Mining Iron Ore from Tailings with Minimal Use of Process Water

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Abstract

Iron ore tailings typically containing 40 to 50% Fe can be beneficiated to iron ore products containing 54 to 60% Fe. The impurities are comprised of clay, quartz, cristabolite and TiO2. Goethite and hematite are also present. At high concentrations of 55-60 wt% solids, the tailings displayed high yield stress and viscosity and cannot be pumped over long distances. Composite additives comprising of NaOH, phosphate-based additives and sodium metasilicate are found to reduce the viscosity and yield stress very significantly by a few orders of magnitude. The yield stress of 100 Pa can be reduced to almost zero. At this state, dilution of the tailings with its process water to 40% solids causes the coarse and high-density iron ore particles to separate from the colloidal fractions located in the supernatant after a few minutes of sedimentation. Separation by decantation produces a sediment with an Fe content of 54% from tailings with 47% Fe. Another tailings sample with 48% Fe was beneficiated to greater than 57% Fe using NaOH-metasilicate-polyphosphate additives and employing an additional washing step. The use of other composite additives, NaOH and polyphosphates, increased beneficiated product Fe content to greater than 60% from the same tailings. With the current iron ore spot price of more than US$180 per tonne, the cost of this treatment process even including a desalination step if necessary, is relatively insignificant. This study has given tailings an economic value that should be exploited as soon as possible.
Original languageEnglish
Pages654
Number of pages660
Publication statusPublished - 8 Nov 2021
EventIronOre 2021 - Australia, Perth, Australia
Duration: 8 Nov 202110 Nov 2021
https://www.ausimm.com/conferences-and-events/iron-ore/

Conference

ConferenceIronOre 2021
Country/TerritoryAustralia
CityPerth
Period8/11/2110/11/21
Internet address

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