Penelitian ini bertujuan untuk mendapatkan logam tanah jarang dari terak timah berdasarkan konsentrasi asam sulfat dan rasio padat-cair yang paling optimum pada proses pelindian asam. Penelitian ini melakukan variasi terhadap konsentrasi asam sulfat sebesar 4, 6, 8, dan 10 M, serta rasio padat-cair (S/L) sebesar 1:10 dan 1:15 g/mL. Perlakuan awal sampel terak timah, yaitu diayak untuk mendapatkan ukuran seragam ≤ 100 mesh, kemudian dipanaskan dengan furnace pada suhu 700°C, dilanjutkan dengan pelindian asam menggunakan asam sulfat. Pelindian asam dilakukan dengan bantuan magnetic stirrer pada suhu 40°C selama 30-180 menit dan ditentukan yield ekstrak unsur serium (Ce), niobium (Nb), dan total unsur logam tanah jarang berupa serium (Ce), lanthanum (La), neodymium (Nd), praseodimium (Pr), dan itrium (Y). Ekstrak hasil pelindian dikarakterisasi dengan uji ICP-OES (inductively coupled plasma - optical emission spectrometry) untuk mendapatkan kandungan logam tanah jarang pada setiap variasi waktu, konsentrasi asam, dan rasio padat-cair. Yield Nb tertinggi didapatkan pada pelindian dengan rasio S/L 1:10 g/mL dengan konsentrasi 8M selama 120 menit, yaitu 68,75%. Yield Ce tertinggi diperoleh pada pelindian dengan rasio S/L 1:15 g/mL dengan konsentrasi 10 M selama 150 menit, yaitu 61,50%. Yield total 5 unsur LTJ tertinggi diperoleh pada pelindian dengan rasio S/L 1:15 g/mL dengan konsentrasi 10 M selama 150 menit, yaitu sebesar 84,06%.

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This research aims to obtain rare earth metals from tin slag based on the most optimum sulfuric acid concentration and solid-liquid ratio in the acid leaching process. This research varied the sulfuric acid concentration of 4, 6, 8, and 10 M, as well as the solid-liquid ratio (S/L) of 1:10 and 1:15 g/mL. The initial treatment of the tin slag sample was sifted to obtain a uniform size of ≤ 100 mesh, then heated in a furnace at a temperature of 700°C, followed by acid leaching using sulfuric acid. Acid leaching was carried out with the help of a magnetic stirrer at a temperature of 40°C for 30-180 minutes and the yield of extracts of the elements cerium (Ce), niobium (Nb), and total rare earth metal elements in the form of cerium (Ce), lanthanum (La), neodymium were determined. (Nd), praseodymium (Pr), and yttrium (Y). The leached extract was characterized using the ICP-OES (inductively coupled plasma - optical emission spectrometry) test to obtain the rare earth metal content at each variation in time, acid concentration and solid-liquid ratio. The highest Nb yield was obtained in leaching with an S/L ratio of 1:10 g/mL with a concentration of 8M for 120 minutes, namely 68.75%. The highest Ce yield was obtained in leaching with an S/L ratio of 1:15 g/mL with a concentration of 10 M for 150 minutes, namely 61.50%. The highest total yield of 5 REE elements was obtained in leaching with an S/L ratio of 1:15 g/mL with a concentration of 10 M for 150 minutes, namely 84.06%.