oru.sePublications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Leaching of lime kiln dust and LD-slag with ARD in a sequential batch experiment
Örebro University, School of Science and Technology. (Människa-Teknik-Miljö)
Örebro University, School of Science and Technology. (Människa-Teknik-Miljö)ORCID iD: 0000-0002-2674-4994
Örebro University, School of Science and Technology. (Människa-Teknik-Miljö)
Örebro University, School of Science and Technology. (Människa-Teknik-Miljö)ORCID iD: 0000-0002-2104-4593
2010 (English)Manuscript (preprint) (Other academic)
Abstract [en]

Treatment of ARD in a reactive barrier or an alkaline filter prior to release to the recipient is a desired and often suggested alternative. Alkaline candidate materials for the purpose that are cheap are by-products such as fly ash, lime kiln dust and different steel slags. An experiment was carried out where two highly alkaline by-products (LD slag and lime kiln dust) were exposed to a real ARD in sequential batch design.

It was found that the buffering capacity was high enough in both materials in order to neutralize the added ARD even if large portions of the total buffering capacity was washed out during the experiment. Washing out of alkalinity is a greater problem for oxide/hydroxide materials than it is for carbonate dominating materials. Calculations indicated that the buffering capacity in the LKD would last at least until L/S 3 000 while it would last approximately until L/S 1 000 for LD slag. Lack of buffering capacity is thus not the major problem with the materials, but rather the lack of capacity for trace element immobilization. Including sorption onto HFO and HAO and precipitation of different hydroxides and carbonates the already immobilized trace elements from the added ARD started to be remobilized around pH 8. Below pH 8 concentrations increased rapidly due mainly to desorption and was soon found to be higher than in the added ARD.

Some of the divalent elements (Mg and Mn) were also found to be controlled by their hydroxides at high pH and at circumneutral pH by their carbonates. This results in higher concentrations at lower pH (below 10) since the carbonates are more soluble than the hydroxides.

It is important to characterize the used alkaline by-products at the expected chemical conditions in order to be able to assess potential trace element leaching (most likely anionic elements such as vanadium and chromium).

Place, publisher, year, edition, pages
2010.
Keywords [en]
HFO, HAO, pH, vanadium, trace elements
National Category
Environmental Sciences
Research subject
Enviromental Science
Identifiers
URN: urn:nbn:se:oru:diva-12011OAI: oai:DiVA.org:oru-12011DiVA, id: diva2:354858
Available from: 2010-10-05 Created: 2010-10-05 Last updated: 2017-10-17Bibliographically approved
In thesis
1. Alkaline by-products as amendments for remediation of historic mine sites
Open this publication in new window or tab >>Alkaline by-products as amendments for remediation of historic mine sites
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Mining has been and still is an important industry in Sweden, it has strongly contributed to the standard of living we have today. Extraction of ore began in the 12th century, but did not come about frequently until the 16th century, which is often seen as the starting age for ore processing and metal extraction. Leaching from sulphidic mine waste deposits is a serious environmental issue. When some of the sulphide minerals come into contact with oxygen they produce acid. Low pH in the waste then promotes leaching of primarily iron and cationic trace elements like copper, zinc and lead and hence affects the surrounding environment by bringing these metals in solution. Mine waste produced today is therefore immediately treated to prevent further oxidation and metal leaching. Cost-effective solutions for the historic mine waste are though still needed, especially as legal responsibilities for the historic waste are in many cases unclear. The historic mine waste is often highly weathered due to long-time exposure to oxygen and water, and also contains higher metal concentrations than modern waste. Also, consideration has to be taken to cultural and historical interests. Covering of the waste is commonly applied for acid rock drainage (ARD) control. By minimizing the oxygen supply, the waste is controlled from further oxidation. Covers can consist of layers of highly impermeable materials or water. Reactive materials (pH-increasing or reducing) can be used as covers or amendments. ARD can also be controlled and treated with reactive barriers and filters. Generally, when neutralizing materials are used for improvement of mine waste or ARD, pure materials such as lime is used. A lot of alkaline by-products in Sweden are deposited as waste and the increasing amount of wastes is also a main environmental problem. The use of alkaline by-products to amend acidic mine waste or ARD therefore both saves natural resources and reduces costs. In the present study, various alkaline by-products have been used in laboratory- and field-scale experiments, either as amendments to historic mine waste or for treatment of ARD. They include: lime mud, green liquor dregs, fly ash, steel slag, lime kiln dust and water works granules. Differences between the alkaline source (carbonate or hydroxide) were shown to be a crucial factor, especially in ARD treatment. Slow dissolution rates for carbonate materials in combination with high iron concentrations resulted in iron precipitation and coating of neutralizing carbonate surfaces. Hydroxide materials was hence found to be superior to carbonate materials in ARD applications and also as solid amendments to oxidized mine waste, in the case where the alkaline material was added as discrete layers. The latter enabled formation of so called hard pans, which work as flow rate reducers and allowing longer contact time with the neutralizing source. Though, when alkaline materials were homogeneously mixed with oxidized mine waste, carbonate materials were able to generate a higher pH and alkalinity, followed by lower trace metal concentrations. Key Words: Oxidized mine waste, lime mud, green liquor dregs, fly ash, lime kiln dust, steel slag, water works granules

Abstract [sv]

Gruvindustrin är sedan länge av stor ekonomisk vikt för Sverige och gruvorna harhaft stor betydelse för vår välfärd även historiskt sett. Av den malm som bryts ärca en fjärdedel järnmalm och tre fjärdedelar sulfidmalm. Vid malmbrytning bildasstora mängder avfall, vilket tas om hand av verksamhetsutövaren som bäransvaret för miljöpåverkan. Läckage från deponier för sulfidhaltigt material kange upphov till omfattande påverkan på den omgivande miljön genom försurningoch spridning av (tung)metaller. För att förhindra försurning täcks vanligtvisavfallet med jord eller vatten. Detta gör man för att förhindra sulfidoxidationsom kan leda till att surt och metallrikt lakvatten transporteras ut från en deponi.I Bergslagen finns ett stort antal historiska gruvområden i behov av åtgärd, dåde kan utgöra ett hot mot både människors hälsa och miljö. Uppskattningsvisfinns gruvavfallsmaterial i storleksordningen varp 3 miljoner m3, sand 14miljoner m3 respektive slagg 1,5 miljoner m3 som är aktuellt för efterbehandling iDalarnas, Västmanlands och Örebros län. Kostnaderna för efterbehandling avdessa områden beräknas uppgå till mellan två och tre miljarder svenska kronor.Äldre avfall skiljer sig i regel från nyproducerat avfall med avseende på avfalletsmetallinnehåll och vittringsgrad samt problem med ansvarsfrågor och frågorrörande kulturhistoriska värden.Vid historisk gruvbrytning (före 1900) fanns inte lika effektiva sorteringsmetoderoch anrikningsprocesser som idag. Således innehåller historisktgruvavfall generellt sett högre metallhalter. Avfall från historiskt gruvavfall harockså varit exponerat för luftens syre, nederbörd och erosion under lång tid.Detta har medfört att en stor andel av det järn som finns närvarande är trevärt(dess oxiderade form), vilket gör att oxidation kan fortgå även om man täckeravfallet.Alkaliska restprodukter från fyra olika branscher, representerade av kalkindustrin,stålindustrin, pappersmassaindustrin samt energiproducentindustrin,har under fyra år studerats för att bestämma deras lämplighet för olika typer avefterbehandlingar av vittrat, surt gruvavfall. Försök har gjorts i labskala, samtstörre pilotskaleförsök, hädanefter benämnda mesoskala. Laboratorie-försökenhar syftat till att utreda neutraliseringspotential, lämpliga inblandningsproportioneroch eventuella metalläckage från de alkaliska materialen. Försökensom gjorts i mesoskala har dels syftat till att studera effekter av att blanda vittrat,sulfidrikt gruvavfall med alkaliska material, så kallade stabiliseringsförsök.Därutöver har försök gjorts med syfte att rena lakvatten från gruvavfall. I detsenare försöket har de alkaliska materialen placerats i 0,4 m3-behållare och surt,metallrikt lakvatten har låtits passera, med pH-ökning och metallfastläggningsom följd.Utifrån resultaten kan vissa av materialen anses ha god förmåga attneutralisera gruvavfallet eller lakvatten från gruvavfallet samt minska utläckageav tungmetaller såsom koppar, zink, kadmium och bly. För dessa materialplaneras i nuläget för fortsatta försök i fullskala. För de material som intefungerat tillfredställande nog för att fortsätta i fullskala kommer ytterligarestudier samt modifikationer av metodiken att utföras, t ex kommer merreducerande förhållanden att försöka uppnås genom att försöksbehållarna täcksmed syreförbrukande material, t ex rötslam.

Place, publisher, year, edition, pages
Örebro: Örebro universitet, 2010. p. 108
Series
Örebro Studies in Environmental Science, ISSN 1650-6278 ; 15
Keywords
Oxidized mine waste, lime mud, green liquor dregs, fly ash, lime kiln dust, steel slag, water works granules, Oxiderat gruvavfall, mesakalk, grönlut, flygaska, filterkalk, stålslagg, vattenverksgranuler
National Category
Natural Sciences Environmental Sciences
Research subject
Enviromental Science
Identifiers
urn:nbn:se:oru:diva-11659 (URN)978-91-7668-750-5 (ISBN)
Public defence
2010-10-08, Örebro universitet, Hörsal Bio, Fakultetsgatan 1, Örebro, 10:15 (English)
Opponent
Supervisors
Projects
Forskningsprojekt: Efterbehandling av gamla gruvavfallsdeponier med hjälp av alkaliska restprodukter. I samarbete med EU-projektet Bergskraft Bergslagen
Available from: 2010-08-30 Created: 2010-08-30 Last updated: 2017-10-18Bibliographically approved

Open Access in DiVA

No full text in DiVA

Authority records BETA

Sartz, LottaBäckström, MattiasKarlsson, StefanAllard, Bert

Search in DiVA

By author/editor
Sartz, LottaBäckström, MattiasKarlsson, StefanAllard, Bert
By organisation
School of Science and Technology
Environmental Sciences

Search outside of DiVA

GoogleGoogle Scholar

urn-nbn

Altmetric score

urn-nbn
Total: 375 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf