A novel reductive alkali roasting of chromite ores for carcinogen-free Cr6+-ion extraction of chromium oxide (Cr2O3) - A clean route to chromium product manufacturing!
A novel reductive alkali roasting of chromite ores for carcinogen-free Cr6+-ion extraction of chromium oxide (Cr2O3) - A clean route to chromium product manufacturing!
复制标题
DOI：
10.1016/j.jhazmat.2020.123589
复制
发表时间：
2021-02-05
影响因子：
13.6
通讯作者：
Jha, Animesh
中科院分区：
文献类型：
--
作者：
Escudero-Castejon, Lidia;Taylor, James;Jha, Animesh
通过排除致癌铬酸盐 (Cr6+) 中间体的形成，证明了一种从铬铁矿矿石中提取 Cr2O3 的新型还原反应。我们详细研究了基础高温还原反应：FeCr2O4+Na2CO3+2[Cl=[Fel+Na2Cr2O4+3CO((g)))，它定义了作为 Cr2O3 萃取中间产物的亚铬酸钠 (Na2CrO2) 的形成过程化学。高温还原后，反应产物经磁选、水浸和酸浸，从含硅量低（接近 4 wt%）和高硅含量（>8 wt%）的铬铁矿矿石中分别获得了 81 wt% 和 70 wt% 的纯 Cr2O3。该流程图解释了 Cr2O3、Fe-Cr 合金、Al2O3 和 MgO-Al2O3-硅酸盐的提取、CO2 的再利用以回收 Na2CO3，以及 CO 燃烧产生的能量，以演示从铬铁矿矿石中无 Cr6+ 提取金属和矿物价值。该工艺化学演示了通过使用 0.05-0.5 M 稀溶液浸出，从 NaCrO2 中提取 75-80% 纯 Cr2O3 H2SO4 在受控 pH 条件下。对 Cr2O3 提取后的渗滤液进行详细的化学分析表明，残留浓度接近 150 ppm Cr3+-离子的酸性渗滤液可以就地回收以回用水，以消除大气氧化形成 Cr6+-离子的风险。新的提取路线可能能够通过改造取代当前铬铁矿矿石加工的氧化工艺。
A novel reduction reaction for extracting Cr2O3 from chromite ores is demonstrated by excluding the formation of carcinogenic chromate (Cr6+) intermediates. We have investigated in detail the underpinning hightemperature reduction reaction: FeCr2O4+Na2CO3+2[Cl=[Fel+Na2Cr2O4+3CO((g)), which defines the process chemistry for the formation of sodium chromite (Na2CrO2) as an intermediate product for Cr2O3 extraction. After high-temperature reduction, the magnetic separation, aqueous and acid leaching of reaction products yielded 81 wt% and 70 wt% pure Cr2O3 from low (similar to 4 wt%) and high (>8 wt%) silica-containing chromite ores, respectively. The process diagram explains the extraction of Cr2O3, Fe-Cr alloy, Al2O3, and MgO-Al2O3-silicate, reuse of CO2 for Na2CO3 recovery, and energy generation from CO combustion for demonstrating Cr6+-free extraction of metallic and mineral values from chromite ores.The process chemistry demonstrates the extraction of 75-80 % pure Cr2O3 from NaCrO2 by leaching with 0.05-0.5 M dilute H2SO4 in controlled pH conditions. The detailed chemical analysis of leachates after Cr2O3 extraction shows that the acid leachates with residual concentrations of similar to 150 ppm Cr3+-ions can be recycled in situ for reusing water, for eliminating the risk of Cr6+-ion formation from atmospheric oxidation. The novel extraction route may be able to displace the current oxidative process for chromite ore processing by retrofitting.