IM­PACT ROLLERS DO­ING WHAT THEY DO BEST

The Australian Mining Review - - CONTENTS - RAY CHAN

An in­crease in haul truck rolling re­sis­tance has been found to have a sig­nif­i­cant triple ef­fect on costs, ac­cord­ing to a re­cent study. Re­search by Western Aus­tralian School of Mines pro­fes­sor Dr Rodger Thomp­son showed that fuel burn, plant dam­age and cy­cling times all suf­fer at the hands of a poor haul road sur­face.

As high as 50pc of op­er­at­ing costs in open cut mines sit with load­ing and haul­ing, Dr Thomp­son said.

He found three fac­tors of a fail­ing or un­even haul road sent op­er­a­tional costs up. Firstly, the en­ergy re­quired to ‘climb’ the weight out of each de­pres­sion in the road was adding up to 5pc in fuel costs; se­condly, the in­creased cy­cling of sus­pen­sion and fric­tion on tyres was ac­cel­er­at­ing truck main­te­nance; and lastly, the cy­cle times were suf­fer­ing badly.

The study found that the ad­di­tion of only 3pc in rolling re­sis­tance was record­ing up to a 20pc in­crease in seg­ment cy­cling times, pretty damn­ing ev­i­dence that not enough at­ten­tion is be­ing paid to this high cost area of min­ing oper­a­tions.

SQUARE IM­PACT, HIGH IM­PACT

The find­ings have not sur­prised Ade­laide-based roller man­u­fac­turer Broons, which says they were recog­nised by the com­pany long ago and in­deed have been addressed by the re­lease of its Square Im­pact Rollers. For more than three decades, Broons has been sup­ply­ing these rollers to erad­i­cate these ex­act prob­lems; so much so that they have ac­quired leg­endary sta­tus.

The revo­lu­tion­ary patented BH-1300 Roller was re­leased into the world mar­ket in the mid-1980s, quickly be­stow­ing Broons an in­ter­na­tional rep­u­ta­tion as a spe­cial­ist in the ap­pli­ca­tion and op­er­a­tion of rolling dy­namic com­paction equip­ment.

The im­pact mod­ule im­parts a mas­sive 50kJ to 100kJ ki­netic en­ergy (or more, sub­ject to mod­ule mass and width, ground con­di­tions, etc) with ev­ery blow.

With its high en­ergy out­put, the Broons Square Im­pact Roller com­pacts deep be­neath the sur­face in the sub­grade lay­ers to se­cure the haul road struc­ture, pre­vent­ing the for­ma­tion of ‘waves’ so detri­men­tal to haul truck costs.

Even to­day, no al­ter­na­tive com­paction equip­ment comes close to the Im­pact Roller on per­for­mance, pro­duc­tiv­ity and price.

Broons’ ex­pe­ri­ence in dy­namic com­paction is un­equalled any­where around the globe, and has been used by civil en­gi­neer­ing con­trac­tors, prop­erty de­vel­op­ers, min­ing com­pa­nies, state, lo­cal and Fed­eral Gov­ern­ment road agen­cies, forestry sec­tors, and cot­ton and rice grow­ers.

In the min­ing in­dus­try, Broons’ enor­mous BH-1950MS has rev­o­lu­tionised the way to re­duce tyre dam­age and ul­ti­mately con­sump­tion of these ex­pen­sive tyres.

NEVER TOO TYRED

Of course, the more com­pact a road sur­face, the less the wear on tyres. Many com­pa­nies are us­ing Broons Square Im­pact Rollers to flat­ten sur­faces and help re­duce tyre dam­age, and ul­ti­mately save money on wear and tear.

An in­vest­ment in a Roller is quickly re­couped by the sav­ings made from im­proved tyre wear and re­duced dam­age to both the tyres and the haul truck sus­pen­sion.

A num­ber of mines through­out Aus­tralia and over­seas are us­ing the Broons Im­pact Rollers to rub­bilise rock on their tip heads and waste dumps as a way of im­prov­ing their tyre man­age­ment regime.

Ac­cord­ing to Broons di­rec­tor Stuart Bowes, min­ing com­pa­nies are al­ways look­ing for a so­lu­tion to min­imise pre­ma­ture wear and dam­age to haul truck tyres.

“When times are good, high prices and low avail­abil­ity forces them to look for op­tions to ex­tend the life of tyres,” he said. “When re­source prices are low, op­er­at­ing cost sav­ings are the driver for im­prov­ing tyre life….. there’s al­ways a need for our equip­ment.”

Large or sharp rock will slice through and crit­i­cally dam­age even a brand new tyre, while smaller rocks can lodge be­tween the lugs and even­tu­ally pen­e­trate and punc­ture the tyre.

The Broons “MS” (mine spec­i­fi­ca­tion) Im­pact Rollers are world lead­ers in min­imis­ing haul truck tyre wear by im­prov­ing the run­ning sur­face on haul roads, tip heads, and pit floors. Sup­plied as a pack­age with a suit­ably matched tow trac­tor, the Im­pact Rollers quickly re­duce sharp edges and al­low haul trucks to travel eas­ily with­out the fear of tyre dam­age.

An im­proved run­ning sur­face on haul roads and waste dumps has also shown it’s pos­si­ble to re­duce me­chan­i­cal wear and tear on haul truck sus­pen­sion and as­so­ci­ated com­po­nents, de­liv­er­ing lower over­all main­te­nance costs.

COM­PACTION AND CAP­PING

The Im­pact Rollers have also been em­ployed in many other ap­pli­ca­tions, in­clud­ing the com­paction of cap­ping lay­ers on waste dumps, where the equip­ment has proven to be both pro­duc­tive and cost-ef­fec­tive.

Cap­ping lay­ers are typ­i­cally used to re­duce the like­li­hood of spon­ta­neous com­bus­tion coal waste and over­bur­den, or the in­fil­tra­tion of sur­face water through mine waste that can lead to en­vi­ron­men­tal prob­lems with drainage and runoff.

Water in­fil­tra­tion and/or the con­vec­tive trans­port of oxy­gen into a dump

can be re­duced to very low lev­els by con­struct­ing a low per­me­abil­ity com­pacted cover over the dump.

Tri­als and on­go­ing use have shown that by plac­ing around one me­tre of in­ert ma­te­rial over the waste and then com­pact­ing with the Square Im­pact Rollers will pay div­i­dends.

Stud­ies un­der­taken by Dr Mark Jaksa and Bren­dan Scott of the School of Civil, En­vi­ron­men­tal and Min­ing En­gi­neer­ing at the Univer­sity of Ade­laide have also shown that by us­ing a sin­gle thicker cap­ping layer, greater re­cy­cling of mine spoil ma­te­ri­als can be used with­out the need to screen out large quan­ti­ties of over­sized ma­te­ri­als.

Deep fills have tra­di­tion­ally been un­der­taken by com­pact­ing soil in thin lay­ers us­ing rel­a­tively small sized ma­te­rial placed in a highly con­trolled man­ner.

While con­ven­tional rollers can sat­is­fac­to­rily com­pact fill in lay­ers up to 400mm thick­ness, stud­ies at mine sites have shown that the Im­pact Roller can typ­i­cally achieve thick-lift com­paction in lay­ers of 500-1500mm, depend­ing on the ma­te­rial com­po­si­tion and the num­ber of passes by the roller.

With just six to 10 passes ap­plied on the sur­face, im­prove­ment in den­sity can oc­cur to at least one me­tre, while 30-40 passes can re­sult in sig­nif­i­cant im­prove­ment down to 2m and be­yond in some ma­te­ri­als.

The Square Im­pact Roller was also used in tri­als in Emer­ald, Queens­land, aimed at cre­at­ing a cap­ping layer over mine waste. En­sham Re­sources used a BH1300 (8t mod­ule) and a BH-1300HD (12t mod­ule) over a 40,000m2 trial area, plan­ning to achieve a low per­me­abil­ity cap­ping layer.

En­sham hopes to re­in­state close to 150ha of the open-cut coal mine to flood plain con­di­tions. Re­sults from the tri­als were ob­tained to de­ter­mine the most ef­fi­cient method to meet strict en­vi­ron­men­tal and en­gi­neer­ing re­quire­ments for the on­go­ing place­ment and com­paction of cap­ping lay­ers.

HEADS UP ON TAIL­INGS

Broons Im­pact Rollers were used by Cooks Con­struc­tion to carry out lay­er­ing work for the Cen­tury Zinc mine in Lawn Hill, Queens­land, one of the largest zinc mines in the world.

With sev­eral tail­ings dams at the site rang­ing from 50m to 1000m in length, and vary­ing in height from 5m to 30m, stor­age ca­pac­ity will to­tal 56m m3 of tail­ings de­posits when com­plete.

Con­cerns about the in-situ den­si­ties of the earth­fill re­sulted in the need for com­pleted lay­ers to be proof-rolled prior to the place­ment of sub­se­quent lay­ers.

Broons BH-1300 (8t mod­ule) ma­chines suc­cess­fully proof-rolled com­pleted lay­ers pre­vi­ously com­pacted with vi­brat­ing rollers, en­sur­ing ab­so­lute con­fi­dence in the in­tegrity of the dam, while iden­ti­fy­ing soft spots for treat­ment.

GO­ING THE DIS­TANCE

With the con­tin­ued glob­al­i­sa­tion of min­ing and con­struc­tion com­pa­nies, there can be oper­a­tions across many time zones.

Broons em­ploys so­phis­ti­cated trans­port in­fra­struc­ture to sup­port the de­mands of its truly in­ter­na­tional cus­tomers. Since the 1980s, the man­u­fac­turer has been send­ing the Square Im­pact rollers via road, rail, sea and even air, to meet the de­mand from com­pa­nies the world over.

Of­ten matched with suit­able trac­tors, the ma­chines can be stripped down for the most ef­fec­tive pack­ag­ing.

“Given most of our clients work in re­mote re­gions, the trans­port costs can be sig­nif­i­cant so our oper­a­tions team spend a lot of hours find­ing the best trans­port so­lu­tion,” Mr Bowes said.

“Of­ten this can be dic­tated by the ur­gency of the need for the equip­ment. “In the Mid­dle East we flew 25 units with trac­tors, which was un­prece­dented; but our clients were work­ing just three days af­ter the equip­ment left our shores.” Do­mes­ti­cally, long haul road freight into WA from the east can be ex­pen­sive but Broons re­cently part­nered with SCT Lo­gis­tics to pro­vide a cost-ef­fec­tive so­lu­tion us­ing the rail ser­vice across the Nullar­bor.

AVAIL­ABIL­ITY

The rollers have been revered world­wide for transformi­ng haul roads, with their deep com­paction, low main­te­nance and speed to sites.

Cost­ing a frac­tion of the sav­ings to be made, a Square Im­pact Roller with matched tow trac­tor is ready for hire or pur­chase now, from Broons’ ex­ten­sive Aus­tralia-wide fleet. Broons is renowned for its com­mit­ment to cus­tomer ser­vice, and pro­vides full in-field op­er­a­tor train­ing and ser­vice to the in­dus­try, backed up with a com­pre­hen­sive and prompt parts op­er­a­tion.

Re­sis­tance is fu­tile.

A Broons Im­pact Roller do­ing what it does best: break­ing rocks.

A tyre dam­aged by driv­ing on rocks.

An ex­am­ple of tyre wear caused by driv­ing on poor con­di­tion roads.

Rock and roll: A be­fore-and-af­ter com­par­i­son of rocks af­ter they’ve been rolled.

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