Metallurgical processes demand large quantities of water. However, in many locations, water is becoming scarce and process water recycling is needed. Closing water loops can be challenging due to build-up of flotation chemicals, metal ions and microorganisms in the recycled water affecting the flotation performance. Here, we have characterized the microbial communities over a 2-month period in different locations of the multi-metal Kevitsa mine in Northern Finland, by microbiome sequencing, enumeration of bacteria, archaea and fungi by qPCR, and cultivation. The microbial communities showed high diversity, but were dominated by Alpha- and Gammaproteobacteria. In addition, various fungal taxa were detected, whereas the archaeal taxa were only sparsely detected from the sequence data. The number of bacterial 16S rRNA gene copies in Process water and Ni thickener overflow varied between 0.5–3.3 × 10⁵ mL⁻¹, whereas the Flotation tailings showed two orders of magnitude lower amounts. Fungi were present at 3.0 × 10²–8.1 × 10⁴ 5.8S rRNA gene copies mL⁻¹ in all samples, while the number of archaea fluctuated between 8.8 × 10¹–3.2 × 10⁵ 16S rRNA gene copies mL⁻¹. The number of all microbial groups were generally lower in September than in August. When tested on 8 different cultivation media, the microorganisms generally responded positively to organic carbon, and were also shown to oxidize thiosulfate, which may indicate that build-up of organic flotation chemicals and sulfur species from the ore may cause the microbial numbers to increase. This study is part of the H2020 ITERAMS project (Grant agreement# 730480), which strives to improve the recycling of water and minimize the environmental impact of mines.

冶金过程需要大量的水。但是，在许多地方，水变得越来越稀缺，需要循环使用生产用水。由于循环水中的浮选化学品，金属离子和微生物的积累会影响浮选性能，因此关闭水循环可能具有挑战性。在这里，我们通过微生物组测序，qPCR计数细菌，古细菌和真菌以及进行培养，对芬兰北部多金属Kevitsa矿在不同位置的两个月内的微生物群落进行了表征。微生物群落显示出高度的多样性，但主要由α-和γ-变形杆菌组成。另外，检测到各种真菌类群，而仅从序列数据中稀疏地检测到古细菌类群。⁵  mL ^-1，而浮选尾矿则显示出低两个数量级。在所有样品中，真菌的存在率为3.0×10 ² –8.1×10 ⁴ 5.8S rRNA基因拷贝mL ^-1，而古细菌的数量在8.8×10 ¹ –3.2×10 ⁵ 16S rRNA基因拷贝mL ^-1之间波动。9月所有微生物组的数量普遍低于8月。当在8种不同的培养基上进行测试时，微生物通常对有机碳有积极的反应，并且还显示出氧化硫代硫酸盐的趋势，这可能表明矿石中有机浮选化学物质和硫物种的积累可能导致微生物数量增加。这项研究是H2020 ITERAMS项目（授予协议号730480）的一部分，该项目致力于改善水的循环利用并最大程度地降低矿山对环境的影响。