<\/p>\n
![\"Mining](\"https:\/\/www.schwingbioset.com\/wp-content\/uploads\/2023\/04\/Mine2V_cropped.jpg\")
Prior to the early 1980s, if poor soil conditions prevented a mining operation from safely accessing a rich vein of ore, that company had little recourse but to abandon the area in question and lose the ore contained within. It was generally accepted as a costly but unavoidable facet of the business. Today, however, techniques such as underhand cut and fill mining, in which cemented mill tailings are used to backfill the mined-out stope, allowing subsequent stopes to be cut beneath previously mined areas, have established themselves as a viable alternatives for working in such conditions. While not as frequently relied upon\u2014due in large part to the added costs associated with it\u2014underhand cut and fill has proven to be a valuable method and found its way into mainstream mining practices. As a result, many companies are pulling high quality ore from areas once viewed as unreachable. One of those, Montana\u2019s Stillwater Mining Company, has been successfully employing that approach for more than a decade now and, with the help of a KSP 80H(K)R pump from Schwing Bioset to deliver the paste for that process, has literally \u201cgone where no man has gone before.\u201d<\/p>\n
Big Sky Mining<\/strong><\/span><\/p>\n While only a few hundred tonnes are produced annually, platinum group ores are generally used for catalytic converters in cars, jewelry, and even dentistry equipment. According to Wayne Fallis, Stillwater\u2019s Stationary Equipment Maintenance Planner, the ore is mined, crushed fine, and then run through a flotation process. During the flotation process the metals are skimmed off and excess water is removed.<\/p>\n \u201cAt that point, it is concentrated to about 30 to 35% metals but there is still a good deal of dirt and rock contained within,\u201d he says. \u201cSo it is sent to a refinery where it is run through a flash furnace to remove the base metals, leaving a finished mineral product. The tailings from that initial extraction process are routed to the paste plant where, after processing, they will eventually become the mixture used in the backfilling process.\u201d<\/p>\n To make that paste happen, the mill tailings are first mixed with a flocculent to settle out the silt-sized fines (called slimes). Excess water is extracted and the residual material is pumped up and onto the belt of the vacuum filter to a depth of about \u00be-inch where even more water is removed.<\/p>\n \u201cThe filter is critical in that it not only further reduces water content, it also removes the slimes that were not taken in suspension,\u201d says Fallis. \u201cThis is important because slimes can have an adverse effect on the final product by reducing the paste\u2019s strength when the cement is setting up; that simply can\u2019t be allowed. By the time material gets to the end of the belt it is fairly dry: water contents are generally only about 18 – 20%. We then send it to a pug mill where the cement and any additives are mixed. When it drops out the other end it is finished product: paste ready to be pumped to a waiting stope.\u201d<\/p>\n Long Way to Go<\/strong><\/span><\/p>\n Where that stope will be depends, of course, on a host of factors. But, as mentioned, it will generally be in an area with poor soil conditions \u2014 areas prone to rockbursts, for example. Stillwater’s Mine Engineer, John Marjerison, says the decision to go with underhand cut and fill starts with the initial core sample.<\/p>\n “If we do the diamond drilling and geotech assessment and the core shows the ground to be very poor quality, we might decide that we have to take our licks on the first cut and really over-support that rock. In some instances we might even be shotcreting on the way in. Once we get that first cut done and backfilled with paste, however, we know what our back integrity is because we already know what that paste strength is.\u201d<\/p>\n At Stillwater, the distance to the stope being backfilled can be (and has been) greater than 7,000 feet. To move the paste that distance, the company installed a KSP 80 pump from Schwing Bioset (Somerset, WI) powered by twin 150 hp electric motors back in 1998.\u00a0Marjerison says that, despite the relatively limited role underhand mining plays in Stillwater\u2019s everyday operation\u2014it is used for roughly 10% of the stope backfilling\u2014the pump is the ideal tool for the job.<\/p>\n \u201cTo move a material with a high solids content that distance would be a challenge for any piece of equipment,\u201d he says. \u201cGranted, in many of the deeper stopes, the material has gravity helping it out. However, that\u2019s not always the case; we\u2019ve pumped some really long distances without much of a vertical drop at all. But the combination of the stoutness of the pump and our efforts to produce a nice consistent product out of the mixer has really paid off. When needed, we’ve been getting steady pour rates in the 90 ton-an-hour range and holding to that rate for 6-hour, 12-hour, even 18-hour continuous pours. We’ve been very pleased with that level of performance.”<\/p>\n Designed for Strength<\/strong><\/span><\/p>\n Stillwater Mine\u2019s pristine location also puts it literally at the end of the power grid, making outages a distinct possibility, particularly in the harsh Montana winters. To deal with a service interruption to the Schwing Bioset pump\u2014which could be catastrophic if it occurs in mid-pour\u2014the company maintains a diesel-powered oil field mud pump.<\/p>\n \u201cThat is our only backup for getting the pipes cleared if we have an outage,\u201d says Fallis. \u201cIf the paste hardens in the pipe it is a real nightmare. More importantly, however, if the pour is interrupted for any length of time, because of the risk of cold joints we can\u2019t simply resume pouring. We\u2019ve had instances where that\u2019s been the case and we\u2019ve had to drill and blast a partially-filled stope to start over. It\u2019s not what we like to do.\u201d<\/p>\n All About the Prep<\/strong><\/span><\/p>\n Prior to backfilling, Stillwater first lays down a bed of anywhere from 1 \u2013 1 \u00bd feet of broken rock or prep muck on the floor of the mined stope. Doing so not only offers something of a buffer from subsequent blasting which will take place below the newly-filled stope, but also acts as a base in which to drive DYWIDAG reinforcing bolts and plates for added strength. The addition of wire mesh on the floor and construction of a seven foot-high wooden retaining wall to hold the paste in place, complete the preparation, making the stope ready for backfilling.<\/p>\n \u201cThere\u2019s no denying that there is a lot more work and additional cost to doing underhand mining,\u201d says Fallis. \u201cIt might take ten days or so just to get a stope ready for the pour, then the paste has to cure for another seven days after the pour itself. That\u2019s two-plus weeks of lost production on that stope. However, we are now safely able to get to ore that we couldn\u2019t before\u2014and the key phrase there is \u2018safely.\u2019 Stillwater Mining places a tremendous amount of emphasis on doing things the right way and has an enviable safety record within the industry to show for it. Underhand mining might only be used 10% of the time here, but we\u2019re happy to be able to make that 10% happen.\u201d<\/p>\n Visite nuestro sitio web<\/span><\/strong><\/a>\u00a0to read more about our products and solutions, then\u00a0Cont\u00e1ctenos<\/strong><\/a><\/span>\u00a0para obtener m\u00e1s informaci\u00f3n sobre este proyecto o descubrir c\u00f3mo podemos ayudar tambi\u00e9n a su planta.<\/p>\n <\/p>\nDescargue nuestros folletos e informes de aplicaciones<\/a>\nSubscribe to Start Receiving Schwing Bioset eNews<\/a>\n [\/et_pb_text][\/et_pb_column][\/et_pb_row][\/et_pb_section]<\/p>","protected":false},"excerpt":{"rendered":" \u00a0As a recognized leader in the Mining Industry, Schwing Bioset, Inc. (SBI) provides Mining Pumps designed for paste, thickened tailings, slimes, and any other high solids slurries, pumping application. Delivering dependable service day after day in underground and surface operations,\u00a0 SBI pumps are known to stand up to the harshest of site conditions, proven by […]<\/p>","protected":false},"author":3,"featured_media":3561,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_et_pb_use_builder":"on","_et_pb_old_content":"![\"\"](\"https:\/\/www.schwingbioset.com\/wp-content\/uploads\/2023\/04\/Pugmill_cropped.jpg\")
Working a geological formation in southern Montana known as the J-M Reef, Stillwater Mining Company extracts, processes, smelts, refines, and markets palladium and platinum, as well as a limited amount of copper, silver, rhodium, and gold. Located at the foothills of the Beartooth Mountains in southern Montana, the area represents the only known considerable source of platinum group metals in the United States, and is one of the most significant sources outside Russia and South Africa.<\/p>\n![\"Mining](\"https:\/\/www.schwingbioset.com\/wp-content\/uploads\/2023\/04\/Stillwater-Hopper-Picture-scaled.jpg\")
The mix design at Stillwater to which Marjerison refers, includes a 10\u201312% cement content and a Euco-Fill 31 water reducing and plasticizing admixture that develops 586 kPa (85 psi) of unconfined compressive strength (UCS) after seven days. Though lower in strength than paste used at other comparable mines also doing paste backfilling (a result of the large amount of -44 micron [-325 mesh] particles in the mill tailings), the company benefits by being able to reduce velocity in the pipelines to about 0.64 m\/sec (2.1 ft\/sec), less than one-third that of the other mines.<\/p>\nSchwing Bioset, Inc. has been your source for complete biosolids treatment and handlings systems for over thirty years. Growing from a biosolids handling supplier, we now offer process systems as well, including nutrient management, screw press dewatering, piston pumps, screw conveyors, Class A alkaline stabilization and drying technologies, sliding frames, live bottoms, conveyors, and more. Check out this throw-back article to discover more about how a Schwing Bioset system can help solve your plant\u2019s most challenging issues.<\/strong><\/em><\/h6>\r\n\u00a0\r\n\r\nAlabama\u2019s rich mining tradition\u2014a history that dates back nearly two centuries\u2014and the economic lift it provides (a direct and indirect value of about $5 billion, according to a recent economic census), have not been without their downside. Scars left by once highly productive strip mines dot the countryside, providing harsh contrast to the natural beauty for which the state is known. Efforts to reclaim these sites have been ongoing for some time now, but are really getting a boost of late thanks to the efforts of Jefferson County\u2019s Village Creek WWTP. The Birmingham plant, which once simply landfilled biosolids from its operation, now converts it to a Class \u2018A\u2019 material and uses it to effect area strip mine reclamations. Aided by a pair of KSP 50 sludge pumps from Schwing Bioset (Somerset, WI) which effectively move sludge during one of the fi nal steps in the treatment process, making it ready for shipment, the result has been a win-win for all involved. Land that was once an eyesore, is once again vibrant and pristine, and a material which, in the past, was viewed as\u00a0literally nothing more than a waste product, is helping making that rebirth happen.\r\n\r\nWhole New Approach<\/strong><\/span>\r\n\r\nThe Village Creek WWTP is no slouch when it comes to a history of its own.\u00a0 First built in the early 1900s, it has undergone a series of modifications and expansions over the years, the last of which took place in 2001, essentially reshaping the face of wastewater treatment in the area, according to Terry Lane, the facility\u2019s Plant Manager.\r\n\r\n\u201cTo bring the plant into compliance with the federal Clean Water Act, we added another full plant to operate alongside the existing one.\u00a0 In addition to that, we constructed a series of 20 surge basins to aid in times of peak volume. Doing all this took the plant from a rated capacity of 60 million gallons per day (mgd) to about 420 mgd.\u201d\u00a0 While the basins have a static capacity of 90 million gallons collectively, Lane says that, during those peak times (torrential rains during hurricane season is not uncommon), they can process a huge volume through the newly- configured plant.\r\n\r\n\u201cIt only has a rated capacity of 60 mgd, but we\u2019ve pushed 100 mgd through it with no problem.\u00a0 That\u2019s allowed us to stay ahead of downpours that were associated with hurricanes Ivan, Katrina, and Rita, and that\u2019s saying something.\u201d\r\n\r\nSeparate But Equal<\/strong><\/span>\r\n\r\nProcessing of wastewater at Village Creek is fairly straightforward: sewage is first run past bar screens to remove coarse debris, then pumped into a grit removal system, then on to a primary settling tank.\u00a0 At that point, primary sludge is sent to anaerobic digesters then on for dewatering and biosolids treatment.\u00a0 The balance of the liquid stream heads for secondary aeration, additional filtering and either chlorine or UV disinfection.\r\n\r\n\u201cIt\u2019s important to remember that we actually have two separate plants here, both working at the same time, so when the volume of water comes in, it is split,\u201d says Rob Brown, the facility\u2019s maintenance supervisor.\u00a0 \u201cNot surprisingly, we also have two different types of disinfection at this facility: chlorine on the old side of the plant and ultraviolet on the new side.\u00a0 Because both plants are active, if the chlorine treatment process should go down for some reason, the effluent can be sent here to be treated using the UV.\u201d\r\n\r\nSludge from the digesters is sent to a series of centrifuges for dewatering, then, at a dewatered rate of between 27% and 29% solids, sent via short collection screw conveyors to a Schwing Bioset 10-foot diameter, 940 ft3 sliding frame silo.\u00a0 \u201cThe silo serves as a metering device of sorts,\u201d says Brown. \u201cUsing it in that way allows sludge to be more evenly fed, again via screw feeders, into the Schwing sludge pumps.\u201d\r\n\r\nShort Distance Runaround<\/strong><\/span>\r\n\r\n
![](\"https:\/\/www.schwingbioset.com\/wp-content\/uploads\/2023\/03\/Burmingham-Pump-Cropped.jpg\")
<\/strong>The type of unit at work at Village Creek, Schwing\u2019s KSP 50V(HD)L model, is a piston-style pump that was originally designed for use in concrete pumping projects.\u00a0 It is that demanding application, in fact, that initially drew plant management to select the Schwing pumps to move the dewatered sludge.\r\n\r\n\u201cMy boss at the time was involved in that decision,\u201d says Terry Lane, \u201cand his rationale was simple: he said we had some very dry solids that we had to push a fairly long way\u2014material that would more than likely dry out even more in the lines as it moved.\u00a0 If a pump like that could move concrete, they felt, it could move the dewatered sludge.\u201d\r\n\r\nTo alleviate the issue of dryness, they chose to include Schwing\u2019s pipeline lubrication system to the pipeline.\u00a0 Unlike other systems that inject polymer as the lubricating medium at great expense, Schwing\u2019s system lubricates the pipeline by simply injecting a thin fi lm of water 360 degrees around an annular groove.\u00a0 This system imparts pressure reductions of greater than 50% in the pipeline. \u201cBut it was the power of the pumps, more than anything, that won them over,\u201d says Lane.\r\n\r\nIf laid in a straight line, the distance from the pumps to a pug mill\u2014in which lime is added to the cake before transport\u2014is relatively short: about 50 feet or so.\u00a0 However, that path was straight through a heavily trafficked area which would put workers at risk.\u00a0 To avoid that, the line was instead made to follow the contours of the building.\r\n\r\n\u201cBy doing that we had to take it up some 20-30 feet, have it make a 90\u00b0 turn, snake around and over some storage bins, then route it to the lime machine,\u201d adds Lane.\u00a0 \u201cSo now we are dealing with about 150 feet of pipe rather than 50, and the power of those pumps becomes even more important.\u201d\r\n\r\nIt\u2019s Alive!<\/strong><\/span>\r\n\r\n![](\"https:\/\/www.schwingbioset.com\/wp-content\/uploads\/2023\/03\/Burmingham-Hopper-Cropped.jpg\")
That final step in the process\u2014adding lime to the biosolids\u2014raises pH levels in order to decrease biological activity and reduce pathogen levels. Initially, Village Creek had not planned on needing alkaline stabilization.\u00a0 Lane says nature had other plans.\r\n\r\n\u201cThe original design was intended to be completely thermophilic, which we felt would kill all the bugs, giving us the Class \u2018A\u2019 sludge we needed.\u00a0 At that point we hoped to store it in live-bottom hoppers, drop it directly into the trucks, and haul it out for land application at the mines.\u00a0 Unfortunately, we were one of several plants nationwide that began seeing fecal regrowth.\u00a0 When our sludge went into the thermofluid digesters, the heat was causing the bugs to encapsulate themselves.\u00a0 Generally, once they build that shell, they never come out again.\u00a0 However, after being impacted by a 2700 rpm centrifuge, many of the bugs were coming alive\u2014and doing so in a food-rich environment, which obviously caused them to multiply.\u00a0 So we now add lime which kills any remaining bugs and makes the product ready for transport.\u201d\r\n\r\nNew Lease on Life<\/strong><\/span>\r\n\r\n![](\"https:\/\/www.schwingbioset.com\/wp-content\/uploads\/2023\/03\/CakeTruck-A-cropped.jpg\")
<\/strong>With the biosolid stabilized, it is loaded into dump trucks and hauled to one of several local mines with which the county has contracted to do reclamation.\u00a0 There it is dumped and applied using specialized spreaders.\u00a0 The program has been in place for about ten years now and in that time Village Creek has been sending a steady stream of about a half million pounds of biosolids per week.\u00a0 The results, says Lane, have been impressive.\r\n\r\n\u201cThese locations have become revegetated to such a degree that we are able to grow hay at one of them and use the hay throughout our county departments,\u201d he says.\u00a0 \u201cThis is a recycling program in every sense of the word.\u00a0 We are taking a product that was previously being sent to a landfill, finding a new use for it, growing a new product from it and using that new product\u2014the hay\u2014for road projects, erosion control, fill and so on.\u00a0 In the process we have taken a strip mine that was once a blight on the landscape, and made it a beautiful, vegetated, forested area; it is a superb application for it.\u00a0 And, given the number of mills and mines in this area, we can probably continue to do this for a long, long time. I\u2019d say that\u2019s a pretty good deal for everyone.\u201d\r\n\r\nVisit our website<\/span><\/strong><\/a>\u00a0to read more about our products and solutions, then\u00a0contact us<\/strong><\/a><\/span>\u00a0to learn more about this project or find out how we can help your plant too.\r\n\r\n\u00a0\r\n\r\n[button link=\"https:\/\/www.schwingbioset.com\/downloads\/\" color=\"silver\" newwindow=\"yes\"] Download Our Brochures and Application Reports[\/button]\r\n\r\n[button link=\"https:\/\/www.schwingbioset.com\/news\/\" color=\"silver\" newwindow=\"yes\"] Read More Blog Articles from Schwing Bioset[\/button]","_et_gb_content_width":"","content-type":"","footnotes":""},"categories":[16,276,279],"tags":[214,273,219,181],"class_list":["post-3560","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news","category-mining","category-pump","tag-mining-pumps","tag-paste-backfill","tag-paste-pumps","tag-piston-pumps"],"_links":{"self":[{"href":"https:\/\/www.schwingbioset.com\/es\/wp-json\/wp\/v2\/posts\/3560","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.schwingbioset.com\/es\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.schwingbioset.com\/es\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.schwingbioset.com\/es\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.schwingbioset.com\/es\/wp-json\/wp\/v2\/comments?post=3560"}],"version-history":[{"count":0,"href":"https:\/\/www.schwingbioset.com\/es\/wp-json\/wp\/v2\/posts\/3560\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.schwingbioset.com\/es\/wp-json\/wp\/v2\/media\/3561"}],"wp:attachment":[{"href":"https:\/\/www.schwingbioset.com\/es\/wp-json\/wp\/v2\/media?parent=3560"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.schwingbioset.com\/es\/wp-json\/wp\/v2\/categories?post=3560"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.schwingbioset.com\/es\/wp-json\/wp\/v2\/tags?post=3560"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}