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 high-temperature reduction reaction: FeCr₂O₄+Na₂CO₃+2[C]=[Fe]+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 (∼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 ∼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.

通过排除致癌铬酸盐（Cr ⁶⁺）中间体的形成，证明了一种用于从铬铁矿矿石中提取Cr ₂ O ₃的新型还原反应。我们已经详细研究了基础的高温还原反应：FeCr ₂ O ₄ + Na ₂ CO ₃ +2 [C] = [Fe] + Na ₂ Cr ₂ O ₄ + 3CO _（g），它定义了Cr ₂ O ₃中间产物亚铬酸钠（Na ₂ CrO ₂）的形成萃取。高温还原后，通过磁性分离，反应产物的水浸和酸浸，从低（〜4 wt％）和高（> 8 wt％）的含硅铬铁矿中获得81 wt％和70 wt％的纯Cr ₂ O ₃。矿石。该工艺图说明了Cr ₂ O ₃，Fe-Cr合金，Al ₂ O ₃和MgO-Al ₂ O ₃硅酸盐的提取，CO _2的再利用以回收Na ₂ CO ₃以及从CO燃烧产生的能量证明了从铬铁矿矿石中无Cr ⁶⁺提取金属和矿物价值。

工艺化学表明，通过在受控pH条件下用0.05-0.5 M稀H ₂ SO ₄浸出从NaCrO _2中提取75-80％的纯Cr ₂ O ₃。Cr ₂ O ₃萃取后渗滤液的详细化学分析表明，残留浓度约为150 ppm的Cr ^3+-离子的酸性渗滤液可就地循环用于水的再利用，从而消除了从中形成Cr ⁶⁺离子的风险。大气氧化。该新颖的提取路线可能能够通过改型代替目前用于铬铁矿加工的氧化过程。