CASSITERITE FLOTATION OF SKARN TYPE PRIMARY TINORE FROM BELITUNG ISLAND

• Main Author: Kamoda, Rustam
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/68002
• Institution: Institut Teknologi Bandung

Indonesia as one of the world's tin producers, not only has tin reserve from secondary deposits, but also has tin reserve from skarn-type primary deposit located on Belitung Island. Cassiterite is a common mineral found in skarn-type primary tin deposits. The characteristics of cassiterite in primary tin deposits are generally fine, disseminated, and brittle. These characteristics can cause finer size of cassiterite and the formation of slime from impurity minerals with a relatively shorter residence time than cassiterite when they are ground. Nowday, the separation of cassiterite by gravity method is limited by grain size of ?20 ????m, so that finer size of cassiterite tends to be disposed with tailing. Flotation process can be applied to separate fine cassiterite from impurities in skarn-type primary tin ore. There are several factors that can affect the separation of valuable mineral by flotation method namely mineral association, chemical reagent used, pH condition, presence of slime, grain size, etc. The sample used in the flotation experiments was skarn-type primary tin ore from Belitung Island which has been prepared and it was the P100 140# product of jar mill. Generally, the flotation experiments carried out in three schemes. The first scheme was flotation on samples without desliming treatment, the second scheme was flotation with desliming treatment using hydrocyclone, and the third scheme was flotation on variation of grain size fractions. Flotation experiments of the first scheme consisted of two sub-schemes, namely flotation with the absence of depressant and flotation with the presence of depressant. Flotation experiments with the presence of depressant were carried out at pH 6, 7, 8, and 9 using salicylhydroxamic acid (SHA), sodium oleate (SO), and a mixture of both (SHA+SO: ratio 1:1) as collectors (each collector’s dosage was 1,500 g/t) and mixed of sodium silicate (SS) and starch (ST) ((SS+ST; ratio: 1:1); dosage: 3,000 g/t) as depressant. Flotation experiments in the absence of depressant were carried out at pH 8 (based on the best result of first sub-scheme) with various type of collectors (SHA; SO; and SHA+SO) with 1,500 g/t dosage of each collector. Flotation experiments in the second scheme consisted of three sub-schemes (all of sub-schemes was carried out at pH 8) namely flotation with various type of collectors (dosage: 1,500 g/t) with the use of SS+ST depressant (dosage: 1,500 g/t; ratio: 1: 1), flotation with the variation of SS+ST depressant dosage (0; 1,500; and 3,000 g/t) using SHA as collector (dosage: 1,500 g/t), and the flotation with various type of depressants ((SS; ST; and SS+ST); dosage: 1,500 g/t ) using SHA as collector (dosage: 1,500 g/t). Flotation experiments in the third scheme were carried out on various of grain size fractions (-105+88 ?m, -88+63 ?m, -63+37 ?m, and -37 ?m) using SHA+SO collector (dosage 1,500 g/t), starch depressant (dosage 1,500 g/t). /t) at pH 8. Recovery, grade, percent mass pull, enrichment ratio, separation efficiency, and selectivity index are the parameters used to assess flotation performance. The results of sample characterization showed that primary tin ore of the skarn type from Belitung Island contain 0.1615% Sn in the form of cassiterite. Generally, the experimental results showed that the flotation of cassiterite at various pH tend to show better performance at pH 8. The flotation results of the three type of collectors showed that the recoveries of Sn from SHA collector < SO < SHA+SO. In term of grade in the concentrate, the Sn grades of SO < SHA + SO < SHA. Flotation experiments without desliming treatment from the three type of collectors in the absence and presence of depressant showed that flotation performance was better in the absence of depressant. Desliming treatment using a hydrocyclone on P100 140# samples could cause Sn loss with hydrocyclone’s overflow of ±27%, but was able to increase the Sn grade from head grade to 0.1738%. Flotation of hydrocyclone’s underflow with various type of collectors showed that SHA+SO collector provide better performance than SHA and SO collectors. The use of high dosage of SS+ST depressant in the underflow flotation using SHA as collector resulted in suppression of cassiterite. The results of flotation on various type of depressants showed that the use of ST depressant had no significant suppression effect on cassiterite, resulting in higher cassiterite recovery compared to SS and SS+ST depressants. However, the grade of SS > SS+ST > ST depressant . Cassiterite flotation in the variation of grain size fractions showed a better performance in the coarser fractions (-105+88; -88+65; and -65+37 ?m ) compared to the finest fraction (-37 ?m). The order of flotation performance from the highest to the lowest respectively was -105+88 ?m > -88+65 ?m > -65+37 ?m > -37 ?m.