1. Mining Waste Reduction Methods
Veiko Karu, Ingo Valgma, Tiit Rahe
Tallinn University of Technology (Estonia)
veiko.karu@ttu.ee, ingo.valgma@ttu.ee, tiit.rahe@ttu.ee
Abstract — Mining waste reduction methods include all
mining processes beginning from resource distribution until
final yield in the plant. For comparing and testing possibilities of
mine waste reduction cooperation project has been set up aiming
to create a transnational network with regional networks. The
activities carried out on the regional and transnational level will
secure better access to knowledge, state-of-the-art technologies
and good practice to Small and Medium Enterprises active in
the mineral waste management & prevention sector. The project
addresses all the waste management challenges and
opportunities, which face the Baltic Sea Region mining industry,
which should be understood as extending to all forms of
extraction of natural non-renewable resources. The project
activities will be facilitated by the commitment to participate by
an additional 15 associated organizations representing mining
industry stakeholder associations and/or national government
bodies.
I. INTRODUCTION
Knowledge and technology transfer to Small and Medium
Enterprises (hereinafter SME) in the Baltic Sea Region
(hereinafter
BSR)
will
demonstrate
promising
technologies/processes that have already been substantially
researched and tested, but not demonstrated in situ. These
demonstration investments will represent added value for the
BSR as a whole. Follow-up activities will ensure that these
examples of good practice are transferable or at least
adaptable to multiple regions represented in the BSR [1].
The regions participating in follow-up activities to the
given investment will specify the waste streams they want
tested. Based on this feedback, the investing organization will
identify key process parameters essential for obtaining a
product with the required properties for selected types of
waste.
Each of the investments proposed is justified by the current
state of waste management and the commonalities shared by
different regions in the BSR.
structural concrete). Therefore construction of a mobile unit
for sieving, crushing, screening of material has been chosen.
The mobile unit can be transported to different locations
where waste dumps are situated. Alternatives to Portland
cement and other standard aggregates are being sought.
Oil shale utilisation losses reach 70% in some cases
[3][5][6]. These are closely related to legislation, backfilling
and waste rock usage. Much smaller sections include
production of oil, electricity and chemicals in which most of
the research and development is performed today. Current
urgent topics for investigating, testing and developing of oil
shale mining related questions are backfilling, mechanical
extracting of shale, fine separation, selective separation and
optimised drilling and blasting.
Mining related waste is mainly solid waste from separation
and processing, operating solid waste from overburden
removal and drifting, liquid waste from dewatering,
processing and washing processes. Origin of mining waste is
separation waste form HMS, processing waste, crushing and
screening waste [2][4][7].
The main usage of solid mining waste is filling material,
construction material, cementing material [12]. The principal
direction of developing mining technology is filling the
mined area. This provides control over majority of
environmental effects. Filling the workings decreases the loss
of resources and land subsidence, and at the same time
provides usage for stockpiling. Filling the spoils of surface
mine decreases dewatering; harmless waste can be used for
filling surface mines and in this manner offer new building
land [8] [9][10][11] [13][14][15].
A. Waste Rock Dumps Are Located in Huge Amounts
Near the Area of Abandoned Mines
As an example, the total volume of waste rock from oil
shale mining is more than 76 million m3 and covers about
790 ha in Estonia itself. Similar problems are found in
Sweden and Finland. In Sweden there are several old deposits
from oil-shale mining, the largest one (Kvarntorp) contains
some 40 million m3 of crushed processed black shales and
contains several metals of potential value. The Estonian
solution will help bring down the scale of unused waste rock
by offering up a technological process for the production of
aggregate for structural concrete and for other types of
construction material.
II. UNIT ESTONIA: WASTE TO PRODUCT MOBILE UNIT
Investment objective: Production of material from mining
wastes appropriate for construction industries (aggregate for
Fig. 1. Crushing bucket and wheel loader.
Tests with dry crushing have been carried out on several
sites with oil shale, run of mine (Fig. 2) and waste rock in
addition to sand and gravel crushing. The material has been
evaluated and initial results received.
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2. which hasn't been done before. Transnational relevance as
metal recovery from waste is not usual in BSR.
Fig. 2 Oil shale selective crushing test results with ALLU crushing buckets.
B. Mining Waste Very Often Contains Metal Elements,
Including a Mix of Rare Earth Metals
They are as follows: Zn, Pb, Cu, Cd, As, Ag, Au, Ni and
Co, which are both valuable and pose an environmental threat
when dispersed in nature. In Sweden 61 800 000 tonnes of
mining waste was produced in 2006, which accounts for 51%
of all waste produced in this country.
Of this almost nothing was reused or recycled and in the
few cases when mining waste was reused. There are no
statistics for the amounts of historical mining waste produced
since medieval times in the more than 8500 deposits that have
been in production in Sweden. The level of recovering or
reuse of waste from metal mining is low, especially in copper
mine located in Lower Silesia, where all amount of waste is
storied on the tailing dump, which is the biggest in Europe.
Wastes from metal mining (some valuable and other toxic)
which poses a dual challenge for the waste management
community - how to recover metals elements, which are used
in a variety of advanced and emerging technologies, AND
how to contain compounds with toxic properties (or remove
them for separate storage).
The challenge is made even greater by environmental
regulations, both on the national level and on the EU-level.
The Sweden pilot investment will address both of these issues,
by introducing a novel process for recovery of rare earth
metals and in parallel a range of remediation methods using
alkaline waste materials will be developed. In this investment,
the emphasis will be on waste from the extractive industry
(waste rock & tailings) and the metal processing industry
(slags etc.). In the Finnish pilot investment, the emphasis will
be on a different mix of waste (magnesite, calcite-bearing
waste material), and the product-like output would be used as
an adsorbent in the waste water purification processes.
Fig. 3. Mobile unit for recovery of metals from various categories of mining
waste and metal-rich process residues: 1) a combination of a jaw crusher and
another type of mill crushing the waste down to roughly 0.1 mm; 2) a
leaching apparatus designed to leach (using manipulated water solutions)
solid waste using high pressure and temperature; 3) a mixer-settler unit for
recovery of metals by using liquid/liquid extraction (photo by Bert Allard).
C. Total Amount Mining and Mineral Processing
Wastes Stored on the Waste Facilities
Most of it has ended up as tailings in tailings ponds or
earthen structures. A similar situation can be observed in
Germany, Finland, and Estonia. The Polish pilot investment
will develop the aggregate, which will rely on the hard coal
treatment and possibly other wastes streams. These waste
streams will be different than those proposed in the Estonian
investment, which will rely on mining waste mix based on oil
shale waste rock, and will include oil shale combustion byproducts such as ash. The aggregate developed will be
beneficial because they reflect the different waste streams
which are prevalent in the BSR.
IV. UNIT FINLAND: MOBILE RESEARCH ENVIRONMENT
SUPPORTING MINING AND PROCESS WASTE RESEARCH
Objective: to test the recycling of mine waste with view to
future commercial potential. A mobile module will be
constructed, transportable to site where the waste is processed.
The main element is dry grinding and classification of the
material according to the grain size. Simultaneous analysis is
required to control the promotion of classification procedure.
Novelty: produced material combined with other components
can be used as an adsorbent in waste water purification.
III. UNIT SWEDEN: POST MINING VALUABLE METAL
RECOVERY
Pilot plant to develop business opportunities for SMEs by
extracting valuable and/or hazardous metals etc. from mining
and metal processing waste. Pilot unit involve: (1) Crushing
and milling (2) Leaching (3) Recovery of elements from
solution. Possible innovation related to treating old tailings
and slags through leaching with different aqueous media,
Fig. 4. XRF MiniPal4 for chemical characterization of the samples (photo by
Hanna Repo).
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3. V. UNIT POLAND: NOVEL ARTIFICIAL AGGREGATE FOR
CONSTRUCTION INDUSTRY
Investment objective: to prepare an aggregate for wastes
from mineral treatment plant and useful minerals enrichment
plant. Aggregate from fine-grained wastes will be produced
using agglomeration process. Installation will include
screamer, crusher, mixer, and measurement devices (to
control physical & chemical properties). The installation will
allow to test various coal processing wastes, and other
mineral processing wastes (sandstone/mudstone/claystone
mixed wastes from gravity washers in heavy liquids). The
product: crushed aggregates mix 4(5)-31.5 mm, useful in
mining, building and road construction.
Fig. 5. Polish pilot installation (scheme by Krzysztof Galos).
ACKNOWLEDGMENT
The research is supported by project MIN-NOVATION –
http://www.min-novation.eu; ETF8123 “Backfilling and
waste management in Estonian oil shale industry” –
http://mi.ttu.ee/ETF8123 and AR12007 “Sustainable and
environmentally acceptable Oil shale mining” –
http://mi.ttu.ee/etp. This research work has been supported by
European Social Fund (project “Doctoral School of Energy
and Geotechnology II”), interdisciplinary research group
“Sustainable mining” – http://egdk.ttu.ee
Part-financed by the European Union (European Regional
Development Fund and European Neighbourhood and
Partnership Instrument)
Scientific work financed from science funds in 2011-2013
allocated for co-financing implement international project.
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