Editing Copper extraction (section)

===Specialized ores===
[[File:Chalcocite-271692.jpg|thumb|A specimen of the mineral chalcocite from the Geevor Mine, Cornwall.]]
Secondary sulfides—those formed by [[Supergene (geology)|supergene]] secondary enrichment—are resistant (''[[refractory]]'') to sulfuric leaching.<ref>{{Cite journal |last=Petersen |first=Jochen |date=October 2016 |title=Heap leaching as a key technology for recovery of values from low-grade ores – A brief overview |journal=Hydrometallurgy |volume=165 |pages=206–212 |doi=10.1016/j.hydromet.2015.09.001|bibcode=2016HydMe.165..206P }}</ref> Secondary copper sulfides are dominated by the mineral chalcocite; a mineral formed from primary sulfides, like [[chalcopyrite]], that undergo chemical processes such as oxidation or reduction.<ref>{{Cite journal |last1=Wu |first1=Biao |last2=Yang |first2=Xinlong |last3=Wen |first3=Jiankang |last4=Wang |first4=Dianzuo |date=2019-11-05 |title=Semiconductor-Microbial Mechanism of Selective Dissolution of Chalcocite in Bioleaching |journal=ACS Omega |volume=4 |issue=19 |pages=18279–18288 |pmc=6844112 |pmid=31720528 |doi=10.1021/acsomega.9b02294 |doi-access=free |issn=2470-1343}}</ref> Typically, secondary sulfide ores are concentrated using froth flotation.<ref>{{Cite journal |last1=Rahman |first1=Reza M. |last2=Ata |first2=Seher |last3=Jameson |first3=Graeme J. |date=November 2013 |title=Froth recovery measurements in an industrial flotation cell |journal=Minerals Engineering |volume=53 |pages=193–202 |doi=10.1016/j.mineng.2013.08.003 |bibcode=2013MiEng..53..193R |issn=0892-6875}}</ref> Other extraction processes like leaching are effectively used for the extraction of secondary copper sulfides, but as demand for copper rises, extraction processes tailored for low-grade ores are required, due to the depletion of copper resources.<ref>{{Cite journal |last1=Yu |first1=Shichao |last2=Liao |first2=Rui |last3=Yang |first3=Baojun |last4=Fang |first4=Chaojun |last5=Wang |first5=Zhentang |last6=Liu |first6=Yuling |last7=Wu |first7=Baiqiang |last8=Wang |first8=Jun |last9=Qiu |first9=Guanzhou |date=January 2022 |title=Chalcocite (bio)hydrometallurgy—current state, mechanism, and future directions: A review |journal=Chinese Journal of Chemical Engineering |volume=41 |pages=109–120 |doi=10.1016/j.cjche.2021.12.014 |s2cid=245562646 |issn=1004-9541}}</ref> Processes including in situ, dump, and heap leaching are cost-effective methods that are suitable for extracting copper from low-grade ores.<ref>{{Cite journal |last=Watling |first=H. R. |date=October 2006 |title=The bioleaching of sulphide minerals with emphasis on copper sulphides — A review |journal=Hydrometallurgy |volume=84 |issue=1 |pages=81–108 |doi=10.1016/j.hydromet.2006.05.001 |bibcode=2006HydMe..84...81W |issn=0304-386X}}</ref>

Extraction processes for secondary copper sulfides and low-grade ores includes the process of heap bioleaching. Heap bioleaching presents a cost efficient extraction method that requires a less intensive energy input resulting in a higher profit.<ref name="Panda-2015">{{Cite journal |last1=Panda |first1=Sandeep |last2=Akcil |first2=Ata |last3=Pradhan |first3=Nilotpala |last4=Deveci |first4=Haci |date=November 2015 |title=Current scenario of chalcopyrite bioleaching: A review on the recent advances to its heap-leach technology |journal=Bioresource Technology |volume=196 |pages=694–706 |doi=10.1016/j.biortech.2015.08.064 |pmid=26318845 |bibcode=2015BiTec.196..694P |s2cid=2254790 |issn=0960-8524}}</ref> This extraction process can be applied to large quantities of low-grade ores, at a lower capital cost with minimal environmental impact.<ref name="Panda-2015"/><ref>{{Cite journal |last=Brierley |first=C. L. |date=December 2008 |title=How will biomining be applied in future? |journal=Transactions of Nonferrous Metals Society of China |volume=18 |issue=6 |pages=1302–1310 |doi=10.1016/S1003-6326(09)60002-9 |issn=1003-6326}}</ref>

Generally, direct [[froth flotation]] is not used to concentrate copper oxide ores, as a result of the largely ionic and hydrophilic structure of the copper oxide mineral surface.<ref name="Feng-2022">{{Cite journal |last1=Feng |first1=Qicheng |last2=Yang |first2=Wenhang |last3=Wen |first3=Shuming |last4=Wang |first4=Han |last5=Zhao |first5=Wenjuan |last6=Han |first6=Guang |date=November 2022 |title=Flotation of copper oxide minerals: A review |journal=International Journal of Mining Science and Technology |volume=32 |issue=6 |pages=1351–1364 |doi=10.1016/j.ijmst.2022.09.011 |s2cid=253788625 |issn=2095-2686|doi-access=free |bibcode=2022IJMST..32.1351F }}</ref> Copper oxide ores are typically treated via chelating-reagent flotation and fatty-acid flotation, which use organic reagents to ensure adsorption onto the mineral surface through the formation of hydrophobic compounds on the mineral surface.<ref name="Feng-2022"/><ref>{{Cite journal |last1=Fuerstenau |first1=D. W. |last2=Herrera-Urbina |first2=R. |last3=McGlashan |first3=D. W. |date=February 2000 |title=Studies on the applicability of chelating agents as universal collectors for copper minerals |journal=International Journal of Mineral Processing |volume=58 |issue=1 |pages=15–33 |doi=10.1016/S0301-7516(99)00058-7 |bibcode=2000IJMP...58...15F |issn=0301-7516}}</ref>

Some supergene sulfide deposits can be leached using a [[bacterial oxidation]] heap leach process to oxidize the sulfides to sulfuric acid, which also allows for simultaneous leaching with sulfuric acid to produce a [[copper sulfate]] solution.<ref>{{Cite journal |last1=Kariuki |first1=Stephen |last2=Moore |first2=Cory |last3=McDonald |first3=Andrew M. |date=March 2009 |title=Chlorate-based oxidative hydrometallurgical extraction of copper and zinc from copper concentrate sulfide ores using mild acidic conditions |journal=Hydrometallurgy |volume=96 |issue=1 |pages=72–76 |doi=10.1016/j.hydromet.2008.08.008 |bibcode=2009HydMe..96...72K |issn=0304-386X}}</ref><ref>{{Cite journal |last1=Robertson |first1=S.W. |last2=Van Staden |first2=P.J. |last3=Seyedbagheri |first3=A. |date=December 2012 |title=Advances in high-temperature heap leaching of refractory copper sulphide ores |url=http://www.saimm.co.za/Journal/v112n12p1045.pdf |journal=Journal of the Southern African Institute of Mining and Metallurgy |volume=112 |issue=12 |pages=1045–1050 |via=ResearchGate}}</ref> For oxide ores, [[solvent extraction and electrowinning]] technologies are used to recover the copper from the [[pregnant leach solution]].<ref name="Ochromowicz-2008">{{Cite journal |last1=Ochromowicz |first1=Katarzyna |last2=Chmielewski |first2=Tomasz |date=January 2008 |title=Growing Role of Solvent Extraction in Copper Ores Processing |pages=29–36 |url=https://www.researchgate.net/publication/228679628 |journal=Fizykochemiczne Problemy Mineralurgii |volume=42}}</ref> To ensure the best recovery of copper, it is important to acknowledge the effect copper dissolution, acid consumption, and gangue mineral composition has on the efficacy of extraction.<ref name="Ochromowicz-2008" />

Supergene sulfide ores rich in native copper are refractory to treatment with sulfuric acid leaching on all practicable time scales, and the dense metal particles do not react with froth flotation media. Typically, if native copper is a minor part of a supergene profile it will not be recovered and will report to the [[tailings]]. When rich enough, native copper ore bodies may be treated to recover the contained copper by [[gravity separation]]. Often, the nature of the gangue is important, as clay-rich native copper ores prove difficult to liberate. This is because clay minerals interact with flotation reagents used in extraction processes, that are then consumed, which results in minimal recovery of a high grade copper concentrate.<ref>{{Cite journal |last1=Han |first1=Baisui |last2=Altansukh |first2=Batnasan |last3=Haga |first3=Kazutoshi |last4=Stevanović |first4=Zoran |last5=Jonović |first5=Radojka |last6=Avramović |first6=Ljiljana |last7=Urosević |first7=Daniela |last8=Takasaki |first8=Yasushi |last9=Masuda |first9=Nobuyuki |last10=Ishiyama |first10=Daizo |last11=Shibayama |first11=Atsushi |date=2018-06-15 |title=Development of copper recovery process from flotation tailings by a combined method of high‒pressure leaching‒solvent extraction |journal=Journal of Hazardous Materials |volume=352 |pages=192–203 |doi=10.1016/j.jhazmat.2018.03.014 |pmid=29609151 |s2cid=4879400 |issn=0304-3894|doi-access=free |bibcode=2018JHzM..352..192H }}</ref>