8/17/2019 One Mine

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One Mine's Nickel Processing of Pyrrhoite,Chalcopyrite and Pentalandite Ores

The ore is crushed to -5 inches in primary cone crushers, then reduced to -1 !" in short head conecrushers# The ore is then ground to -1$$ mesh in %all mills# &sing et magnetic separators the magneticore is separated (pyrrhotite) and further reduced to -!$$ mesh in a %all mill# Classification is accomplished

ith screens and cyclones# The pyrrhotite is then sent to froth flotation cells, and produces a *+ nickelconcentrate#

The non magnetic ore is sent to a series of rougher, cleaner flotation cells, and produces a *1+ copperconcentrate# The tailings from these cells is sent to another flotation cell, to reco er the nickel, and theconcentrate is com%ined ith the *+ nickel concentrate to produce a 1!+ nickel concentrate#

Most nickel ores ha e se eral reco era%le metals in them and the process if commonly a multiple streamof metals reco ered# The copper concentrate is sent to the copper smelter and # + copper cathode is

produced in electro inning cells# The nickel ore is sent to the nickel refinery, here a comple. set ofreactions is carried out# These include leaching in autocla es using ammonia, heated to around !$$ deg/ at ele ated pressures of 1$$-15$ P0 # The application of heat and pressure dramatically speeds up thechemical reaction and produces the nickel much faster than leaching at room temperature andatmospheric pressure# There is a primary and a secondary leach circuit, here the solids remaining in thefirst circuit are sent to a second autocla e to reco er any metals the first leach process missed# 2 slurry of the li3uid and solids are then pumped through a thickening and filtration system, separating the non-

alua%le solids from the li3uid containing the nickel# The nickel and ammonia solution contains !4! ratio of nickel to ammonia (molar), hich is roughly 5$ grams nickel per liter of solution#

The nickel-ammonia solution is then reduced ith hydrogen in autocla es, adding a a small amount offerrous ammonium sulphate# This solution is heated to !5$ deg / at *5$ P0 , in a hydrogen atmosphere#The nickel is reduced %y hydrogen and precipitates as fine metallic nickel (Ni)# The nickel settles and thesolution is pumped out to a holding tank# 0ince the solution still contains some nickel , it is re-processedagain to reco er the remaining nickel# The nickel can then %e remo ed through a cone %ottomed tank or%y a thickener filter operation to yield the nickel po der# t is then dried and sent to a %ri3uette process

here it is made into pellets or %ri3uettes# t can also %e melted and poured into ingots for sale to themarket#

nformation pro ided %y Charles u%ach, Mining and Mineral Processing 6ngineer