Editing Iron ore (section)

== Mine tailings ==
For every one ton of iron ore concentrate produced, approximately 2.5–3.0 tons of iron ore [[tailings]] will be discharged. Statistics show that there are 130&nbsp;million tons of iron ore tailings discharged every year. If, for example, the mine tailings contain an average of approximately 11% iron, there would be approximately 1.41&nbsp;million tons of iron wasted annually.<ref name=":0">{{Cite journal |title=Innovative methodology for comprehensive utilization of iron ore tailings: Part 1. The recovery of iron from iron ore tailings using magnetic separation after magnetizing roasting |issue=1–3 |pages=71–77 |last1=Li |first1=Chao |last2=Sun |first2=Henghu |date=2010-02-15 |journal=Journal of Hazardous Materials |volume=174 |last3=Bai |first3=Jing |last4=Li |first4=Longtu |doi=10.1016/j.jhazmat.2009.09.018 |pmid=19782467|bibcode=2010JHzM..174...71L }}</ref> These tailings are also high in other useful metals such as [[copper]], [[nickel]], and [[cobalt]],<ref>{{Cite journal |last1=Sirkeci |first1=A. A. |last2=Gül |first2=A. |last3=Bulut |first3=G. |last4=Arslan |first4=F. |last5=Onal |first5=G. |last6=Yuce |first6=A. E. |date=April 2006 |title=Recovery of Co, Ni, and Cu from the tailings of Divrigi Iron Ore Concentrator |journal=Mineral Processing and Extractive Metallurgy Review |volume=27 |issue=2 |pages=131–141 |doi=10.1080/08827500600563343 |bibcode=2006MPEMR..27..131S |s2cid=93632258 |issn=0882-7508}}</ref> and they can be used for [[Road building|road-building]] materials like pavement and filler and building materials such as cement, low-grade glass, and wall materials.<ref name=":0" /><ref>{{Cite journal |title=Exploitation of iron ore tailing for the development of ceramic tiles |issue=8 |pages=725–729 |journal=Waste Management |volume=20 |doi=10.1016/S0956-053X(00)00034-9 |date=December 2000 |last1=Das |first1=S.K. |last2=Kumar |first2=Sanjay |last3=Ramachandrarao |first3=P.|bibcode=2000WaMan..20..725D }}</ref><ref>{{Cite journal |last1=Gzogyan |first1=T. N. |last2=Gubin |first2=S. L. |last3=Gzogyan |first3=S. R. |last4=Mel’nikova |first4=N. D. |date=2005-11-01 |title=Iron losses in processing tailings |journal=Journal of Mining Science |volume=41 |issue=6 |pages=583–587 |doi=10.1007/s10913-006-0022-y |bibcode=2005JMinS..41..583G |s2cid=129896853 |issn=1573-8736}}</ref> While tailings are a relatively low-grade ore, they are also inexpensive to collect, as they do not have to be mined. Because of this, companies such as [[Magnetation (iron ore)|Magnetation]] have started reclamation projects where they use iron ore tailings as a source of metallic iron.<ref name=":0" />

The two main methods of recycling iron from iron ore tailings are magnetizing roasting and direct reduction. Magnetizing roasting uses temperatures between {{convert|700|and|900|C|abbr=on}} for a time of under 1 hour to produce an iron concentrate (Fe<sub>3</sub>O<sub>4</sub>) to be used for iron smelting. For magnetizing roasting, it is important to have a reducing atmosphere to prevent oxidization and the formation of [[Iron(III) oxide|Fe<sub>2</sub>O<sub>3</sub>]] because it is harder to separate as it is less magnetic.<ref name=":0" /><ref>{{Cite journal|last1=Uwadiale|first1=G. G. O. O.|last2=Whewell|first2=R. J.|date=1988-10-01|title=Effect of temperature on magnetizing reduction of agbaja iron ore|journal=Metallurgical Transactions B|volume=19|issue=5|pages=731–735|doi=10.1007/BF02650192|issn=1543-1916|bibcode=1988MTB....19..731U|s2cid=135733613}}</ref> Direct reduction uses hotter temperatures of over {{convert|1000|C|abbr=on}} and longer times of 2–5 hours. Direct reduction is used to produce [[Direct reduced iron|sponge iron]] (Fe) to be used for steel-making. Direct reduction requires more energy, as the temperatures are higher and the time is longer and it requires more reducing agent than magnetizing roasting.<ref name=":0" /><ref>{{Cite journal |last1=Stephens |first1=F. M. |last2=Langston |first2=Benny |last3=Richardson |first3=A. C. |date=1953-06-01 |title=The Reduction-Oxidation Process For the Treatment of Taconites |journal=JOM |volume=5 |issue=6 |pages=780–785 |doi=10.1007/BF03397539 |issn=1543-1851 |bibcode=1953JOM.....5f.780S}}</ref><ref>H.T. Shen, B. Zhou, et al. "Roasting-magnetic separation and direct reduction of a refractory oolitic-hematite ore" ''Min. Met. Eng.'', 28 (2008), pp. 30-43</ref>