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Estonian SME BiotaTec (BT) is an R&D company developing new bioleaching routes for different organics containing ores having metal compounds trapped in metallo-organic complexes. The effectiveness of the bioleaching process is raised by 2 factors in BT approach – higher yield of metals and lower energy costs due to generation of methane gas. Two-step technology is being tested also for recycling WEEE and used lubricating oils, various phosphorite rocks, oil shales and black shales i.e. low grade raw materials for what traditional metallurgy is not cost-efficient to use.
SME started the development of technology in 2010 with testing Estonian low-grade ore named Graptolite Argillite (GA), a potential source for U, V, Mo, Ni, Re, etc. Like in many formations of black shales and other ores, metals also in GA are present in 2 forms - as sulphides or in the composition of organo-metallic compounds called metallo-porphyrins (molecules with tetrapyrrole macrocyclic structures substituted with alkyl chains). Although there is an extensive list of bioleaching studies using pure mineral sulphide concentrates, much less is known about the microbial decomposition of organo-metallic complexes. The presence of organic material is believed to be the obstacle of efficient bioleaching of metals from GA. Metallo-porphyrins are considered to be the compounds most resistant to degradation.
In the review of Watling (2015) it is admitted that there are considerable data on ore geochemistry and ore genesis on black schists and shales, but problems of extraction metals from organometallic complexes exist.
The BiotaTec search for the most effective microbial consortium and best conditions for the degradation of the metallo-organic complexes has resulted with a determination of a group of heterotrophic microorganisms and methanogens, that work in anaerobic conditions at neutral pH. Majority of bioleaching experiments worldwide have been performed in aerobic environment, where some metabolites accumulating in a culture medium may inhibit further degradation of organic matter, including metal leaching. However, anaerobic biodegradation processes occur slowly in comparison with aerobic growth. Importantly, the microbial community selected in BT studies contains several facultative anaerobes able to grow under aerobic conditions.
Based on numerous tests with various cultivation media, BT has selected, characterized (via DNA sequencing) and deposited a mixture of hetherotrophic neutrophils and methanogenic archaea under CELMS No EEUT ARGCON5 - a consortium of micro-organisms that degrades the organic complex and also leaches some metal compounds in the same anaerobic process.
Based on findings made so far BiotaTec has drafted a new possible route for a low-grade ore /end of life products bioleaching process. A technological solution is offered for situations where extracting valuable metal compounds from organo-metallic complexes has been either impossible or not cost-efficient and environmentally friendly due to large quantities of strong acids needed to break the complex.
SME was created in 2007 as a spin-off from Tallinn University of Technology. For 9 years, the company performed metagenomic testing of environmental samples as ISO17025 accredited testing lab and fulfilled various R&D projects for industries and governmental institutions.
BiotaTec is the only institution in Estonia since regaining the independence in 1991 that has won a public procurement of R&D project investigating the bioleaching of GA. In 2016 by the order of Ministry of Environment of Estonia the company completed a preliminary feasibility assessment of bioleaching the argillite.
Scientists from different faculties of Estonian Universities are outsourced by BiotaTec for specific sub-topics of the complex R&D.


Raw materials Innovation actions (b) Processing of lower grade and/or complex primary and/or secondary raw materials in the most sustainable ways (IA)
Recovery of raw materials from End-of-life products (ERA-MIN Joint Call 2)


Dipl. Eng Sirli Sipp Kulli
BiotaTec Ltd
Mäealuse 4
12618 Tallinn
Phone: +37255530790
Organisation: Industrial SME

Responsible NCP

Ülle Napa
Estonian Research Council