ANALYSIS OF THE EFFECT OF GRINDING BALL SIZE BLENDING ON THE OPTIMATION OF MILL CIRCUIT AT PT. ANTAM UBPE PONGKOR PROCESS PLANT

• Main Author: APRIYANTO (NIM : 12509034), ANDI
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/21038
• Institution: Institut Teknologi Bandung

PT. Antam UBPE Pongkor is one of underground gold mining in Indonesia. For the last five years, from 2008 until 2012, feed grade of PT. Antam UBPE Pongkor decreases, and drastically decreases in 2011 and 2012. In 2008, feed grade of PT. Antam UBPE Pongkor is 9,20 gpt. While in 2012, the feed grade decreases to 6,14 gpt. Gold recovery following feed grade also decreases from 93.2% in 2008 to 90.7% in 2012. Furthermore, with almost the same throughput and lower feed grade, the gold production goes down. There are several solutions that PT. Antam UBPE Pongkor do to overcome these problems, and optimation on the mill circuit is one of them. <br /> <br /> <br /> <br /> In this research, optimation is done by blending grinding ball which has already exist in the ball mill of PT. Antam UBPE Pongkor plant 1 that has a size of 80 mm, with new grinding ball that has a size of 60 mm. By this blending, we expect that there is an increase of fine particle fraction quantity on ball mill discharge. Samples are taken at several point, such as ball mill discharge, cyclone feed, cyclone overflow and underflow 1 and 2, and autosampler overflow. Sample processing is done by wet sieving method at several size of sieve, namely: 297, 149, 106, 74 and 44 &#956;m for ball mill discharge; 74 and 44 &#956;m for cyclone overflow; 74 and 44 &#956;m for cyclone underflow, and 44 &#956;m for autosampler overflow. After that, fire assay analysis is done to find out the assay of precious metal and metal distribution of these sample. <br /> <br /> <br /> <br /> The results at the experiments show that there are an increase of fine particle fraction quantity in the amount of 1,49% on discharge ball mill after blending the size of grinding ball is done. This increase causes a decrease on circulating load in the amount of 7%. We can also observe that a decrease of percent solid of cyclone feed in the amount of 3,24% causing a decrease of percent solid of hydrocyclone products in the amount of 3,73%, 4,66%, 3,04%, and 1,34%, respectively on cyclone overflow 1, cyclone overflow 2, autosampler overflow, and cyclone underflow 2. These decreases cause an increase of weight percentage of ore that pass on 74 &#956;m sieve size, namely in the amount of 9,33% and 15,75% on cyclone overflow 1 and 2, and 7,81% on autosampler overflow. We also observe that there are an increase of gold metal distribution after blending the size of grinding ball in the amount of 5%, 15%, and 11%, respectively on ball mill discharge, cyclone overflow 1, and cyclone overflow 2.