The secondary encapsulation of gold and silver by silicates and Fe-oxide during the roasting oxidation of refractory gold concentrate significantly influence the gold and silver leaching efficiency. In this study, a pretreatment method of refractory gold concentrate calcine using ammonium bifluoride and sulfuric acid solution is proposed. The effects of the NH₄HF₂ and H₂SO₄ concentration, pretreatment temperature, and time on the leaching efficiency of gold and silver were investigated in detail. The optimum conditions were determined to be NH₄HF₂ concentration of 1.5 mol/L, H₂SO₄ concentration of 2 mol/L, pretreatment temperature of 40°C, and duration of 90 min. The leaching efficiency of gold and silver reached 97.6 % and 94.8 %, respectively. The pretreatment process of refractory gold concentrate calcine can be expressed with Johnson-Mehl-Avrami (JMA) equation and depends on the diffusion. The pretreated residue was mainly composed of silicates and Fe-oxide minerals. The gold and silver can be exposed to the ore surface by NH₄HF₂ pretreatment, which helps to improve its cyanide leaching efficiency.

难熔金精矿焙烧氧化过程中硅酸盐和氧化铁对金银的二次包封显着影响金银浸出效率。本研究提出了一种采用氟化氢铵和硫酸溶液预处理难熔金精矿煅烧的方法。详细研究了NH ₄ HF ₂和H ₂ SO ₄浓度、预处理温度和时间对金银浸出率的影响。确定最佳条件为NH ₄ HF ₂浓度为1.5 mol/L，H ₂ SO ₄浓度为 2 mol/L，预处理温度为 40°C，持续时间为 90 分钟。金、银的浸出率分别达到97.6%和94.8%。难熔金精矿煅烧的预处理过程可以用Johnson-Mehl-Avrami（JMA）方程表示，并且取决于扩散。预处理后的残渣主要由硅酸盐和氧化铁矿物组成。_{NH 4} HF ₂预处理可使金、银暴露于矿石表面，有助于提高其氰化物浸出效率。