| 1. |
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Bäckström, Mattias, 1974-, et al.
(författare)
-
Flooding of oxidized waste rock amended with alkaline by-products
- 2010
-
Ingår i: 34<sup>th</sup> British Columbia Mine Reclamation & 35<sup>th</sup> CLRA/ACRSD National Conference. ; , s. 10 pages-
-
Konferensbidrag (refereegranskat)abstract
- Leaching of trace elements (Cd, Cu, Pb and Zn) from oxidized waste rock amended with different alkaline by-products was studied during flooding. It has been argued that water covers for oxidized waste would significantly increase leaching through reductive dissolution of the pre-formed hydrous ferric oxides and the associated trace elements. After approximately three weeks pH in the reference had reached 2.5 and 3.3 in the pore and overlying water, respectively. This can be compared with pH from 6.1 (water works granules) to above 10 (lime kiln dust) in the amended systems. It is clear that the carbonate dominated alkaline by-products have lower pH than the oxide/hydroxide based by-products. However, the systems amended with carbonate based by-products have significantly higher alkalinity. Cadmium, Cu, Pb and Zn concentrations within the waste decreased with at least 99% compared to the reference. In most systems the surface waters can even be used as drinking water. Cadmium, copper and zinc concentrations are clearly related to pH with decreasing concentrations with increasing pH. Lead concentrations, on the other hand, decrease to pH 8, where the concentrations start to increase slightly again due to the formation of soluble Pb(OH)₃⁻ and Pb(OH)₄²⁻ species. The results indicate that flooding of oxidized waste rock amended with alkaline by-products can be used as a successful remediation technique.
|
|
| 5. |
- Bäckström, Mattias, 1974-, et al.
(författare)
-
Fly ash injection into weathered mine waste
- 2013
-
Ingår i: Annual International Mine Water Association Conference. - Colorado, USA : IMWA. - 9780615793856 ; , s. 513-519
-
Konferensbidrag (refereegranskat)abstract
- By adding alkaline ashes through injection to weathered mine waste pH increased approximately 3 units, trace element was immobilized and flow rate decreased due to formation of hard pans. Reduction in trace element concentrations was around 96.9-99.6 % for copper, 94.7-99.7 % for zinc and 22.9-99.8 % for cadmium. For lead the best reduction was 97.3 % and the worst -393 % (increase). MSWI ashes performed worst with low buffering capacity and increase in vanadium and molybdenum concentrations.
|
|
| 6. |
- Bäckström, Mattias, 1974-, et al.
(författare)
-
Mining Waste as an Exploration Tool and Secondary Resource
- 2017
-
Ingår i: Mine Water & Circular Economy. - Lappeenranta, Finland : Lappeenranta University of Technology. - 9789523350656 ; , s. 964-971
-
Konferensbidrag (refereegranskat)abstract
- There is today no overall information about how much mining waste there is in Sweden and what it contains. This project focused on samples from waste rock, tailings and slag from the historical mining region Bergslagen, Sweden. Modern dissolution and analytical methods were used in order to determine approximately 50 elements in the samples. Modern analytical data for the historical mining waste is useful as an exploration tool and can provide information about remaining or new resources underground. Results show that there is a potential for recovery of critical elements from mining waste as well as dealing with environmental problems.
|
|
| 7. |
- Bäckström, Mattias, 1974-, et al.
(författare)
-
Mixing of acid rock drainage with alkaline ash leachates : fate and immobilisation of trace elements
- 2011
-
Ingår i: Water, Air and Soil Pollution. - : Springer. - 0049-6979 .- 1573-2932. ; 222:1-4, s. 377-389
-
Tidskriftsartikel (refereegranskat)abstract
- Acid rock drainage (ARD) from mine waste dumps often contains ferrous iron, sulphate and high concentrations of trace elements detrimental to the environment. Future costs will be enormous if the problem is not treated today. Simple, low maintenance, cost-effective methods for remediation of historical mine sites are therefore desired. In this study several mine waters were mixed with an alkaline ash leachtes in order to study the fate of the trace elements from both the mine waters (Cd, Cu, Pb, Zn, Ni and Co) and the ash leachates (Cr and Mo). It was found that the addition of ash water will precipitate hydrous ferric oxides (HFO) and hydrous aluminium oxides (HAO) and thereby inducing trace element sorption and co precipitation. It is also clear that the composition of the formed HFO/HAO mix determines the efficiency of the sorption for different trace elements. It is apparent that the amount of precipitating iron will determine the effectiveness of the removal of the trace elements. Sorption occurred much earlier (often one pH unit or more) in the system with high iron concentrations compared to the systems with lower iron concentrations. Removal of cadmium and zinc is difficult below pH 8 if the amount of precipitates is low. Using ash for generation of alkaline water may be a problem with regards to chromium and molybdenum. It is, however, possible to avoid problems with molybdenum by keeping the final pH around 7 and chromium(VI) from the ash water will be reduced into chromium(III) and precipitated as the hydroxide in the presence of iron(II) from the mine waters.The results imply that it is possible to also use fly ashes in alkaline leach beds in order to neutralize ARD followed by precipitation and sorption of trace elements.
|
|
| 8. |
- Bäckström, Mattias, 1974-, et al.
(författare)
-
Permanent under water storing of weathered mine waste after removal of fine fraction and addition of ash
- 2014
-
Ingår i: An Interdisciplinary Response to Mine Water Challenges. - Xuzhou : China University of Mining and Technology Press. - 9787564624378 ; , s. 711-714
-
Konferensbidrag (refereegranskat)abstract
- Weathered sulphidic mine waste is a major environmental problem. An experiment was performed in order to study water covers for oxidized mine waste. In two experiments oxidized mine waste were covered with water, in one experiment the fine fraction was removed and in one experiment alkaline ash was also added prior to water covering. It was found that removal of the fine fraction decreased pH and increased trace element concentrations. Water covering of the mine waste with and without ash decreased trace element concentrations indicating that co disposing oxidized sulphidic mine waste and ash under water might be a promising remediation method.
|
|
| 9. |
- Bäckström, Mattias, 1974-, et al.
(författare)
-
Properties of alkaline materials for injection into weathered mine waste piles : methods and initial pilot trials
- 2011
-
Ingår i: Mine water. - Aachen : RWTH. - 9783000355431 ; , s. 265-269
-
Konferensbidrag (refereegranskat)abstract
- Several alkaline materials were studied with regards to their ability to form stable suspensions withwater. Gravitational injection of alkaline materials were performed into weathered mine waste in two differentpilot scales (25 L and 1 000 L). When water was added after injection lime mud (LM) was flushed out whilelime kiln dust (LKD) and green liqour (GLD) remained within the mine waste. Deconstruction of the pilot sys-tems showed that both materials had penetrated the voids present. LKD and GLD increased pH significantlyand reduced trace metal concentratios. It is concluded that both LKD and GLD are suitable for stabilizing acidgenerating mine waste.
|
|
| 10. |
- Bäckström, Mattias, 1974-, et al.
(författare)
-
Stabilization of acid generating waste rock with fly ash : Immobilization of arsenic under alkaline conditions
- 2010
-
Ingår i: Mine water & innovative thinking. - ovaScotia, Canada : Cape Breton University Press. - 9781897009475 ; , s. 555-558
-
Konferensbidrag (refereegranskat)abstract
- A fly ash was used to increase pH and decrease arsenic leaching from an acidic mine waste.Both the amended system as well as the control system was leached with ultra pure water. pH in thecontrol increased from 1.7 to 2.7 at the end of the experiment while the pH in the amended systemdecreased from 12.6 to 11.5. compared to the control the initial concentrations of arsenic decreasedwith almost three orders of magnitude in the amended systems. A combination of co precipita-tion with iron and calcium arsenate precipitation were identified as the major arsenic immobi-lization mechanisms.
|
|
