Abstract
Excessive TiO2 in titanomagnetite concentrates (TC) causes unavoidable problems in subsequent smelting. At present, this issue cannot be addressed using traditional mineral processing technology. Herein, a strategy of metallurgy-beneficiation combination to decrease the TiO2 grade in TC before smelting was proposed. Roasting TC with calcium carbonate (CaCO3) together with magnetic separation proved to be a viable strategy. Under optimal conditions (roasting temperature = 1400 °C, CaCO3 ratio = 20%, and magnetic intensity = 0.18 T), iron and titanium was separated efficiently (Fe grade: 56.6 wt.%; Fe recovery: 70 wt.%; TiO2 grade 3 wt.%; TiO2 removal: 84.1 wt.%). X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy analysis were used to study the mechanisms. The results showed that Ti in TC could react with CaO to form CaTiO3, and thermodynamic calculations provided a relevant theoretical basis. In sum, the metallurgy-beneficiation combination strategy was proven as an effective method to decrease unwanted TiO2 in TC.
Highlights
As high-grade iron ores are gradually depleted, titanomagnetite is used as an alternative ore for steel smelting [1,2]
Sodium salt-roasting direct reduction is used in smelting, but this process consumes a large amount of sodium salt, resulting in high cost [12,13]
The three indicators decreased to varying degrees, which were attributed to the phase transformation Minerals 2021, o11f, xmFOaRgPnEeEtRicREirVoIEnWto nonmagnetic iron in the oxidizing atmosphere [20]
Summary
As high-grade iron ores are gradually depleted, titanomagnetite is used as an alternative ore for steel smelting [1,2]. Due to a unique crystal structure, the TiO2 grade in titanomagnetite concentrate (TC) is inevitably increased, which results in problems such as liquidus temperature increase, decrease in the reduction effect of the ore, and viscous smelting slag [3,4,5,6,7,8]. Direct reduction-electric furnace smelting is used in South Africa and New Zealand. For this method, the grade of titanium in TC must be under 1% [10]. CaCO3 is one of the most common substances on earth It is found in rocks such as marble and calcite. X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) analysis were used to study the mechanisms, and thermodynamic calculations provided a clear theoretical basis
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