Mineral Processing
Mostafa Maleki Moghaddam; Hosein Najmaddaini; Saeid Zare; Masoud Rezaei; Mohammad Ali Motamedineya; Gholamreza Biniaz
Abstract
Abstract
The structural characteristics of mill liners, such as lifter shape and mill speed, significantly influence the grinding process. At the Sarcheshmeh slag flotation plant, the 6×6 meters SAG mill was initially equipped with 48 rows of liners, designed in a Hi-Lo configuration for the first ...
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Abstract
The structural characteristics of mill liners, such as lifter shape and mill speed, significantly influence the grinding process. At the Sarcheshmeh slag flotation plant, the 6×6 meters SAG mill was initially equipped with 48 rows of liners, designed in a Hi-Lo configuration for the first half and a Lo-Lo configuration for the second. Throughout the mill shell liner's 1700-hour operational period, monitoring identified 30 failures. Investigations revealed that defects in the liner design and improper charge motion were the main causes. This study proposes modifications and standardization of the shell liner design, tailored to the specific circuit conditions, to enhance performance and reliability. The redesign included several key changes: 1) Reducing the number of rows: The number of liner rows was decreased from 48 to 32. 2) Adjusting lifter angle: The lifter angle was increased from 23 to 30o to optimize performance. 3) Eliminating Hi-Lo design liners: The Hi-Lo design liners were changed to Hi-Hi, and 4) Reducing liner variety: The variety of liners was streamlined from 5 types to 2. The installation of the proposed liners optimized the charge trajectory for grinding, resulting in higher liner's lifetime. It extended the liner life by 30% and eliminated liner failures, reducing them from 30 to zero. The wear rate for the proposed design was 0.05 mm/hour, while the original design had a wear rate of 0.11 mm/hour. This difference corresponds to a factor of 2.3 times improvement.
Mineral Processing
M. Maleki Moghaddam; E. Arghavani; A.R. Ghasemi; S. Banisi
Abstract
Liner design has become an increasingly more important tool for the AG/SAG mill performance optimization. The Sarcheshmeh copper complex concentration plant uses a SAG mill lined with 48 rows of Hi-Low type liners. Because of breakage of Low type liners and cold welding, the liner replacement task of ...
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Liner design has become an increasingly more important tool for the AG/SAG mill performance optimization. The Sarcheshmeh copper complex concentration plant uses a SAG mill lined with 48 rows of Hi-Low type liners. Because of breakage of Low type liners and cold welding, the liner replacement task of Low with new Hi type liners has become very difficult and time-consuming. With the objective of finding a new design for liners, numerical (3D DEM; discrete element method) simulation and physical modelling in a laboratory mill were used. It was found that changing the liner type from Hi-Low to Hi-Hi could provide an appropriate charge trajectory. The new Hi-Hi type shell liners were designed, manufactured, and installed. With the new liners, the number of broken liners over liner life reduced from 6 to 0 piece, the total changing time for one liner decreased from 21 to 16 minutes, and no cold welding of shell liners was observed. Comparison of the feed rate before and after installation of the new liners for a period of liner life showed an increase from 750 to 850 t/h, which was indicative of a higher flexibility of the mill in encountering ore hardness variations.
M. Jahani; M. Noaparast; A. Farzanegan; G. Langarizadeh
Abstract
In this research, the efficiency of the comminution circuit as well as the efficiency of size classification equipment of the concentrator plant 2 of Sarcheshmeh copper complex was studied. The comminution circuit of this plant includes one SAG mill in a closed circuit with a vibrating screen and one ...
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In this research, the efficiency of the comminution circuit as well as the efficiency of size classification equipment of the concentrator plant 2 of Sarcheshmeh copper complex was studied. The comminution circuit of this plant includes one SAG mill in a closed circuit with a vibrating screen and one ball mill with a size classification system of hydrocyclone. The goal of this work was to calculate the proportion of each of these mills at energy consumption and generating suitable product for flotation as a further process. Three stages of sampling were performed and consumed energy was also modeled. The average efficiency of the initial ball mill was obtained which was equal to 72.96%. The average of the proportion of (consumed) energy by SAG and ball mills from total consumed energy at mills, was 44.65% and 55.35% respectively. The proportion of SAG and ball mills in producing the final product (particles finer than 74 µm) was 55.38% and 44.62% respectively. That is, the SAG mill produces about 10.76% more than the ball mill in the final product. The average consumed energy at SAG and ball mills to produce one ton of final product was 23.16 kWh/t and 36.05 kWh/t respectively. Thus, the ball mill consumes 12.89 kWh/t, more energy than the SAG mill in producing the final product. The average cyclones’ imperfection was 0.361 and therefore the average efficiency of cyclones’ separation was equal to 63.9% and the average efficiency of the vibrating screen was equal to 99.89%. As overflow of the initial cyclones (final product of comminution circuit) forms feed of rougher cells, cyclones’ inappropriate performance could severely influence the whole flotation process.
