Peak metal

I was asked by The Green Man to write something on peak metal. It took me a couple of days to put this together from various sources. As I commented in a previous thread, many metals are becoming rare. Many people know of my views on peak oil. Oil has nearly tripled in value in the past 3 years because demand is outstripping our ability to bring it to market. The same phenomenon is going on with many metals. There is one big difference between metals and oil. In general, metals are recyclable. Oil isn’t. Once oil is burned, it is gone. Scrap metal amounts to around 40% of the production of many metals. But, peak production problems are out there.

Let’s start with iron. It is a very common element in the earth’s crust, about 6%. In Michigan’s Iron range, used to reside a huge, high grade iron ore band, called the Mesabi, which from the Ojibwa language means ‘giant’. This 110 mile long, 3 mile wide and 500 feet thick ore deposit was discovered in the 1880s and started out with ores as high as 70% iron. As with all mineral exploitation, the highest grade deposits are mined first. Energetically this is smart. One gets the most iron by moving the least rock. But, over time the ore grade drops and one must move more rock per unit iron obtained. Below is a picture showing the cycle through which the Mesabi deposit went from
http://www.eoearth.org/article/Limit...es_(historical)

[attachment=1]

. The dotted line at the top of the picture is the percent iron and how the iron content declined over time, until the Mesabi deposit was nearly completely mined out.

In the 1930’s geologists thought that there would not be much of a future for the iron range after the Mesabi was tapped out. But, what happened, is what happens always in mining. When the high ore grades are used up, lesser grades are tapped. In the case of this region, taconite (banded iron formation, also known as BIFs) became the main source of iron ore. Taconite was not considered an ore in the 1930s. It contained only 25% iron. Today it is being mined. Energetically one must move 4 units of rock for each unit of iron, whereas, in 1900 one had to move 4 units of rock and obtained 3 units of iron. Clearly in the mining process, today’s lower quality oil is 3x more expensive than yesterday’s iron ore. When taconite is tapped out and on is forced to go to 10% ore grades, one will move 10 units of rock to obtain 1 unit of iron. As oil prices rise (which they inevitably will), the cost to obtain iron will rise as well. From the example of iron, one can see that even abundant crustal elements have issues concerning quality.

Copper.

Copper is an interesting metal where it comes to peak metal. A recent PNAS article discussed metal use and sustainability. While most of the conclusions were optimistic, some weren’t. Consider the curves of cumulative copper discovery and cumulative copper extraction. Gordon et al. note that since 1925 the rate of increase in copper ores discovered has gone up at 0.63%. But the rate of increase of extraction has gone up at 3.9%. Here is the picture. One thing every grade school child learns is that if one finds 5 quarters and loses 5 quarters, the number of quarters Johnny has is zero quarters. The cumulative extraction of copper is about 66% of the cumulative discovery (the chart below is on a logarithmic scale.) Clearly by 2050 the discovery and extraction curves will meet and there will be no (or little) future copper mining.

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But that is ok, because copper can be recycled. But it isn't. Because of population increase and the increasingly affluent societies in the world, the per capita copper use is less and less. And, with peak oil coming into play one needs to take a look back to see what energy people required to obtain this wondrous metal. Paul Roberts informs us.

Paul Roberts, The End of Oil, (Boston: Houghton-Mifflin, 2004), p. 25

“By some estimates, every man, woman, and child in these early cities required a half ton of firewood a year, a requirement that put an enormous strain on local forests. Factor in the added energy demands from a primitive industry like copper smelting - a ton of firewood was needed to smelt ten pounds of metal - and you have the beginnings of the earliest energy crunch. For perhaps the first time in history, humans could see the threat that lay in the gap between fuel demand and fuel supply. ”

Without energy smelting becomes a huge problem. But then, with lower grades of ores, energy also becomes a huge problem. Like iron, copper used to be mined from much richer ores than are currently being used.

Donella H. Meadows, Dennis L. Meadows, Jorgen Randers, Beyond the Limits, (Post Mills, VT: Chelsea Green Publishing Co., 1992), p. 84-85

“Figure 3-16 shows what mineral depletion looks like-gradually decreasing ore concentration. Figure 3-17 shows the consequence of depletion. As the amount of usable metal in the ore falls below 1 %, the amount of rock that must be mined, ground up, and treated per ton of product rises with astonishing speed. As the average grade of copper ore mined in Butte, Montana, fell from 30% to 0.5% the tailings produced per ton of copper rose from 3 tons to 200 tons. This rising curve of waste is closely paralleled by a rising curve of energy required to produce each ton of final material. Metal ore depletion hastens the rate of fossil fuel depletion.”

Here is Fig. 13.6 from their book

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Here is the problem. In going from 30% ore to 0.5% ore, one goes from moving 3 tons of rock per ton of copper to moving 200 tons. This is intrinsically 18 times more energy intensive!

Zinc.

This quotation from Gordon et al, says it all:

R.B. Gordon et al, “Metal Stocks and Sustainability,” PNAS v.103(2006):5:1212-1213

Zinc: A Story of Dissipative Uses. As with copper, the use of zinc increased rapidly over the last century and a half. Jolly (15) estimated that, of 73 Tg of zinc placed in service in the U.S. between 1850 and 1990, 23 Tg remains in use, only 4 Tg were recycled, and 46 Tg (63%) were lost in waste repositories or were dissipated.

Platinum

A sad story. It is used in car exhaust systems. But there isn’t enough to do this for a long time. It is found at the rate of 5 parts per billion in the crust. But the quote below talks about the platinum group.

R.B. Gordon et al, “Metal Stocks and Sustainability,” PNAS v.103(2006):5:1213

In a review of world platinum deposits Råde (28) found 66.5 Gg of identified platinum resources. Our independent assessment has yielded 97.1 Gg of platinum-group metals as the total resource of which 67.3 Gg containing 37 Gg of platinum remains unmined. Råde reported 90% recovery in mining and 88% efficiency in milling and smelting, which indicates that a total of 29 Gg of platinum-group metals is available for future use.

Platinum is prized as a jewelry metal, but it is also a superb catalyst. It is widely used in automobile exhaust systems (1–5 g per vehicle) and in a variety of industrial applications. Suppose that the 500 million vehicles estimated to be in use worldwide in 2000 were converted to fuel cell operation operating on pure hydrogen (i.e., no reforming of fuel needed), that the platinum requirement was 0.4 g/kW, that the average vehicle power was 75 kW, that the fuel cell life was 10 years with a 90% recycling rate, and that recycling achieved 50% recovery of the platinum content. The platinum stock-in-use for these vehicles would be 15 Gg. Maintaining this stock would require a flow of new metal into use of ~1 Gg per year. If all of the remaining lithospheric stock of platinum were devoted to operating a fleet of 500 million vehicles with fuel cells, the platinum resource in the lithosphere would sustain this fleet for ~15 years. There would be competition for this platinum for use in jewelry, stationary power fuel cells, industrial catalysts, and catalytic converters for motor vehicles still using petroleum fuel.

Gallium

This element is used in high efficiency solar cells and fast semi-conductors. It is found in the earth’s crust at 16-18 parts per million. There isn’t enough of it to make a spits worth of difference.

[cite=David Cohen, Earth Audit," New
Scientist May 26, 2007, p.35]
"Take the metal gallium, which along with indium is used to make indium
gallium arsenide. This is the semiconducting material at the heart of a
new generation of solar cells that promise to be up to twice as
efficient as conventional designs. Reserves of both metals are disputed,
but in a recent report Rene Kleljn, a chemist at Leiden University in
the Netherlands, concludes that current reserves 'would not allow a
substantial contribution of these cells' to the future supply of solar
electricity. He estimates gallium and indium will probably contribute to
less than 1 percent of all future solar cells--a limitation imposed
purely by a lack of raw material."

Indium

The other element in the Gallium-Indium-Arsenide chips is found at 50 parts per billion in the crust. This is not something upon which to base our technology.

I will finish this with a quotation from Cohen.

David Cohen, Earth Audit,"
New Scientist May 26, 2007, p. 38

"If Demand Grows...

"Some key resources will be exhausted more quickly if predicted new
technologies appear and the population grows

Antimony 15-20 years Silver 15-20 years
Hafnium ~10 years Tantalum 20-30 years
Indium 5-10 years Uranium 30-40 years
Platinum 15 years Zinc 20-30 years."

If one looks at the performance of a metals heavy mutual fund (ignax) compared with an oil heavy mutual fund (ienax) over the past 4 years, one sees that metals have been outperforming (getting scarcer more rapidly) than oil. Ignax is up over 100% while Ienax is up only 90%. The market place is clearly saying that peak resources are just around the corner. Like it or not, the world is running out of resources. I am invested in these increasingly scarce commodities.

[quote=grmorton;2094303

Here is the problem. In going from 30% ore to 0.5% ore, one goes from moving 3 tons of rock per ton of copper to moving 200 tons. This is intrinsically 18 times more energy intensive!

[/QUOTE]

Correction (one too many toddies last night). it should be ~67 times more energy intensive.


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