announced in February this year<\/a>, has opened up new pathways for optimising beneficiation performance and supporting more sustainable, resource-efficient mineral processing.<\/p>\n\u201cVRM technology has got a long history and was invented by Loesche almost 100 years ago,\u201d he said. \u201cLoesche has got more than 2,400 operating references in cement and other industry applications such as blast furnace slag grinding.<\/p>\n
\u201cPalabora in South Africa put it to work on rock phosphate and there have been other applications there.<\/p>\n
\u201cThe time was right for us commercially but on the customer side there\u2019s obviously the continuing emphasis on energy, carbon and water and this really ticks all the boxes. We\u2019ve seen 40%-plus improvements in energy efficiency in some cases.<\/p>\n
\u201cAnd we can operate with a coarse secondary crushed feed and grind down to the final grind size, so we\u2019re substituting most of the [conventional] grinding and eliminating all that grinding media and mill lining wear associated with conventional grinding mills. Downstream processes also benefit from improved mineral liberation and steeper particle size distribution. Wear inside the [VRM] unit is very low: a fraction of the total wear mass per tonne compared to conventional grinding technologies.<\/p>\n
\u201cDry comminution means we can optimise water addition to the downstream plant, assuming it\u2019s a wet beneficiation process, or otherwise integrate it seamlessly in a dry beneficiation process. Flowsheets with coarse particle flotation, magnetic separation or other coarse beneficiation technologies can be facilitated. We are talking about reducing or even eliminating water consumption if fully dry processes are feasible.<\/p>\n
\u201cThere are a lot of dry magnetic separation technologies that are coming on through the market these days. We see a role in enabling that.<\/p>\n
\u201cIt\u2019s much more efficient than dry ball milling or any other technology for those applications.<\/p>\n
\u201cClearly a dry feed is optimum for a roasting application and then another attractive application is across hematite and magnetite iron ore producing a pelletising feed.<\/p>\n
\u201cWe do also have some interest in using the VRM on pebble circuits and pebble stockpile processing. We can deliver the product directly, for example, to a ball mill sump or cyclone feed hopper so we\u2019re essentially producing final product from the mill pebbles. That will relieve the SAG mill, but also the ball mill, from the hardest material in the process.\u201d<\/p>\n
The CEEC Medal-winning Metso Loesche paper on the benefits of combined VRM-coarse flotation early gangue rejection put a spotlight on industry-first development by Metso and Loesche of an integrated grit recirculation system and on important test work at Metso Loesche\u2019s Ore Grinding Plant (OGP) pilot facility in South Australia.<\/p>\n
Advances in hydrodynamics and process chemistry are increasingly pushing new coarse particle flotation (CPF) technologies to the fore. Nielsen says energy and water efficiency benefits of early waste material classification are also gaining currency.<\/p>\n
\u201cThere\u2019s a lot of interest in that coarse gangue rejection stage,\u201d he said.\u00a0\u201cConventional comminution circuits are not a great fit for certain-size material in part because classification at the target particles sizes is difficult. Targeting 300-500 microns is really too fine for screens at large scales and right up towards the coarse end of what\u2019s feasible to achieve with a hydro-cyclone.<\/p>\n
\u201cWith the VRM we can produce that size fraction fairly easily and we do that with grit extraction. Grit is the oversized particles from the classifier in the vertical roller mill. Instead of returning those oversized particles to the table we can extract them and send them to coarse particle flotation or magnetic cobbing or other coarse beneficiation technologies.<\/p>\n
\u201cCPF is really very interesting for us because we\u2019re also taking the fines out of that material, so it\u2019s easier to handle and easier to process with CPF. And then there\u2019s still the fine product from the vertical roller mill that would go directly to flotation stages and that can be combined with a CPF concentrate via regrinding as well.\u201d<\/p>\n
Nielsen will be available at Metso\u2019s IMARC stand with a flowsheet showing what that looks like.<\/p>\n
\u201cIt\u2019s potentially a big enabler of CPF,\u201d he said.<\/p>\n
While incumbent technologies, including horizontal mills, will continue to be mining\u2019s comminution workhorses, Nielsen will explore how miners can draw on a broad portfolio of flowsheet solutions, including combinations of HPGRs and stirred mills, to help them balance capital cost, operating cost, reliability, availability and sustainability.<\/p>\n
\u201cI think the bottom line is that there are technologies and flowsheet arrangements available today that are cost-effective in terms of total installed cost but also provide the availability, operating cost and sustainability benefits the industry is looking for.\u201d<\/p>\n
*Richard Roberts is Editorial Director of Beacon Events<\/p>\n","protected":false},"excerpt":{"rendered":"A 20-year-plus veteran of the mineral comminution business, Bjorn Nielsen is excited about what lies ahead for the…\n","protected":false},"author":2,"featured_media":665840,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6],"tags":[282024,282025,282026,282027,282028,61,282029,60,282030,282031,282032,80,282033],"class_list":["post-665839","post","type-post","status-publish","format-standard","has-post-thumbnail","category-technology","tag-beneficiation","tag-bjorn-nielsen","tag-coarse-flotation","tag-dry-comminution","tag-hpgrs","tag-ie","tag-imarc","tag-ireland","tag-loesche","tag-ore-grinding-plant","tag-palabora","tag-technology","tag-vrms"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/665839","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/comments?post=665839"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/665839\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media\/665840"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media?parent=665839"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/categories?post=665839"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/tags?post=665839"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}