ABSTRACT Some materials when exposed to various conditions can exhibit a rise in temperature without requiring an external heat source. Generally referred to as pyrophoric or self-heating substances, they challenge the safety of materials handling, storage and transportation. Reliably assessing the self-heating potential of materials is thus essential. Over the years several test protocols have been developed. A widely accepted method is that recommended by the United Nations (UN) to certify the safety of shipping pyrophoric goods. Our test work on sulphide materials has shown that the UN test can give false negatives if the sample oxidation history is not considered. Depending on the degree of oxidation (‘weathering’), the same sulphide material can exhibit self-heating ranging from safe to hazardous. To make the UN test, and other single-stage self-heating procedures, more reliable in assessing self-heating potential of sulphide materials, it is recommended that a weathering step be incorporated in the test protocol. Our test work on two sulphide samples, an ore and a concentrate, demonstrates the impact of incorporating a weathering stage in the test protocol.

中文翻译：

---

联合国硫化物自热试验的审查

摘要 一些材料在暴露于各种条件下时，无需外部热源即可表现出温度升高。它们通常被称为自热物质或自热物质，它们对材料处理、储存和运输的安全提出了挑战。因此，可靠地评估材料的自热潜力至关重要。多年来，已经开发了多种测试协议。一种被广泛接受的方法是联合国 (UN) 推荐的用于证明运输自燃货物的安全性的方法。我们对硫化物材料的测试工作表明，如果不考虑样品氧化历史，联合国测试可能会给出假阴性结果。根据氧化程度（“风化”），相同的硫化物材料可以表现出从安全到危险的自热。为了进行联合国测试，和其他单级自热程序，在评估硫化物材料的自热潜力时更可靠，建议在测试协议中加入老化步骤。我们对两个硫化物样品（矿石和精矿）的测试工作证明了在测试协议中加入风化阶段的影响。