Selection of suitable linings for semi-autogenous grinding (SAG) mills guarantees the following benefits: considerable reduction in mill downtime; increased uptime and processing (improved plant availability); increased cost savings; and reduced maintenance costs.
The use of reliable lining is the tried and tested approach to increasing the availability of semi-autogenous grinding (SAG) mills. For this reason, informed decisions have to be made in the selection of lining material. The importance of suitable lining material is better comprehended when the role of the SAG mill is considered in the entire milling circuit.
Why availability of SAG mills
SAG mills are a vital cog in the grinding process. Usually, with a larger diameter than length, SAG mills are deployed specifically in a secondary process to reduce large feed size ore (where an industry-standard falls within the range ~300mm down to ~3mm). In contrast, ball mills, which are smaller in diameter than length, are used in primary, secondary or tertiary grinding applications to reduce material from ~20mm to very fine product sizes measured in microns.
So, given their specialised role, SAG mills must be available at all times. Any downtime can result in a loss of productivity, which translates into an irretrievable loss of revenue. But, inevitably, due to the materials they handle, SAGs are subjected to severe abrasion and impact, which results in wear and tear of the mill shell.
Conveniently, wear lining systems are the first line of defence of the mill shell, offering protection against abrasion and impact. During a product launch in 2021, FLSmidth regional product line and key account management director, Terence Osborn, highlighted the importance of liners reliable liners.“Grinding accounts for about 30% of the operational cost of a concentrator plant. Energy, liners and grinding media are some of several elements that constitute this substantial cost. Furthermore, the milling circuit consumes about 50% of a concentrator’s power demand,“ he said. In the other words, poor selection of liners is bound to fail, exposing the mill shell to wear and tear causing downtime.
Evidently, one of the opportunities to improve the efficiency of milling and grinding is available in the form of reliable lining. There is a need for products that offer a host of tangible benefits. Consequently, the process of selecting lining material has to be thorough.
Key selection considerations
When selecting a mill lining system, several key considerations must be taken into account, mainly:
- The mill liner must be constructed from high wear-resistant materials. As materials technology and design technology have advanced, today many superior alternatives exist to metal linings that have widened options;
- Specific information on the needed grinding action, mill size, ore and grinding media characteristics etc;
- Specific material should have the following characteristics: high hardness, elongation, tensile and tear strength; and
- Faster, easy and safe installation.
Host of benefits
Ultimately, there are a host of guaranteed benefits from the selection of suitable linings, specifically:
- A considerable reduction in mill downtime;
- Increased uptime and processing (improved plant availability);
- Increased cost savings;
- Reduced maintenance costs
Side Bar
Tega’s Mill liners
Tega Industries Limited is a name synonymous with pioneering achievement in the mineral beneficiation, mining and bulk solids handling industries the world over. Tega currently has six Manufacturing Units in the World and supplies products to more than 90 Countries. It is a dominant player in the World Market of Mill Liners.
In Africa, the mother company’s subsidiary, Tega Industries Africa Pty, Ltd, which is based in Brakpan, is under Mr Vishal Gautam who is Tega’s Business Unit Head. Gautam is responsible for Tega’s business Growth in the Continent.
On the emphasis of Tega Industries Africa’s offering, Gautam explains: “At Tega, we are selling solutions instead of products. We have resolved some very complex engineering problems related to Mills and Mill Liners and that has given us a lot confidence.”
Tega has been manufacturing Mill Liners for more than 40 Years. Today, Tega has a reference base of more than 600 Mills in the world and in Southern Africa alone we have more than 100 Mills Lined with Tega Mill Liners DynaMax™ Product range. Indisputably, there are very few companies in the world who can lay claim to that.
He mentions that when it comes to Mill Liners, the technology has changed very rapidly with respect to Design, Manufacturing and Condition monitoring. Tega is at the forefront of this technological shift: it has been extremely successful in developing, designing, manufacturing, and Installing the Mill liners in big diameter SAG Mills & Ball Mills. This is an incredible achievement since most of these Mills are very aggressive and hard applications.
Tega DynaPrime™
Tega’s mark of excellence in wear lining engineering is the Tega DynaPrime™. Tega DynaPrime™ has been engineered to reduce the number of pieces being installed inside the mill, substantially reducing the installation downtime for maximum mill operation uptime.
Tega Dynaprime™ Liners are now installed in a twelve-metre Diameter Mill which would probably be one of the biggest SAG mills in the world. Gautam underlines that the most notable aspect of the project is safety. “Tega DynaPrime puts safety above all and has taken measures to render the reline site safe. The option of Bolting from outside and lesser weight of the lining considerably reduces any risk during the installation of the liner.”
Partnerships in Practice
Vishal Gautam says the development of mill liners comes from a deep-rooted philosophy of Tega which is “Partnerships in Practice”. “Tega develops partnerships with customers daily with their Quality Product, Service and Turnaround time.”
Gautam believes this is a very interesting time for Tega, and regards the growth the company has experienced in the past few years as “something like a dream”. “We look forward to further growth. We are very aggressive in the market. We are looking at a very interesting trend in the market with respect to commodity prices since it’s opening new doors for us.” He concludes: “We walk the Talk. Please watch this space.”
