A sag mill is usually a primary or first stage grinder. Schematic diagram of agsag mill process mechanisms after. Achieving sag mill design production at startup using best. In sag mill operation, the grinding rate passes through a minimum at a critical size chapter 5, which represents material too large to be broken by the steel grinding media, but has a low selfbreakage rate. Efficient operation even at higher mill speeds operatorfriendly smooth mill operation significantly improve wear life can be precisely designed to handle the given capacity can be easily retrofitted to existing mills.
Sag mill optimisation and increasing throughput at. The igb was tested in the sag mill at cortez gold mines operations. Semiautogenous grinding sag mill liner design and development. Posted by matrix on 21st march 2007 sanjeev latchireddi, chief process engineer grinding americas, outokumpu technology, looks at the shift from ball mills to sag mills. In other words, a sag mill would exhibit a specific force histogram under a set of operating conditions. Actual comminution circuits consist in most of the cases in coarse crushing, sag milling, pebble crushing and secondary ball milling. In a continuously operating ball mill, feed material fed through the central hole one of the caps into the drum and moves therealong, being exposed by grinding media. Metallurgical contentball mill maintenance manualon mill installation and maintenanceball mill concrete foundationsgrinding mill foundationgroutingball mill sole plate am sure your ball mill is considered the finest possible grinding mill available. Typically operated in rsa on witwatersrand gold ore driefontein underground, kloof, jacobina 6 sag mill with recycle crusher 8 15% ball charge competent ores, better suited to coarse grind sizes. The design of a ball mill can vary significantly depending on the size, the equipment used to load the starting material feeders, and the system for. The material grinding occurs during impact falling grinding balls and abrasion the particles between the balls. Jun 19, 2015 a ball charge level has a significant effect on overall charge motion. If the sag mill is not intended to be the ratelimiting step in a process plant, then it is best to adjust the sag load and power to hold a constant tonnage to satisfy another constraint elsewhere.
The results have seen a decrease in process variance with an associated increase in average circuit performance. It then correlates this data to give an accurate picture of conditions inside the mill. How does a sag mill work crusher mills, cone crusher. So yes, there are situations where constant tonnage is appropriate.
Rajamani4, professor metallurgical engineering 1barrick cortez gold mines star hc66 box 1250. Optimizing performance of sabc comminution circuit of the wushan porphyry copper minea practical approach. The laboratory benchscale sag mill reproduces operating conditions of a commercial sag mill. Comminution simulation using discrete element method dem approach from single particle breakage to fullscale sag mill operation lawrence k.
The total volume inside the mill is given by vm 4 d2 ml 1 2lc l l 1 dtdm 3 1 dtdm 8. Because of segregation on the coarse feed stockpile, sagmill 2 receives a higher percentage of coarse material. The results in sagmill line 2 are even more dramatic. The knowledgescape strategys ability to maintain smooth and stable operation of the mill was more apparent when contrasted to the dcs control on the difficult line. Sag mill 4% ball charge, 90% nc a cross between ag and sag for average competency, abrasive ores. This paper details the operation of the ultra fine grinding. Chandramohan, r, braun, r, lane, g, hollis, k, le, j and baas, d, 2018. Our experts welcome the opportunity to assist you with circuit and circuit control design as well as startup, operation, and optimization of your mill. In these circuits the sag mill is the largest energy consumer. This video was made for the sag conference, in which a company wanted to show a visual walkthrough of the sag mill, from the beginning of its processes to. Understanding size effects of semiautogenous grinding sag mill operation as a pathway to solving feed disturbances case study using the mmg century sag mill, in proceedings th ausimm mill operators conference 2016, pp 3230 the australasian institute of mining and metallurgy. The operating principle of the ball mill primo pizza. Our union speaking on the silver carpet at the 26th annual screen actors guild awards 2020. Quantitative estimations of these parameters can be found in 4, 5, 23.
The plain vertical machines are characterized by a spindle located vertically, parallel to the column face, and mounted in. The ability to mill a broad range of ore types in various circuit configurations, with reduced numbers of unit operations and a. The tendency of the charge to slip back along the rising side of the shell is reduced as charge level increases, until. The grinding circuit optimization application is the first technology to accurately predict critical sag mill performance variables. A minetomill study was conducted to improve the grinding circuit operation. Pdf the jkmrc has been studying and modelling industrial ag and sag mills. This commutation is an essential part of many processes. Optimizing your sag mill operation international mining. The speed of rotation of the mill determines three basic types of operation modes. As such you will find it is designed and constructed according to heavy duty specifications. The geometry of a mill with conical ends is shown in figure 8. Yet the sag mill of newmonts yanacocha mine in peru is a.
While there is no generic control strategy for sag. The grinding mill will be installed during 2014 at first quantums kansanshi copper mine. Companies are using this technology to determine the size of particles being processed in the sag mill. Introduction there are four main aspects of sag mill design that will be discussed in available in the sag mill and ball mill. They are available for arbor mounting, or with an integral shank with or without a pilot. Sag mill is an investment that can produce handsome returns if extra production is needed or simply to give the mine the option to mill the hardest ores at design throughput rates. Ag or sag mills have been in use in comminution circuits since the 1950s and. Evolution of liner design from current to future operations julius stieger1, process superintendent dave plummer2, process maintenance planner sanjeeva latchireddi3, chief process engineer raj k. This type of helical cutter is particularly useful for milling elongated slots and for light cuts on soft metal. Such comminution is an important unit operation in many processes. If the critical size material, typically 2550 mm, is accumulated the mill energy efficiency will deteriorate, and the mill feed. Pdf understanding the effects of liner wear on sag mill. When a part fails, you need to make the right decision to get your plant up and running. Pdf evolution of sag mill process control at the xstrata.
Early sag mills had a diameter of about 32, later increasing to 34, 36, 38 and 40. The optimal performance of agsag mills is the key to successful plant operation. The designs of autogenous and semiautogenous sag grindings mills are described followed by the description of their methods of operation in grinding circuits involving crushers and ball mills. Four sets of sag mill operational data are graphed as histograms in figure 10. Sag mill energy required according to this statement, is 2. Please feel free to give your inquiry in the form below. Understanding size effects of semiautogenous grinding sag. Every mining operation has a unique grinding process. The histogram shown here paves the way for sag mill signature. Pdf the new practice of applying full precrushing of sag mill feed to substantially increase. Having oversize material entering the sag mill makes an operation less efficient, costing companies money in electrical and maintenance costs.
The mill will be driven by a gearless motor drive gmd which, at 28. With the development of the kx3 cnc key to both is the use of precision ball just cant be done effectively on a manual mill. Overview on the grinding mills and their dual pinion mill drives abstract this paper will first give a short overview of the copper mountain project in british columbia, which just has started commercial operation earlier this year. A mill is a device that breaks solid materials into smaller pieces by grinding, crushing, or cutting. In this case, mill speed is the primary manipulated variable used to control mill load. Understanding the effects of liner wear on sag mill performance conference paper pdf available september 2015 with 1,495 reads how we measure reads. Grinding circuit design tools, including for sag millball mill circuits, and geometallurgy energy models are available to subscribers.
Metso has experience of over 8,000 grinding mills globally, including manufacturing and delivering the largest sag ag mills in the world. In the case of the large sag mill referred to in fig. Sag mills operation data abstract comminution, particularly milling, is on average the largest consumer of energy in mining. There are many different types of mills and many types of materials processed in them. Sag mills are autogenous mills that also use grinding balls like a ball mill. Sagaftra members united in solidarity for fair union contracts. Recent new plant sag mill startups in canada have shown that. An expert system applied to the control of mineral process unit operations is, by its nature, the site best.
One major issue was the operation of the sag mill caused vibration at an amplitude of up to 11 mm on the mill foundation and therefore it could not be operated at a production rate above 15,000 t. Because sag mills rely both on the ore itself as grinding media to varying. Join thousands of sagaftra members from across the country sharing their union pride. Today we will learn about difference between sag mill vs ball mill.
This paper describes the methodology by which the neural network model was implemented, the considerations. Your mill is at the heart of your production process. Metso provides grinding mill parts for equipment previously sold under a variety of trade names and has oem parts to fit seamlessly with your existing mill and process. The sag mill design is based on outotecs proprietary grinding mill technology, developed over decades for maximum reliability and performance. Photoanalysis is being used on sag mills worldwide to control the size of rock being crushed. Grinding mills for mining and minerals processing metso. Comminution simulation using discrete element method. In this training module, well cover the workings of a semiautogenous grinding mill, or sag mill, thats designed to be the first stage of a grinding circuit. Herbst svedala optimization services september, 2001 abstract. Terms used in sag mill design and operation to begin, it is necessary to understand the terms used when discussing sag mill testing, design and operation. Mineral processing design and operations sciencedirect. Even though the device worked well it could not withstand the impacts in the plant scale mill. Difference between sag mill vs ball mill mech4study.
The operations comminution circuit, which comprises a semiautogenous sag mill and two ball mills, each with megawatts mw of installed power, was expected to be sag mill limited when. Flsmidth, usa design sag mill production when you need it most. Operating specifications were selected to achieve an optimum of capital and operating costs. Reline machines 16 it is a well recognised fact that global ore grades are declining while commodity demands continue to rise. The sag mill model in the jksimmet software has not been shown to accurately reproduce the performance of a single stage mill for greenfield design. The sag mill is 26 diameter x 123 egl and powered by 4,500 hp motor driven by a variable speed lci drive that can control the mill speed from 36% to 80% of critical speed depending on ore type and operational demands. Ultra fine grinding a practical alternative to oxidative. Nowadays, the more successful plants are those that have adopted effective and. Optimizing performance of sabc comminution circuit of the. A ball mill is a type of, a rock tumbler functions on the same principle ball mills are also, it is suitable for both batch and continuous operation, get price.
Each type is characterized by a specific trajectory of motion of the charge in the mill and a different impact of the milling bodies on the ground material. The phu kham operation has recently undergone a series of process improvements to treat the anticipated competent ores scheduled for 2017 and 2018. A method of c alculating autogenous semiautogenous. Improving autogenoussemiautogenous grinding performance and. The extremely high throughput is facilitated by incorporating the use of outotecs patented turbo pulp lifter tpl technology. Frozen charge detection and automatic loosening with gearless. Methods of estimating sag mill volumes, mill charges, feed size and power consumptions and optimum speeds of rotation during operation are described. In the light of increasing interest in that technology various. This allows mines to reduce downtime in operations by reducing scheduled liner wear inspections and unnecessary changes.
As of 2010, in the world mining industry, about 200 large mills of full or partial sag were in operation, including about 100 of them working in the iron ore industry, 30 in copper, while others. Typically a sag mill has a much larger diameter compared to its length. Typical tests required to define a hardness variability function, are given below in figure 1. Gearless mill drives machinery risk solutions practice 2009 matt dugalic p. Backfill specialists acquisition 11 vpf technology 12 product news. Sagaftra members are the faces and voices that entertain and inform america and the world. Jan 08, 2016 in this training module, well cover the workings of a semiautogenous grinding mill, or sag mill, thats designed to be the first stage of a grinding circuit.
It is required for predicting throughput in an existing mill. The desired throughput of the mill is multiplied by the specific energy to give the mill power requirement. A control strategy recently implemented on a large variablespeed sag mill at mmgs century zinc operation in australia is shown in the chart found on pg. Grinding mills used in the mining industries are the most energyintensive. Comminution simulation using discrete element method dem. The telfer train 1 sag mill operational data was collected for a six week prior to the installation of the manta cube. Frozen charge detection and automatic loosening with. Ag and sag mills are now the primary unit operation for the majority of large grinding circuits, and form the basis for a variety of circuit configurations.
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