Engineering & Mining Journal

SEP 2017

Engineering and Mining Journal - Whether the market is copper, gold, nickel, iron ore, lead/zinc, PGM, diamonds or other commodities, E&MJ takes the lead in projecting trends, following development and reporting on the most efficient operating pr

Issue link: https://emj.epubxp.com/i/872627

Contents of this Issue

Navigation

Page 90 of 99

SEPTEMBER 2017 • E&MJ; 89 www.e-mj.com PROCESSING SOLUTIONS of the liner change one should consider changing the liners. At a glance, the lin- ers may still have what is perceived as us- able wear left, but at a lost tonnage that doesn't benefi t the plant. Detecting Wear Part Damage If one observes signifi cant wear-part dam- age during regular inspections, consult the crusher manufacturer to fi nd out if immediate stoppage is warranted. Determining whether to stop produc- tion to change a wear part entirely de- pends upon the severity of the damage. For example, a damaged rotor tip in a VSI crusher may make it through the shift and not cause unwanted downtime. However, a broken jaw die with parent steel ex- posed may cause signifi cant damage, and it is vital the operator stops the jaw crush- er and change the die in order to protect the crusher frame. Avoiding Common Mistakes Failing to take care of damaged wear parts can increase wear on the entire machine which can lead to expensive failures. A common misconception is that oper- ators think they should use jaw dies until they are completely worn fl at or develop a hole or crack. By running these wear parts for a longer period of time, oper- ators think they are extending the wear life, but in reality they may be causing unnecessary stress to the jaw frame. Another common mistake that has been witnessed is that operators run cone crusher liners past their useful operation- al life. The cost of lost tonnage can great- ly exceed the amount that a liner change would cost. Safety is No. 1 Most manufacturers now design cone crushers with advanced hydraulic sys- tems to raise, lower and adjust the ma- chines safely with minimal effort. To clear a cone crusher, users simply press a but- ton, click the mouse or toggle a switch. This removes the risk of people manually clearing a stalled cone crusher by hand or using straps, chains and rolling stock to adjust their crusher. Jones said safety is Weir's top pri- ority and its latest designs refl ect this. For example, the Trio TP cone crusher range has self-protecting features to help achieve high levels of mechanical reli- ability under severe operating conditions while ensuring the safety of both the op- erator and equipment. In addition, the latest Trio CTHT se- ries jaw crusher includes a hydraulic tog- gle relief system. This innovative, built- in system protects the jaw crusher from overloads caused by uncrushable materi- al. The hydraulic toggle is designed to be a reliable and safe relief system, without unnecessary complexity for the operator. Without proper crusher maintenance, an operation may experience poor perfor- mance and decreased service life of the machine. Weir suggests that operators seek expertise to create and execute a maintenance plan to increase the service life of their crusher. Water Treatment Optimization through Innovation The importance of water conservation and management in mineral processing can be expressed in a few short sentences that resemble circular logic: Water is an inte- gral part of mining. Ore processing is water intensive and results in the production of tailings. The recovery of water from tailings is essential to mining operations, especially in arid climates with scarce water sources. Chris Biederman, senior engineer and technology development lead in the Water & Natural Environment Business Unit at engineering fi rm Hatch, recently described in an online blog post (www.hatch.com/en/ About-Us/Publications/Blogs/2017/05) how Hatch has learned to use bench-scale testing to assist in quick and effi cient formulation of optimum strategies for re- covering and, if necessary, treating water from typical mine-site sources such as a Tailings Management Facility (TMF). Biederman acknowledged that direct recycling of water from a TMF without treatment is preferred, given the large vol- umes of water in circulation. If treatment is required, steps should be taken to de- crease water usage as much as possible and to optimize water treatment systems to manage operating costs. Bench-scale testing is one tool available to achieve this objective. He described smart ap- plication of bench-scale testing as "a cost-effective way to evaluate various technologies in support of new capital projects, or troubleshoot and optimize an existing treatment system," but warned that bench-scale investigations should not replace long-term pilot programs at scale; instead bench-scale tests should be viewed as complementary and used to inform the piloting phase. He offered three principal guidelines: Test at the source. When dealing with complex mine waters, variations in water quality often occur. These variations may be seasonal — for example an increase in turbidity due to run-off — or can be pro- cess-related and result in signifi cant chang- es to water quality over a short timeframe. Testing should be conducted in the fi eld to get the most applicable results. By testing in the fi eld, changes to water chemistry as a result of shipping samples offsite and sample storage conditions are eliminated. This is particularly important for waters that may be saturated in dissolved salts, where fl uctuations in temperature can cause pre- cipitation to occur prior to testing. Challenge the status quo. Typically the standard "jar test" method is the go-to for coagulation and fl occulation tests. Jar tests are best used to evaluate the perfor- mance of a small number of chemicals when precedent exists for treating a par- ticular water stream. Each individual jar test requires 1 liter of sample, so there are practical limitations to the number of tests that can be performed in a reasonable amount of time for a given water sample. The volume of raw sample required to run numerous jar tests also limits the number of tests that can be reasonably performed. However, Hatch has successfully devel- oped and applied high-throughput meth- ods to test mining waters and tailings. The methodology involves simultaneous testing of up to 48 treatment conditions using small sample volumes (15 mL or 50 mL). The result is a very effi cient method to screen multiple chemicals, oxidants, or pH conditions all while minimizing the amount of raw water sample required and maximizing the number of tests and data collected. This method has proven to be very effective when testing mine waters having complex water chemistry. Respond Rapidly. Portable battery-oper- ated instruments for water testing allow for in-fi eld measurements and timely feedback to guide bench-scale tests. Further, water analytics are benefi ting from miniaturiza- tion as chip-based sensors are becoming smaller and thus more portable. Innovative solutions are also available for measuring very low concentrations of select contami- nants using biological-based sensors. All of this supports the ability to quickly mobilize

Articles in this issue

Links on this page

Archives of this issue

view archives of Engineering & Mining Journal - SEP 2017