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The impact is discussed of liner design on mill operation, with reference to operating mill experience. Aspects discussed include shell liner design, mill charge levels, wide-space and large-angle shell lifters, the implications of ore characteristics for shell lifter design, end liner and grate structures, pulp lifters, pulp lifter charge motion, grate/pulp lifter interaction, pulp lifting capacity, curved pulp lifters, discharge cone wear patterns and design, bolting and liner size and materials. Advanced computing tools such as discrete element modelling, now incorporating slurry effects using smoothed particle hydrodynamics contribute to mill liner design by providing detailed illustrations and data on the interaction between liners and mill charge motion., The impact is discussed of liner design on mill operation, with reference to operating mill experience. Aspects discussed include shell liner design, mill charge levels, wide-space and large-angle shell lifters, the implications of ore characteristics for shell lifter design, end liner and grate structures, pulp lifters, pulp lifter charge motion, grate/pulp lifter interaction, pulp lifting capacity, curved pulp lifters, discharge cone wear patterns and design, bolting and liner size and materials. Advanced computing tools such as discrete element modelling, now incorporating slurry effects using smoothed particle hydrodynamics contribute to mill liner design by providing detailed illustrations and data on the interaction between liners and mill charge motion.

A process is described for the pre-treatment of Au-Sb concentrates to remove the Sb and to produce an Au-bearing residue suitable for cyanidation. The initial step involves the reaction of a sulphide concentrate with azeotropic hydrochloric acid. The products are an un- reacted Au-bearing residue, H2S, and a solution of SbCl3. In a commercial operation it is proposed that the H2S is absorbed in caustic soda to form NaSH in solution, which is a product used widely for sulphidisation. In the next step, the SbCl3 solution is hydrolysed with distilled water under controlled conditions to form the solid oxychloride Sb4O5Cl2. In a commercial operation the hydrochloric acid produced by the hydrolysis would be concentrated by evaporation to form an azeotropic strength hydrochloric acid and recycled to the leaching stage. In the final Sb processing step Sb2O3 is formed from the oxychloride by neutralisation with caustic soda (NaOH). Simple neutralisation produces valentinite, the rhombic form of antimony trioxide, but seeding the initial oxychloride mix with fine cubic senarmontite resulted in 100% senarmontite formation., A process is described for the pre-treatment of Au-Sb concentrates to remove the Sb and to produce an Au-bearing residue suitable for cyanidation. The initial step involves the reaction of a sulphide concentrate with azeotropic hydrochloric acid. The products are an un- reacted Au-bearing residue, H2S, and a solution of SbCl3. In a commercial operation it is proposed that the H2S is absorbed in caustic soda to form NaSH in solution, which is a product used widely for sulphidisation. In the next step, the SbCl3 solution is hydrolysed with distilled water under controlled conditions to form the solid oxychloride Sb4O5Cl2. In a commercial operation the hydrochloric acid produced by the hydrolysis would be concentrated by evaporation to form an azeotropic strength hydrochloric acid and recycled to the leaching stage. In the final Sb processing step Sb2O3 is formed from the oxychloride by neutralisation with caustic soda (NaOH). Simple neutralisation produces valentinite, the rhombic form of antimony trioxide, but seeding the initial oxychloride mix with fine cubic senarmontite resulted in 100% senarmontite formation.

An overview is presented of current practical approaches to semiautogenous grinding mill liner designs as they affect long-term liner performance, mill performance, and the interaction between grinding media and mill charge. Liners discussed include shell liners, with lifters that dictate charge motion, and mill-end liners, especially discharge-end liners that function to empty the mill of ground product. Experimental work and discrete-element modelling have shown that wider spacing of lifters and larger face angles should significantly improve performance, but experience has shown that they can result in charge slippage, liner wear and degraded overall performance. Tools for computing trajectories and charge levels can be used to investigate the operating system and interpret DEM results by comparing ball trajectories from new and worn lifters or low and high charge levels, their outputs being superimposed on DEM outputs. Both ball trajectories and low charge levels also affect end-liner design through the nature of ball impacts on end liners and grates. Straight-radial or curved pulp lifters control the contents within the mill as well as their discharge, curved lifters discharging rocks much sooner and more completely but requiring a commitment to unidirectional rotation of the mill., An overview is presented of current practical approaches to semiautogenous grinding mill liner designs as they affect long-term liner performance, mill performance, and the interaction between grinding media and mill charge. Liners discussed include shell liners, with lifters that dictate charge motion, and mill-end liners, especially discharge-end liners that function to empty the mill of ground product. Experimental work and discrete-element modelling have shown that wider spacing of lifters and larger face angles should significantly improve performance, but experience has shown that they can result in charge slippage, liner wear and degraded overall performance. Tools for computing trajectories and charge levels can be used to investigate the operating system and interpret DEM results by comparing ball trajectories from new and worn lifters or low and high charge levels, their outputs being superimposed on DEM outputs. Both ball trajectories and low charge levels also affect end-liner design through the nature of ball impacts on end liners and grates. Straight-radial or curved pulp lifters control the contents within the mill as well as their discharge, curved lifters discharging rocks much sooner and more completely but requiring a commitment to unidirectional rotation of the mill.

Efficient performance of pulp lifters is critical to the efficient performance of SAG and AG mills. Developments in the design of pulp lifters and associated grates of both conventional straight-radial and of curved type, and of the inner discharge cone are introduced. Issues covered include the discharge performance of both slurry and rock components, reverse flow back into the mill through open grates, and backflow down the pulp lifters of material that fails to discharge from the mill. Design experience is interpreted in the light of developments in particle flow modelling of the flow of charge in pulp lifters., Efficient performance of pulp lifters is critical to the efficient performance of SAG and AG mills. Developments in the design of pulp lifters and associated grates of both conventional straight-radial and of curved type, and of the inner discharge cone are introduced. Issues covered include the discharge performance of both slurry and rock components, reverse flow back into the mill through open grates, and backflow down the pulp lifters of material that fails to discharge from the mill. Design experience is interpreted in the light of developments in particle flow modelling of the flow of charge in pulp lifters.

It is important to recognise the impact of both back-flow and reverse-flow and the interaction between grate and pulp lifter design requirements on the efficient and effective performance of grates and pulp lifters. Pulp and solids flow in pulp lifter channels and mill charge structure as it relates to discharge through grates have been analysed in this practical approach to grate and pulp lifter design, which aims to maximise mill discharge effectiveness., It is important to recognise the impact of both back-flow and reverse-flow and the interaction between grate and pulp lifter design requirements on the efficient and effective performance of grates and pulp lifters. Pulp and solids flow in pulp lifter channels and mill charge structure as it relates to discharge through grates have been analysed in this practical approach to grate and pulp lifter design, which aims to maximise mill discharge effectiveness.

With the growth in size of semiautogenous grinding mills and the use of larger ball loadings and ball sizes, developments in mill linings have improved their wear and impact performance as well as mill grind and throughput. Shell liner developments include special mechanical design features such as special bolting, directed metal flow to prolong liner life, and a focus on the process aspects of the mills to provide more effective grinding motion with reduced wasteful ball-on-liner impacts. Grate design improvements aim to provide high throughput of material, especially in the larger size fractions, while providing good impact and wear life. Curved pulp lifters are designed to ensure complete discharge of coarse solids from the mill at high mill speeds., With the growth in size of semiautogenous grinding mills and the use of larger ball loadings and ball sizes, developments in mill linings have improved their wear and impact performance as well as mill grind and throughput. Shell liner developments include special mechanical design features such as special bolting, directed metal flow to prolong liner life, and a focus on the process aspects of the mills to provide more effective grinding motion with reduced wasteful ball-on-liner impacts. Grate design improvements aim to provide high throughput of material, especially in the larger size fractions, while providing good impact and wear life. Curved pulp lifters are designed to ensure complete discharge of coarse solids from the mill at high mill speeds.

Vortex pulp lifters and grates are now in operation both as original equipment and retrofitted to existing SAG mills. The development of the leading curve pulp lifter was based on an analysis of traditional radial pulp lifter operation. The lifters improve the discharge performance of SAG mills and feedback from field operations is showing both reduced grate wear and improved grate throughput. The spherical head-bolt and protection insert is a fastening system for heavy-duty liners in high-aspect-ratio mills. It has been designed for SAG mills where current operating practice and conditions place bolts under severe stress. The use of a spherical head and corresponding spherical bolt hole in the liner distributes the load more evenly in the contact zone between the bolt and the casting, reducing stress in this area by 30%., Vortex pulp lifters and grates are now in operation both as original equipment and retrofitted to existing SAG mills. The development of the leading curve pulp lifter was based on an analysis of traditional radial pulp lifter operation. The lifters improve the discharge performance of SAG mills and feedback from field operations is showing both reduced grate wear and improved grate throughput. The spherical head-bolt and protection insert is a fastening system for heavy-duty liners in high-aspect-ratio mills. It has been designed for SAG mills where current operating practice and conditions place bolts under severe stress. The use of a spherical head and corresponding spherical bolt hole in the liner distributes the load more evenly in the contact zone between the bolt and the casting, reducing stress in this area by 30%.