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Thu May 23, 2019, 08:54 PM

The Fate of Vanadium after the Mount Polley Mine Tailings Spill.

The paper I'll discuss in this brief post is this one: Origin and Fate of Vanadium in the Hazeltine Creek Catchment following the 2014 Mount Polley Mine Tailings Spill in British Columbia, Canada (Karen A. Hudson-Edwards et al, Environ. Sci. Technol2019, 53, 4088−4098)

I'm catching up on some reading, and actually missed or overlooked this issue of EST and came across this disaster, of which I was unaware.

Vanadium is an important alloying element used in steels, particularly high strength steels such as are used in high quality tools and, um, things like wind turbines. It is widely distributed on Earth, and is commonly found in synthetic uranium ores prepared by passing seawater over amidoxime resins, a technology designed to exploit the fact that the ocean contains about 5 billion tons of uranium as a result of the geochemical uranium cycle.

The metal exhibits a plethora of oxidation states, and has been suggested for use in "flow batteries" because batteries are often the subject of fantasies about "storing" so called "green energy" even though there is very little of said popularly imagined but endlessly hyped energy to actually store, this after half a century of wild cheering for it, and even though the 2nd law of thermodynamics irrefutably requires that the storage of energy wastes it, and finally even though betting the planetary atmosphere on massive amounts of mining is almost certainly not a good idea and is most definitely not a pro-environmental policy.

However a problem with vanadium is that in some of its common oxidation states its very toxic.

From the introduction to the paper:

Vanadium(V) is a transition metal that is the 22nd most abundant in the Earth’s crust(1,2) and occurs naturally in four oxidation states [V(II), V(III), V(IV), and V(V)]. Although V is an essential element for humans and animals at low concentrations,(3) the intake of high concentrations of V can be carcinogenic and toxic.(4,5) Generally, V(V) is considered to be the most toxic of the V species because it can inhibit or replace phosphate.(6,7) Vanadium is classed by the United Nations, U.S. Environmental Protection Agency, and Chinese Ministry of Environmental Protection as a priority environmental risk element.(2,8−10) In recognition of the potential toxicity of V, Canada has set a Federal Water Quality Guideline of 120 μg/L for protection of aquatic life in freshwater,(11) and Schiffer and Liber(12) have suggested a more stringent chronic hazardous concentration endangering only 5% of species (HC5) of 50 μg/L for Canadian freshwater organisms.

Humans can be exposed to vanadium mainly through inhalation and ingestion, potentially causing long-term respiratory and digestive problems, respectively.(13) Aqueous vanadate [V(V)] can also be taken up in benthic organisms such as Hyalella azteca(14) and have been shown to cause genotoxic and cytotoxic effects in higher plants.(15) Vanadium can be distributed in water, soil, sediment, and air through the weathering of natural materials and through releases from anthropogenic activities, including the burning of fossil fuels, application of pesticides and phosphate fertilizers, steel, aerospace, and other industries, and mining.(9,16,17) For example, mining activities have led to contamination of waters and soils with V (e.g., 76–208 μg/L in groundwaters and 149–4800 mg/kg in soils of the Panzhihua mining and smelting area in China(18,19)). There is, however, a lack of information about, and understanding of, the geochemical–mineralogical cycling of V in mining-affected environments,(20) but these are required to determine health effects and to develop management and remediation schemes...

The fourth August 2014 failure of the tailings storage facility (TSF) at Mount Polley, British Columbia, Canada, is the second largest by volume on record.(23) Approximately 25 Mm3 of material, comprising 7.3 Mm3 of tailings solids, 10.6 Mm3 of supernatant water, 6.5 Mm3 of interstitial water, and 0.6 Mm3 of tailings dam construction materials were discharged into the Quesnel River Watershed.(23−25) The material flowed north into and plugged Polley Lake and then was diverted southeast into Hazeltine Creek for 9.5 km. A significant proportion of the tailings and interstitial water (18.6 ± 1.4 M m3)(25) and eroded soils and vegetation(26) were deposited into the West Basin of Quesnel Lake (Figure 1). Deposition of tailings (average 1 m thick, but up to 3.5 m thick in the upper part of the area nearest the TSF) also occurred within the Hazeltine Creek catchment up to 100 m from the channel, especially near Polley Lake and Lower Hazeltine Creek.(25)...

In this paper, we focus on V due to its high environmental risk potential(2,8−10) and the relative lack of data on its behavior in mining-affected environments.(20) We aim to understand the geochemical cycling of V in the Hazeltine Creek catchment and its implications for the origin, transport, fate, and potentially toxicity of V in other river systems. The objectives of the study are to determine (1) V concentrations and speciation in stream, inflow, and pore waters using aqueous composition data and PHREEQC modeling, (2) solid-phase V concentrations and speciation in the deposited tailings and secondary Fe oxyhydroxides using electron microprobe, automated mineralogy analysis, and X-ray absorption spectroscopy (XAS) analysis, and (3) the environmental origin, fate, and potential hazard of the deposition of V-bearing tailings in mining-affected catchments following tailings dam failures and remediation. We present, for the first time to the best of our knowledge for natural systems, evidence that dissolution of V-bearing magnetite and titanite may contribute to aqueous V. The results will also inform restoration and management schemes for river systems receiving V from other natural and anthropogenic sources.

The authors determined the concentration of vanadium and a bunch of other elements using ICP-OES, which is not the most sensitive inorganic element analytical tool (ICP-MS) is, but is perfectly acceptable where concentrations are relatively high, and they also utilized, and in some cases an older model ICP-MS, not however an instrument with which I am familiar. Speciation was determined by coupling these detectors to an ion chromatograph.

I don't have time for all the details of this paper, but we can look at the pictures:

The caption:

Figure 1. Location of the study area showing the Hazeltine Creek stream (HC-), inflow sample, pore water (PW-) and tailings, sediment, and Fe oxyhydroxide (POL-) sample sites for materials collected in 2014 and 2015. Labels shown are for those samples discussed in this work; sample locations for the remaining stream, inflow, and pore water samples are shown in ref (37).

The caption:

Figure 2. Spatial profile of the Hazeltine Creek stream and inflow filtered (V-F) and unfiltered (V-T) V concentrations. Samples were collected in August 2015. The pretailings dam spill median V concentration of 1 μg/L(29) is shown for reference.

The caption:

Figure 3. Geochemical profiles for pore water profiles PW-1, PW-2, and PW-3.

The caption:

Figure 4. X–Y plots showing the relationship between filtered V and other filtered element concentrations in stream, inflow, and pore waters. Stream water sample concentrations are mostly <10 μg/L and so are masked by the inflow and pore waters. Trends shown for the inflow waters (red squares) and for most of the pore water data (green circles).

The caption:

Figure 5. Electron microprobe X-ray maps showing V-bearing titanite and magnetite in Mount Polley tailings (POL-5) and V-bearing Fe oxide in the Fe oxyhydroxide (Fe oxyhyd) (POL-13).

The caption:

Figure 6. (a) K-Edge XANES spectra collected from Mount Polly mineral samples and selected V-containing standards. (b) Plot of pre-edge intensity vs pre-edge peak energy derived from V K-edge XANES spectra. V standard data from Hobson et al.,(72) Burke et al.,(21,44) Charaund et al.,(43) Bronkema and Bell,(73) and Wong et al.(74) (Td), (Py), and (Oh) refer to tetrahedral, square pyramidal, and octahedral coordination, respectively.

My kid knows more about this technique than I do; I'll ask him about it when he comes home again later in the summer.

Some discussion by the authors of their results:

V(III)-bearing magnetite and V(III)- and/or V(IV)-bearing titanite (Figures 5 and 6) were deposited within remobilized tailings and together with a large number of uprooted trees in the Hazeltine Creek catchment following the 2014 Mount Polley dam failure. It is also possible that smaller amounts of these minerals occurred within Hazeltine Creek channel and floodplain sediments and soils prior to the failure, given the relatively high V concentrations of some background soils.(26) A year after the tailings dam failure, high filtered concentrations of V in pore waters occurring at depths of 20 cm and especially 10 cm in Hazeltine Creek coincide with peak concentrations of Al, As, Ca, Cu, Fe, K, Mg, Mn, Ni, Zn, and Si and declines in ORP and pH (Figure 3). It is possible that these high concentrations reflect those in initial tailings dam pore waters transported with the spilled tailings, but this is unlikely for the following reasons. First, most of the tailings and interstitial water went into Quesnel Lake rather than Hazeltine Creek.(25) Second, we sampled in a very disturbed mixed river sediment rather than undisturbed layers of tailings. Third, we sampled a year after the spill, and the nature of the channel (high gradient, gravelly substrate) encouraged flushing by hyporheic exchange. Therefore, we propose that the high filtered V concentrations at depths of 10 and 20 cm arose from dissolution of V-bearing phases containing these elements just below the water–sediment interface.(66)...

...The significance of the Mount Polley tailings spill with respect to water quality and V transport is illustrated in Figure S4, where V flux (kilograms per year) and yield (kilograms per square kilometer per year) are compared to those of unaffected regional watersheds in British Columbia and other mining-affected watercourses around the world. The level of transport of V in the stream is elevated compared to those of nearby regional streams, even when the flux data are weighted by watershed area. In addition, under high-flow conditions, the V yield (measured at HC-9 in 2016) was comparable to (low-flow) yield values recorded in Torna Creek, Hungary, following the 2010 Ajka bauxite residue tailings spill.(71) The V transport data reported here show a departure from background concentrations and fluxes larger than the departure of those reported for Cu at Mount Polley.(37) Particulate transport of V appeared to be more dominant under high flow than low flow, suggesting physical mobilization of residual tailings could be an important transport mechanism for V during spring freshets and summer rainfall-runoff events. However, the bulk of the tailings remaining after our sampling in 2015 and 2016 was removed from the Hazeltine Creek watershed and returned to the tailings storage facility (L. Anglin, personal communication, 2018), suggesting that the effects of such physical mobilization could be minimal in the future.

Now the good news so you can not worry and be happy:

The weathering of mine tailings derived from dam failures such as Mount Polley can play a major role in V cycling in surficial environments. We have presented evidence that deposition of V-bearing tailings can lead to enhanced pore and inflow water V concentrations, especially when deposited or stored in environments where dissolution of primary (e.g., V-bearing magnetite and titanite) and secondary (V-bearing Fe and Al oxyhydroxides or clay) minerals also leads to greater V mobilization. However, these enhanced V concentrations can be naturally attenuated, and their potential ecotoxicity reduced, by formation of secondary colloidal Fe oxyhydroxides that reduce aqueous V to near background levels.

Don't worry about your Vanadium mine if you have lots of iron or titanium ores nearby.

None of this of course, implies that having a leaky vanadium flow battery in your garage would be good for you, but again, don't worry, be happy. I often hear that batteries are "green," and even though I know better, who am I to rain on the happy parade?

I hope you'll enjoy the up coming holiday weekend. I hope as well that we can all try to take a few minutes to remember a dead soldier, because that's what the holiday is supposed to be about.

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Reply The Fate of Vanadium after the Mount Polley Mine Tailings Spill. (Original post)
NNadir May 2019 OP
GemDigger May 2019 #1

Response to NNadir (Original post)

Thu May 23, 2019, 09:13 PM

1. Good article about a bad situation.

On the other hand, I want an oxidized piece. Just a little one.

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