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-1- <br />~. Leeching operations ere dilflculc under cold c11.at1c conditient. <br />S. glnsing o[ contarinated latch solutions from the heap •Lter it <br />reaches its tins] he/the 1s d!!flcult, sloe end erpenslra. Rein <br />utter inflleneion can cruse coot ulneced alllnanes to bleed from <br />the Aeap !or )an. <br />6.. large lnrentorles o1 {old ere tied up 1e the unleashed ores and <br />pregnnt solutions in these heaps !or long periods of LSu. <br />CFL.ULAR HGtP LEACHING <br />Cd1uLr Nnp Leaching ewbines chs •ttrl6uue 01 nth o1 tM other cvo <br />systa» co gf re an anti ronrentally-secure, e[flcient and luv-coat s)acer. <br />Dasicall), Cellular Heap Leaching consists o! toning a tall, rut ti-layered <br />heap with •n internal cellular structure. 'Intenslre, unf ion and controlled <br />lemching, rinsint ~snd neutrell:ation occur Sn the cells in [he top layer of the harp. <br />All o! the underlTing cell layers are fort cite and receir• onlT ^ small count <br />o[ rain fnfiltn elan from.the side area o! the heq. Cell lgers •re sepante0 <br />b) •n i.perrfoua PPC I0.mi1 lining and the cells are delln:aced D) PTC located , <br />df rt berms on the tops and bottors o[ the cells. Cells in the cop layer are <br />succesairel7 filled with crushed ore, leached by dovnverd percolation oL strong <br />-nd weak solo [loos Sn • progressive, mul tl-stage canner until tAe utlsum «onwle <br />reco•ery of the ore fs reached end then rinsed and neutrelfred until the effluent <br />from the cell !a clean enough co teat sec standards. The nerc orerl)ing cell <br />boteom acts •s en imperrioua cop eo the underlying cell. The ore bed thickne» <br />in the cells Sa usually 6ecueen 10 and 35 feet. Internal plwbfns syatew remote <br />pre{nape leach liquors from the [ell bottoms and dellrer fresh ]tech solutlona <br />to the cope o[ the tells, The Oregnent solution recovery system can also be <br />used to monitor the entln heap on • cell-Drce11 b»1s. Flturn 2 through S <br />and references (1) througA (S) describe the conatruetlon and operation of these <br />er stemsin greater detail. <br />Preferably, solution addition !s best Jone b) flooding 6er.ed sections vlthis <br />the cell tope. fig- ~•ducea evaporation losses, contains rain and snovmelt caters <br />until the) can 6e used 6y the syster, proridea en ice cap co the cell tope in <br />vlntertiee, prorldes a higA degree of unllormicy 1n solution dl sect button and <br />percolation and eltminates much o! the hand labor riot !a asaoclated vlth <br />sprinkling systems. In the Brent that an ore is tee porous, it Y) be necessary <br />to place • [Ain layer e! ova fines on the cep surlsea e! the ore bed to regulate <br />eke per[ol«fon net. <br />fie cellular seruetun o! this state. should cake it pouibla to use • <br />nee teens o[ solution-ore contact. In the suthor'• 'Stacie Leach' concept, <br />-~- <br />llms is added co the ore 1n the crushing step end a limited amount of strong <br />cyanide solution !s added to • cell of fresh ore ao •s to chorouiblT vet ft. <br />:egula: /each eet„cf ens ere oetcoleted througA the cell bed sererol veeka or <br />months later to close out the strong pregnant eolutlons. This type o[ 1n-cell <br />'curln~'should aignificanclT reduce leeching coats end slrpllf) coldwesther <br />operations. <br />This ryscer hta • tremendous upaci t) to store leach solutlona and clam <br />fain eaters vSthln it, 7[ cAe 6occom «ll layer fa designed vlth 8-Coot high <br />m rector end interior cell Derma, then all of the cells !n this fryer here <br />sn interstitlel storage volume o[ about 1.6 acre ft. of solutl on or eater per <br />acre o[ pad area. One or more of the bottom cells can be used per top cell <br />that is befog leeched or rinsed co store ell of the solutions being used 1n these <br />top cells end the rest of the 6occom cells can east if hold the rein that • <br />would in[iltrste the system from a sudden 13-l nth downpour. Also, lnec ti re <br />top cells ten 6e covered b) the nezt orerl )ing cell bottom liners and ell <br />rain that [ells on them ceu be aeperetel) vlthdrevn and discharged dl cacti) <br />to the environment. These corered lnectlre cell toga ten el so 6e used to <br />store up to two feet of voter or leach solutions. <br />Another lmpor tent character] sett o[ the CH Leech] ng s)seem is chat it <br />is deelgned to octet produce contaminated solutions that could enter the <br />underlying groundveters. The rein caters that fell on the corered top Snactlre <br />cal le can be selectirelT vi thdravn from [he sTStem end those that fa]] on <br />the sides of the heap would trerel through only a smell fret elan of the <br />•olume o[ the rinsed end neutrellzod tai ]logs within the heap before the) <br />you ld be removed. During the period that the heap is bef ng formed and leached, <br />these solutions would De used as nekeuD voters. B) the time the heap 1s <br />completed, the side fn[iltretf on zones should be ao well rinsed that heap <br />offluents should meet drf nki ng eater standards. This should el Sml nece the <br />need for ^ol ution treatment fec111ties at most, 1f no[ ell, sites. <br />A large nusber o[ long-ter. Cellular Neep Leech le bore tor) column testa <br />Aare been performed on ores fros man) different heap leach] ng opera cfons(I), <br />In virtually ever) case, gold end •il•er recorerfea were 6ecueen S and IO percent <br />better and c)anl de and lime consumptlona ve re appreclabl) less then the «cutl <br />plant operrtlons. A smell commercial C11 Leech plant vas bull[ and opera red on <br />old, fine l)-ground gold mill callings !n Ctncrsl Idaho fn the earl) 19g0't.(I) <br />Although unespected percolation pro4leaa ve re experienced, the go10 recover) <br />aces closely rocched chose o[ the Lboncory cesu. <br />Cellular Nesp Leaching is more en•ironmentelly-secure cAan the ocher cvo <br />leaching systems for ^ nwber of reasons. First, in CH Leaching only • <br />• r <br />