SEPARATION OF LEAD FROM DRY DROSS OF SnPb0,3 SOLDER FROM PT TIMAH INDUSTRI BY SELECTIVE LEACHING OF LEAD USING NITRIC ACID

• Main Author: AHMAD RUSTANDI (NIM : 12514026), RENDI
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/30309
• Institution: Institut Teknologi Bandung

Tin is one of non-ferrous metals that has been used in several industrial sectors such as electronic equipment, food packaging material, construction, and vehicle. Based on the data from International Tin Association (ITA) and International Tin Research Institute (ITRI), the demand of tin increases in recent years. PT Timah Industri is a subsidiary of PT Timah which plays role in downstream industry of tin and produces tin chemical and tin solder. There are several types of solder produced by PT Timah Industri, one of them is SnPb0.3 solder. Production of solder produces dross as byproduct. In PT. Timah Industri plant, dross is collected and re-melted to produce new solder product. This processing of dross results in the second dross which is called dry dross. At the moment, the dry dross of PT. Timah Industri is still stored in a storage building and not yet being beneficiated. This solder dry dross typically contains 92.9% Sn and 1.08% Pb. A study is required to separate Pb from dry dross and to recover tin from the dry dross. <br /> <br /> In this research, separation of lead from tin in dry dross by selective leaching of lead using nitric acid is performed. At first, size reduction was made to obtain dry dross sample with particle size distribution of -200 mesh. Series of agitation leaching experiments at atmospheric pressure have been carried out to study the effect of the concentration of nitric acid, solid/liquid ratio (g/ml) and temperature on lead separation percentage and final dissolved tin percentage. The best condition is achieved when maximum lead separation and minimum dissolved tin were obtained. Concentrations of dissolved Sn and Pb were measured by AAS analysis. XRD analysis was carried out to identify the most dominant compound present in the leaching residue, while chemical composition of the leaching residue was determined by XRF analysis. <br /> <br /> The experimental results showed that the leaching of dry dross using nitric acid can selectively dissolve lead and produces tin-rich residue. The best leaching condition was obtained at 4 M nitric acid, room temperature, 1:10 solid/liquid ratio, and stirring rate of 380 rpm for 24 hours. At this condition, the separation percentage of lead was 99.78% with final dissolved of tin only 0.04%. The value of lead leaching selectivity to tin at this condition was 0.9996 (0-1 scale). The analysis of XRD and XRF of the leaching residue showed the content of tin and lead 97.69% and 0.0372% respectively in which tin was found in the form of tin oxide (SnO2).