This slide is to show the material is approved by the Department of Environmental Protection in Pennsylvania for several usesCOA = Consent Order and AgreementReally need the other approvals??
High-quality, consistent materialFar superior to calcareous materials such as limestoneNote: If other slag materials are used in the future the fineness spec will likely need to be changed
The idea to blend with coal refuse was birthed in 2008, with some third-party column testing performed2011-2012 in-house column testing showed significant reduction in metals when blends were used2012-2013 third-party column testing performed to further validate results, with each final result the average of three columns. A total of 10 treatments were performed, totaling 30 columns.Blending coal refuse and Harsco’s calcium/magnesium silicate material in the correct proportions can completely neutralize coal refuse, and eliminate metal discharges
Refuse is from the lower Kittanning coal seam, which produces a very reactive coal refuseSPLP extraction fluid #1 is used east of the Mississippi - (pH of 4.2 +/- .05 using 60:40 mixture of sulfuric and nitric acid) Simulated more than 40 inches of rainfall per yearNOTE: Column testing is far more rigorous than field application in refuse piles. With columns, all of the water must pass through the system, whereas a great deal of actual rainfall on a refuse pile is deflected in the form of runoff on the surface, with only a portion penetrating into the refuse pile.
While apparent sulfur content is somewhat low on the coal refuse material that was used, it nonetheless generated a great deal of acidity and metals.
Columns were made from 4” diameter x 4’ length PVC pipe, and held 36 inches of coal refuseBlends were by weight, not volumeAll refuse was screened to -1” due to the column diameter of 4”, and thoroughly blended to ensure consistency of material for each column
Partial view of test columns at Test America’s labSPLP fluid dripped in top, collected in bottom dailyEach day represented one month of rain
Placing alkaline materials beneath and/or on top of coal refuse only slightly elevates pH in this test. Real-world results are much better due to rain deflection.Intermixing Harsco’s calcium/magnesium silicate material coal with refuse, even at relatively modest amounts greatly changes pH
Chart shows a summary of all results (one result is the average of three columns) for iron, aluminum, and manganeseYellow highlights for blends were part per billion non-detects
Column tests were performed for a period of 36 months or three yearsPlacing alkaline materials beneath and/or on top of coal refuse can elevate metals in column testing, however real-world results are far more favorable for this type of treatmentIntermixing Harsco’s calcium/magnesium silicate material with coal refuse, even at relatively modest amounts dramatically reduces metals tested – all three blends are at the bottomAs seen, the very high metal discharges are due to the rigorousness of the column test methodDespite the rigorous nature of the method, the blends show extremely high control of each of the three metals (Fe, Al, Mn)
To better see the differentiation between each application method, we will now look at 6 month charts
Aluminum results are similar, with all three blends showing virtually no dissolved metal
And this is trueagain for manganese
Placing alkaline materials beneath and/or on top of coal refuse can reduce EC depending on the system and amount usedIntermixing Harsco’s calcium/magnesium silicate with coal refuse, even at relatively modest amounts greatly reduces TDS, especially at earlier agesNote: EC is measured in microsiemens per centimeter
TDS - total dissolved solids – are a calculation based on electrical conductivityAs seen, placing alkaline materials beneath and/or on top of coal refuse can reduce TDS depending on the system and amount usedAgain, intermixing Harsco’s calcium/magnesium silicate material with refuse, even at relatively modest amounts greatly reduces TDS, especially at earlier agesNote: A .60 conversion factor was used to convert EC to TDS
Placing alkaline materials beneath and/or on top of coal refuse reduces redox potential to varying degreesIntermixing Harsco’s calcium/magnesium silicate with coal refuse, even at relatively modest amounts greatly reduces redox potential at all agesAdditional information on Redox:Usually referred to as ORP – Oxidation-Reduction PotentialMeasured in millivoltsIndicates the potential of substances like chlorine, bromine, or ozone to oxidize (of which their effectiveness can be increased by lower pH and decreased by higher pH)The same term is also used for non-oxygen “oxidation”-reduction. It is any case in which one material gives up electrons (oxidation), and another material takes electrons (reduction), and is always a balanced equationWe can see examples of oxidation all the time in our daily lives. They occur at different speeds. When we see a piece of iron rusting, or a slice of apple turning brown, we are looking at examples of relatively slow oxidation When we look at a fire, we are witnessing an example of rapid oxidation. Oxidation involves an exchange of electrons between two atoms. The atom that loses an electron in the process is said to be "oxidized." The one that gains an electron is said to be "reduced." In picking up that extra electron, it loses the electrical energy that makes it "hungry" for more electrons. (excerpted from Service Industry News article)
Sulfate concentration drastically reduced at early stages, even when only a relatively small amount of Harsco’s calcium/magnesium silicate material in intermixed
Our material does not contain calcium carbonate due to the extremely high heat it was exposed to in the steel-making process.The silicon to iron ratio is important as we tie up some of the iron preventing it from reacting, reducing the effect of the ironThe Sulfur to iron ratio is important as, depending on the amount of iron, especially in the form of pyrite, all of the sulfur may not be available for acid generation Forms mono-silicicacid and not carbonic acid, a much weaker acid, removing H ions so they are not available for other acid generation
A small percentage of Harsco’s material will neutralize acidity and require minimum air spaceVirtual elimination of the metals of most concern:iron, aluminum and manganeseSignificant improvement of other runoff water propertiesWe will discuss each of the benefits in more detail in a moment, but it is worthwhile highlighting that significant cost savings can be had while reducing or eliminating long-term liability risk and exposure by this sustainable environmental solution
The top image depicts the system currently required by the EPA. It consists of a bottom and top cover of a seamless geomembrane liner, and once complete, encapsulates the entire coal refuse pile. No treatment of the material in the pile is done. When considering that geomembrane materials are guaranteed for only 50 years, this is a temporary solution at best (Band-Aid). A downside to this system is that it completely encapsulates the toxic refuse, and once the geomembrane system deteriorates, which it will, there is potential for a tremendous release of toxic acidic water laden with dissolved metals for many decades.Prior systems (and many piles currently being completed) required an impermeable liner (usually geomembrane due to difficulty of obtaining enough clay and its cost) beneath the pile. This allows rainwater to slowly percolate through the pile, eventually running off and being collected for treatment. Although it will take many, many decades to deplete the acid and metal discharge, this at least would likely lessen the issue that will be eventually associated with the upper system. In these older piles Harsco customers have had excellent success covering and or underlying the pile with Harsco’s calcium/magnesium silicate material which pre-treats some of the water, greatly reducing chemical treatment costs and lowering risk to the environment.
We now have the potential to provide a sustainable systemAn added benefit is that this neutralized refuse pile can covered with Harsco’s patented growing medium, a special blend of coal refuse and Harsco’s Calcium/magnesium silicate material, drastically reducing topsoil requirements and cost, and providing far greater depth for other than just growing grass.
Cost-effective, lower risk, environmentally friendly, new land uses, and sustainable. Repurposing of the land can have a huge impact!
Reduce or eliminate inspectionsLet’s look quickly at how the Harsco Engineered Environmental System impacts a typical coal refuse site.Plant operating costs, which can run into the hundreds of thousands of dollars each year for a given site can be drastically reduced and eventually eliminated, saving even the cost of the plant and equipment once Harsco EES is accepted as an alternative system.Harsco’s EES material is 100% recycled with a proven track record and is harmless to the environment. By eliminating calcium hydroxide, considerable CO2 emissions are reduced from being put into the atmosphere.Not only will the mining company benefit, state money and time can be impacted in a positive way.
With considerably reduced risk, trusts and bonding costs can potentially be significantly reducedOne of the big concerns for mining companies is dealing with liner materials, ongoing failures during installation, and slippages which often happen afterwards. By at least eliminating the top geomembrane layer, costs and system failures will be reduced considerably. Harsco’s patented growing medium using coal refuse and Harsco's calcium/magnesium silicate material can save considerable funds and eliminate the need to truck in large volumes of topsoil. The greatest benefits include reduced risk for state agencies, reduced risk of damaging the environment, and reduced long-term liability for the mining company.
As you can see, Harsco’s Engineered Environmental System provides significant benefits over the only it’s main competitor limestone. Due to limestone’s limitations it cannot provide the results needed for a truly sustainable solution.Control System Changes = elimination of at least one liner, along with the associated material, labor, equipment, and other costs. Also the elimination of problems created by the upper liner (slips, repairs and such).
Harsco Mineral CSA: A Sustainable Solution to Acidic Water from Refuse Piles & Abandoned Mine Sites
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