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Recovery of base and precious metals from scrap TV boards using zig-zag air separator

Yazici Ersin Yener, Celep Oktay, Ibrahim Boulama Omar Yacine Lawan, Deveci Haci

Physicochemical Problems of Mineral Processing

2023

Vol. 59, iss. 5

art. no. 168255

Waste of Electrical and Electronic Equipments (WEEE) is one of the fastest growing waste streams in the world. The treatment of WEEE with high content of precious metals (Au in particular) has received the most attention due to their high economic potential. The development of simple, environmentally friendly and cost-effective methods for the recovery of metals from “low-value” WEEE (e.g., <100 g/t Au) is important from the circular economy perspective. In this study, the separation of base (Cu) and precious (Ag) metals from scrap TV boards (STVBs) by using a zig-zag air separator was investigated. Size-reduced scrap STVBs (-1 mm) were subjected to separation tests after the removal of the fine fraction (-0.1 mm). The sized scrap material (-1 +0.1 mm) was determined to have a metal content of 15.4% Cu, 47 g/t Ag and 0.05% Fe, with no gold. In the air separation tests, the effect of air flow rate (4-16 m/s) on the recovery of metals was studied. Increasing the air flow rate resulted in low metal recoveries with concurrent high metal grades in the concentrate. Separation efficiency (%) calculations showed that the most efficient separation is obtained at the highest air flow rate of 16 m/s. At this flow rate, 15.4% of the material was recovered in the concentrate which contains 62.3% Cu and 198 g/t Ag with recoveries of 63.3% Cu and 73.9% Ag. The findings indicated that zig-zag air separators can be used to obtain a metal-rich fraction under suitable conditions of the flow regime.

Effects of lead nitrate and pre-aeration on the deportment of base/precious metals in cyanide leaching of a pyritic refractory gold concentrate

Deveci Hacı, Yazıcı Ersin Yener, Celep Oktay, Mercimek Murat, Demirel Cumhur, Çakmak Serkan, Cingöz Melih Baki, Kavlu Ömer Hami, Kömürcü Hüseyin

Physicochemical Problems of Mineral Processing

2023

Vol. 59, iss. 5

art. no. 166259

This study was undertaken to improve gold and silver extraction from a pyritic gold flotation concentrate, which assayed 11 g/t Au, 42 g/t Ag, 0.21% Cu, 3.57% Zn, and 31% Fe. Direct cyanide leaching of the concentrate at 1.5 g/L NaCN yielded a low gold extraction (37%), confirming its refractory nature. Effects of lead nitrate (200-500 g/t Pb(NO3)2) and pre-aeration (24 h) before cyanide leaching at 1.5-3.5 g/L NaCN were investigated. Earlier studies have focused on the impact of these parameters on gold leaching. Besides gold, this study demonstrated the behaviour of silver and base metals (copper and zinc) from the pyritic gold concentrate. Adding lead nitrate had a negligible effect on gold extraction whilst improving silver extraction. Dissolution of copper was substantially suppressed by adding lead nitrate, i.e., from 23% (no Pb(NO3)2) to 4% (500 g/t Pb(NO3)2) over 24 h. Zinc dissolution was negligible (≤0.01%). Pre-aeration of the concentrate improved the gold and silver extractions by 4-14% and 23-44% at the subsequent cyanide leaching (1.5-3.5 g/L NaCN). However, it did not affect the leaching of copper. Only negligible leaching of zinc (≤0.6%) occurred during cyanide leaching. Pre-aeration also reduced cyanide consumption in subsequent cyanide leaching (1.5 g/L NaCN), i.e., from 2.83 kg/t to 2.03 kg/t NaCN per solids. These results suggested that lead nitrate can improve silver extraction while suppressing copper dissolution, which would be advantageous in the leaching-adsorption circuit (CIP), mitigating the dissolved copper-associated problems. Pre-aeration can also be suitable for improved gold/silver extractions and reduced reagent consumption.

Surface Characterization of Oleic Acid Coated Marble Dust

Polat Ercan, Guler Taki, Celep Oktay, Akturk Selçuk

Inżynieria Mineralna

2020

no. 1, vol. 1

125--129

Calcite, being the most abundant mineral on earth crust, have wide application areas especially in polymer industry as a micronized functional filler material. It is hydrophilic in natural form, and made hydrophobic after surface modification to meet the requirements of polymer industry: the incompatibility between high energetic hydrophilic surface of calcite and the low-energy surface of hydrophobic polymers is a major problem. Treatment of micronized calcite with fatty acids is one of the most common method to obtain modified mineral surface. In present study, oleic acid (OA), fatty acid type surface modifying agent was used for the surface characterization of OA coated marble dust. Fine tailings of slab cutting unit of a marble processing plant was supplied. The sample was subjected to wet classification process to obtain micronized calcite fraction for experimental works. Surface modification of finely sized fraction was performed in a laboratory type flotation unit. Thermogravimetric analysis (TGA) and Transmission Electron Microscopy (TEM) were used as characterization techniques.

Kalcyt, będący najczęściej występującym minerałem w skorupie ziemskiej, ma szerokie obszary zastosowań, szczególnie w przemyśle polimerowym, jako mikronizowany funkcjonalny materiał wypełniający. Jest hydrofilowy w naturalnej postaci, a po modyfikacji powierzchni stał się hydrofobowy, aby spełnić wymagania przemysłu polimerów: niekompatybilność między wysokoenergetyczną hydrofilową powierzchnią kalcytu a niskoenergetyczną powierzchnią hydrofobowych polimerów jest poważnym problemem. Obróbka mikronizowanego kalcytu kwasami tłuszczowymi jest jedną z najczęstszych metod uzyskiwania modyfikowanej powierzchni mineralnej. W niniejszym badaniu do charakteryzowania powierzchni pyłu marmurowego pokrytego OA - kwasem oleinowym (OA), jako środek modyfikujący powierzchnię użyto kwasu tłuszczowego. Do badań wykorzystano drobne odpady z urządzenia do cięcia płyt w zakładzie przeróbki marmuru. Próbkę poddano procesowi mokrej klasyfikacji w celu uzyskania mikronizowanej frakcji kalcytu do prac eksperymentalnych. Modyfikację powierzchni frakcji drobnej wielkości przeprowadzono w laboratoryjnej jednostce flotacyjnej. Jako do scharakteryzowana próbek zastosowano analizę termograwimetryczną (TGA) i transmisyjną mikroskopię elektronową (TEM).