Faced with in­creased pro­duc­tion de­mands, Com­pañía Min­era Doña Inés de Collahuasi had the goal of in­creas­ing both the avail­abil­ity and per­for­mance of its ver­ti­cal plate pres­sure fil­ters (VPA) in Puerto Pat­ache, which were be­com­ing out­dated after more than


In col­lab­o­ra­tion with Metso, Collahuasi de­vel­oped an up­grade plan based on us­ing state-of-the-art tech­nol­ogy; the de­sired ob­jec­tives were met and re­sulted in a 15 per cent in­crease in fil­ter avail­abil­ity.

THE pro­ject was car­ried out at Collahuasi’s mine in north­ern Chile, about 180km south­east of the port of Iquique, at an al­ti­tude of 4400m.

This min­ing dis­trict has been in business since 1880 with the ex­por­ta­tion of high-grade cop­per-sil­ver vein sys­tems.

Cur­rently, it is ded­i­cated to the ex­trac­tion and pro­duc­tion of cop­per and molyb­de­num con­cen­trate.

Dur­ing 2016, Collahuasi was the third-largest cop­per op­er­a­tion in the world and has one of the largest de­posits of min­eral re­sources of cop­per on the planet (9.964 mil­lion tonnes). Its share­hold­ers are An­glo Amer­i­can plc (44 per cent), Glen­core (44 per cent) and Japan Collahuasi Re­sources B.V. (12 per cent).

Collahuasi was fac­ing the great chal­lenge, com­mon to many global min­ing groups, of op­ti­mis­ing its op­er­a­tions to achieve the high­est lev­els of ef­fi­ciency.

“In or­der to en­sure pro­duc­tiv­ity and profitabil­ity in the fu­ture, Collahuasi has de­cided to de­velop a pre­ven­tive main­te­nance im­prove­ment pro­gram, which is com­prised of a master plan to max­i­mize avail­abil­ity and min­i­mize bot­tle­necks, through a long-term and sus­tain­able approach. Its ob­jec­tive is to de­tect po­ten­tial prob­lems in ad­vance and max­i­mize the per­for­mance and avail­abil­ity of ex­ist­ing equip­ment,” Col­la­hausi vice pres­i­dent for pro­cesses Dal­i­bor Drag­ice­vic said.

In ad­di­tion to the VPA fil­ters, Collahuasi also has other equip­ment from Metso such as semi-au­to­ge­nous ( SAG) grind­ing mills, ball mills, and Ver­timills.

Age­ing equip­ment poses a chal­lenge

Thanks to the col­lab­o­ra­tive re­la­tion­ship be­tween Collahuasi and Metso, a joint di­ag­nos­tic meet­ing was held to re­view the main needs and po­ten­tial im­prove­ment to the fil­trate-con­cen­trate level, which was re­lated to the re­quire­ments of its VPA ver­ti­cal fil­ters to in­crease their pro­duc­tion ca­pac­ity while also in­creas­ing the over­all re­li­a­bil­ity of the sys­tem.

Due to the high pro­duc­tiv­ity re­quire­ments and over 20 years of use since its in­stal­la­tion, the fil­ters were show­ing a high de­gree of wear and mis­align­ment, which re­duced their avail­abil­ity due to the extra main­te­nance re­quired by the fil­ters and con­sid­er­able un­planned down­time.

Dur­ing the re­view stage of the over­haul, a joint de­ci­sion was made to im­prove and up­grade the con­trol sys­tems, lu­bri­ca­tion and struc­ture of the equip­ment in or­der to achieve higher lev­els of avail­abil­ity.

Equip­ment re­fur­bished to as new con­di­tion

The chal­lenge for Metso re­sulted in up­grad­ing the con­trol sys­tems to the lat­est tech­nol­ogy, achiev­ing val­ues of over 92 per cent avail­abil­ity and 100 per cent of de­sign ca­pa­bil­ity.

This in­volved re­in­stalling and up­grad­ing equip­ment in less than 20 days to min­i­mize lost pro­duc­tion.

The en­gi­neer­ing co­or­di­na­tion, parts pro­cure­ment and plan­ning ac­tiv­i­ties be­gan six months ear­lier in or­der to en­sure the com­plete com­pat­i­bil­ity and suc­cess­ful out­come of this up­grade.

Com­pre­hen­sive tech­no­log­i­cal so­lu­tion

The ex­ten­sive up­grade of the equip­ment in­volved mul­ti­ple steps. The Metso team first pro­posed im­prov­ing the orig­i­nal de­sign ca­pac­ity by up­dat­ing com­po­nents and sys­tems to pro­duce some im­por­tant ben­e­fits.

For this, Metso fo­cused on the main prob­lems that were caus­ing the struc­tural mis­align­ment of the fil­ters. In or­der to solve the struc­tural prob­lems, the fil­ter was com­pletely dis­as­sem­bled and over 80 per cent of its parts were re­placed with new parts us­ing a nanocoat­ing tech­nol­ogy for cor­ro­sive en­vi­ron­ments.

Us­ing this approach would dou­ble the life­span of the key parts and com­po­nents and re­duce po­ten­tial down­time.

In or­der to achieve the op­ti­mal se­lec­tion of fab­ric, a pi­lot fil­ter was im­ple­mented at the work­site to take sam­ples of con­cen­trate. The sam­ples were then used to help de­fine the proper fab­ric for the fil­ter­ing process given the spe­cific min­eral con­di­tions that Collahuasi was pro­cess­ing.

In many sit­u­a­tions, th­ese types of tests in­volve us­ing Metso lab­o­ra­to­ries lo­cated in Brazil and Fin­land. How­ever, with the pi­lot fil­ter on site, it was pos­si­ble to per­form all the tests in situ with the client, im­prov­ing the se­lec­tion and mak­ing it eas­ier and quicker to get the re­sults.

An­other tech­no­log­i­cal im­prove­ment in­tro­duced was the im­ple­men­ta­tion OCS-4D, an ad­vanced process con­trol so­lu­tion.

The so­lu­tion as­sisted in de­ter­min­ing the op­ti­mal con­trol modes through an­a­lyz­ing the in­ter­play be­tween the se­lec­tion of fab­rics and main­te­nance events.

Fi­nally, the chute was also ex­am­ined for pos­si­ble im­prove­ment op­por­tu­ni­ties. As the VPA fil­ters dis­charge the fil­tered ma­te­rial (cake) into the chute, it was sub­jected to high rates of wear, caus­ing a re­duc­tion in per­for­mance. Var­i­ous designs and op­tions were ex­am­ined to im­prove ease of main­te­nance and thus re­duce down­time.

“Search­ing for a de­sign that im­proved main­tain­abil­ity, we im­ple­mented new, mod­u­lar de­sign up­grades to the chute, so that it could re­ceive main­te­nance section by section,” Min­er­als Process Equip­ment man­ager Ale­jan­dro Bravo said.

“Thus, when a spe­cific part shows signs of wear, we can dis­as­sem­ble that part and change it quickly.

“This is also an im­prove­ment that was tailored for the client, given that with the orig­i­nal de­sign we had to dis­as­sem­ble the en­tire equip­ment to be able to change some parts.”

Ex­pand­ing the pro­ject

Given the suc­cess of the pro­ject, Min­era Doña Inés de Collahuasi SCM is eval­u­at­ing the im­ple­men­ta­tion of the same up­grade con­cept in other VPA fil­ters as part of its as­set man­age­ment plan.

“With this so­lu­tion, we have been able to meet some of the avail­abil­ity goals we set for 2017. The fil­ter to­day works ac­cord­ing to the plans drawn up with Metso, which helps us to con­tinue op­er­at­ing ef­fi­ciently,” Col­la­hausi Symp­to­matic Process se­nior en­gi­neer Cris­tián Bar­ros said.

Changing the plates of the fil­ter.

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