature of 900℃ for 1.5h. Weight percentages of NaCl-to-tailings and Ca(OH)2-to-tailings are all about 10%. Then the roasted ore experienced two leaching stages from “hydrochloric acid pre-leaching at 90℃ for 1.5h” to “intensified sulfuric acid leaching at 300℃ for 1h”. The results show that, the leaching rates of niobium, scandium and rare earth in roasted ore could reach 86.80%, 97.42% and 97.94% respectively under the conditions above. Moreover, the radioactivity per unit mass of leaching residue was reduced to 745Bq/kg and environmentally friendly.