Tomas Havlik

Leaching of copper and tin from used printed circuit boards after thermal treatment

The hydrometallurgical route of copper and tin extraction from printed circuit boards (PCBs) of used personal computers after thermal pretreatment is discussed. The samples were thermally pretreated within temperature range of 300-900°C during 15, 30 and 60 min. Two methods of the thermal pretreatment were studied: burning and pyrolysis. The leaching solution of 1 M HCl at 80°C was used. The original as well as thermally pretreated samples were leached. The weight losses within the range from 5 to 35% were achieved. The increase of burning temperature causes the copper extraction into solution up to 98%, while copper extraction into solution from non-burned samples was up to 6%. In the case of the tin leaching the highest extraction was achieved when the original sample was leached. The increase of the burning temperature caused the lowering of the copper extraction. The increase of the pyrolysis temperature enhances copper and tin extraction.

Acidic leaching both of zinc and iron from basic oxygen furnace sludge.

During the steel production in the basic oxygen furnace (BOF), approximately 7-15 kg of dust per tonne of produced steel is generated. This dust contains approximately 1.4-3.2% Zn and 54-70% Fe. Regarding the zinc content, the BOF dust is considered to be highly problematic, and therefore new technological processes for recycling dusts and sludge from metallurgical production are still searched for. In this study the hydrometallurgical processing of BOF sludge in the sulphuric acid solutions under atmospheric pressure and temperatures up to 100 °C is investigated on laboratory scale. The influence of sulphuric acid concentration, temperature, time and liquid to solid ratio (L:S) on the leaching process was studied. The main aim of this study was to determine optimal conditions when the maximum amount of zinc passes into the solution whilst iron remains in a solid residue.

Leaching of chalcopyrite with acidified ferric chloride and carbon tetrachloride addition

Abstract Leaching characteristics of chalcopyrite concentrate from Cuba were investigated in acidified FeCl 3 and acidified FeCl 3 + CCl 4 . Carbon tetrachloride was used as solvent for the elemental sulfur produced during leaching. The tests shows higher extraction for copper in the presence of CCl 4 . Leaching in the absence of CCl 4 is a chemically controlled reaction with an apparent activation energy of 68.9 kJ/mol in the temperature range 45–80°C. For the diffusional controlled regime in the low temperature range (3.5–45°C) an apparent value of the activation energy of 1.1 Kj/mol has been estimated. In the presence of CCl 4 the activation energy value amounts to 31.2 kJ/mol in the temperature range 45–80°C which indicates a diffusion controlled process.

Leaching of chalcopyrite concentrate with ferric chloride

Abstract In this study the kinetic leaching characteristics of chalcopyrite concentrate from Cuba (32.3% Cu) were investigated with granularities − 315 + 200 μm as delivered. The value of the apparent activation energy was determined to EA = 55 ± 5 kJ/mol, which is in agreement with published results. Microscopic and X-ray diffractometric investigations have confirmed that by measurement of real structure changes the assumed reaction chemism and the mechanism of chalcopyrite leaching can be observed.

Non-oxidative leaching of mechanically activated stibnite

Abstract The results obtained by leaching stibnite with a basic solution of sodium hydrogen sulphide are presented in this paper. The intensification of leaching by the mechanical activation produced by grinding the mineral in a planetary mill for 20 min brings about acceleration of the process by tenfold. The non-oxidative leaching of stibnite is a structure-sensitive process and the structure sensitivity decreases if assemblages of particles, i.e., agglomerates arise. The activation energy calculated from the temperature dependence of leaching in the region 293–345 K had the value E=28 kJ mol−1 for a non-activated sample (standard) and E=13 kJ mol−1 for a sample activated for 20 min. This suggests that the rate-determining step must have been changed. The SEM investigation of the residues after leaching documents the morphological non-uniformity of the leaching process.

Hydrometallurgical treatment of used printed circuit boards after thermal treatment.

The hydrometallurgical route of copper and tin extraction from printed circuit boards (PCB) of used personal computers after thermal pretreatment is discussed. The PCB fractions crushed and sorted into -8+0, -8+3 and -3+0 mm were used for the experiments. The samples were thermally pretreated at temperatures of 300, 500, 700 and 900 °C during 15, 30 and 60 min with the presence of air (burning) before the leaching process. The leaching solution of 1M HCl and temperature of 80 °C was used for the leaching. The original as well as thermally pretreated samples were leached under these conditions. The weight losses within the range from 5% to 35% were achieved by burning depending on the burning temperature. The increase of burning temperature causes the copper extraction into solution up to 98%, while copper extraction into solution from non-burned samples was up to 6%. The opposite effect was observed in the case of the tin leaching, where the highest extraction was achieved when the original sample was leached. The increase of the burning temperature caused the lowering of the copper extraction.

Submerged-arc welding slags: Characterization and leaching strategies for the removal of aluminum and titanium

In the present study, submerged-arc welding slags were characterized by applying a variety of methods, including X-ray fluorescence, X-ray diffraction, particle size, Raman spectroscopy, and scanning electron microscope with energy dispersive X-ray analysis. The content of Al proved to be quite similar within neutral and acid slags (10-14%), while that of Ti proved to be much higher in acid slags (approximately 10%) than in neutral slags (<1%). The presence of spinel structures associated with Al species could also be identified in the analyzed samples. This characterization study was accompanied by leaching tests performed under changing operating conditions in an attempt to evaluate to what extent the Al and Ti bearing components could be removed from the slags. The leaching work involved three distinct strategies: (i) NaOH leaching followed by H(2)SO(4) leaching, (ii) acid leaching (HCl and H(2)SO(4)) using oxidizing/reducing agents, and (iii) slag calcination followed by H(2)SO(4) leaching. In the best result, 80% of Al was extracted in one single leaching stage after calcination of the acid slag with NaCl+C at 900 °C. By contrast, the removal of Ti proved to be unsatisfactory.

Physical and chemical treatment of end of life panels: An integrated automatic approach viable for different photovoltaic technologies

Different kinds of panels (Si-based panels and CdTe panels) were treated according to a common process route made up of two main steps: a physical treatment (triple crushing and thermal treatment) and a chemical treatment. After triple crushing three fractions were obtained: an intermediate fraction (0.4-1mm) of directly recoverable glass (17%w/w); a coarse fraction (>1mm) requiring further thermal treatment in order to separate EVA-glued layers in glass fragments; a fine fraction (<0.4mm) requiring chemical treatment to dissolve metals and obtain another recoverable glass fraction. Coarse fractions (62%w/w) were treated thermally giving another recoverable glass fraction (52%w/w). Fine fractions can be further sieved into two sub-fractions: <0.08mm (3%w/w) and 0.08-0.4mm (22%w/w). Chemical characterization showed that 0.08-0.4mm fractions mainly contained Fe, Al and Zn, while precious and dangerous metals (Ag, Ti, Te, Cu and Cd) are mainly present in fractions <0.08mm. Acid leaching of 0.08-0.4mm fractions allowed to obtain a third recoverable glass fraction (22%w/w). The process route allowed to treat by the same scheme of operation both Si based panels and Cd-Te panels with an overall recycling rate of 91%.

Recovery of Copper and Tin from Used Printed Circuit Boards

This work focuses on possibilities to recover tin and copper by hydrometallurgical processes from printed circuit boards (PCBs) of discarded personal computers after thermal treatment. For experimental work crushed and sorted printed circuit boards with various granularity /-8 +0 mm, -8 +3 mm, -3 +0 mm/ were used. They were exposed to thermal treatment at temperatures 300 °C, 500 °C, 700 °C and 900 °C before leaching for 15, 30 and 60 minutes. The two thermal treatments were studied: in air flow, i.e. burning, and pyrolysis (without air flow). For leaching experiments 1M solution of HCl at 80 °C was used. Under the mentioned conditions both samples, the thermally treated sample of PCB as well as the original untreated printed circuit board, were leached with the aim to compare the experimental results. Weight losses during burning accounted for 5 to 35 %, while pyrolysis caused weight losses from 10 to 30 %, depending on the thermal treatment temperature. The higher the burning temperature, the higher the extraction of copper into the solution with up to 98%.However, extraction of copper from non-burned samples does not exceeded 6 %. An opposite effect has been observed during leaching of tin, where the highest extraction was reached using thermally untreated samples, and extraction decreased with an increasing burning temperature. With increasing pyrolysis temperature a higher extraction level was observed during leaching of copper and tin into the solution. The maximal extraction was reached with the leaching of thermally untreated samples, namely 6 % for copper and about 68 % for tin whereas the extraction of copper and tin achieved with thermally treated samples was 63 % and 98 %, respectively.

Process Kinetics Studied by X-Ray Diffraction

An analysis can be regarded as a process of changing the degree of uncertainty with respect to the unknown values. The goal of an analysis is then to gain a maximum decrease of uncertainty. This implies that the decrease of uncertainty also describes the inadequacy of the analysis and may be considered as a measure for the amount of information obtained1,2,3. X-ray diffraction is a very powerful analytical technique since it enables to obtain a lot of information on the structure of matter: its phase composition, molecular structure, and real structure. The information content of X-ray diffraction analytical techniques can further be extended when they are applied to the examination of processes.