Category Archives: Chemistry

Manganese on my mind

I spent much of the weekend reading up on, of all things, manganese chemistry. It turns out that there is a tourist mine in Salida, Colorado, that offers a glimpse of a manganese mine. It is rather dramatically called the Lost Mine and the tour includes a 4WD ride to the site. This tour is on the master list of future visits – my teenage kid groaned when I let this news slip out. Pretty funny.

What piqued my interest is a rock I picked up at a rockshop in Leadville recently. It is a low grade sample of dispersed rhodochrosite with a bit of pyrite grown into it. Rhodochrosite is a light pink to rose colored semi-precious crystalline mineral and also happens to be the state mineral of Colorado. It is fairly scarce and increasingly sought after for collection and for jewelry.

The light pinkish color of rhodochrosite stems from the oxidation state of Mn- Rhodochrosite is MnCO3. Depending on the ligand, the Mn (II) will have a high spin d5 electron configuration. The high spin d5 configuration requires a forbidden electron transition consisting of a jump between d orbitals and a spin flip on absorption of hv. Since this is a low probablility occurance, the molar extinction is low and accordingly, the color of the xtal is faint.

A fellow at the CC&V mine lamented that the ore body they process for heap extraction is loaded with manganese. He said that once they move the rock from the pit, the Mn levels cause it to become a pollutant (or some other term) as defined by the EPA. Manganese seems to be relatively abundant in parts of the Rockies.

Some Thoughts on Hazardous Goods

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When a customer orders a chemical from a chemical company, a series of events are triggered leading to the shipment. Every company has a unique business system for order fulfillment. Variable as the details may be though, certain aspects are shared by all companies.

There are special considerations for chemical goods that other manufactured items may not have. Chemicals must be packaged and shipped according to the nature of the material and to certain types of hazards that are present. The type of packaging is not just governed by good sense, but also by transport regulations.

Some substances are covered under regulations meant to control illicit drug manufacture or distribution. Diethyl ether, iodine, phosphorus, phenylmagnesium halide, phenylacetone, ephedrine, acetic anhydride, and many more seemingly ordinary chemical products are constantly under watch by authorities from behind the curtains.

Some substances may be used for explosives and munitions manufacture or use and prospective customers are screened accordingly. Other substances have been identified by the authorities as substances of interest. Phosphorus trichloride is one that comes to mind. Zirconium and titanium powders and components are subject to limitation also.

The kinds of regulatory constraints depend upon the compound of interest and whether or not it is an item for export or import. Import and export controls are in place for many reasons. The control of dangerous goods or illegal substances is an obvious goal. But the act of goods crossing the border is an opportunity for governments to temper the effects of international competition on behalf of homeland businesses through the imposition of duties.

International or domestic shipping of chemicals is rife with complications owing to the potential hazards of the cargo. Chemicals are classified according to their hazard and certain hazard classifications are barred from air transport or constrained to maximum package quantities. What is not transportable by air is usually fine for surface or ocean shipping, but these modes have their limitations as well. Fortunately, the regulations are internationally harmonized for the most part.

Woe is he whose container of hazardous goods is damaged or leaks at a foreign port of entry. Such an event may trigger remedies by the local authorities that will not only be very expensive, but will block the delivery of the material for a long time. This is why a smart manufacturer ships FOB -Free on Board. Once the order is on the truck and rolling off your mfg site, it is the responsibility of the customer thereafter.

For ocean shipments, the captain of the vessel has the final say as to what goes on the boat. Accordingly, your shipping container full of metal alkyls (Dangerous When Wet) will get loaded only at the pleasure of the skipper. It is not unheard of for the boat to sail without such cargos. More likely than not your container will get on the boat, but it will be placed at the top of a stack along side the railing. If there is a leak, over it goes.

A company that practices just-in-time inventory control with hazardous goods that come or go by boat must be prepared for delays and long transit times relative to air transport. It is always best to work with a logistics company that specializes in intermodal international shipments.

Significant New Molybdenum-Rhenium Find Announced

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A significant new ore deposit of molybdenum and rhenium has been announced by Ivanhoe Australia. The Merlin Mo-Re deposit is located in western Queensland, Australia, south of Cloncurry. The deposit is said to be worth $6 billion Australian. The core sample shown on a download contains 2.25 % Mo and 29 g/t of Re, according to the company. The principal ore is Molybdenite, or molybdenum sulfide.

Ivanhoe claims the advantages of the ore stem from the high grade and shallow depth. High grade ore requires a smaller refining facility. Ivanhoe says that its rhenium is not a byproduct.

Climax Molybdenum, a Freeport-McMoRan company, is also a producer of rhenium products. Climax Molybdenum operates the Climax mine on Freemont Pass near Leadville, Colorado, and the Henderson Mine near Empire, Colorado.

The geochemical association of Mo and Re is apparently not limited to a unique location. Molybdenum deposits at Ivanhoe, Climax, and Copaquire all have associated rhenium. Rhenium products such as rhenium pellets and ammonium perrhenate are supplied by Climax Molybdenum in addition to a variety of metallic moly and moly chemicals.

International PBX operates the Copaquire Mo-Re-Cu porphyry project in northern Chile. The company estimates that 47,000 to 60,000 lbs of indicated rhenium reside in their part of the district. According to PBX announcement, the indicated moly is between 203 and 253 million lbs and indicated copper lies between 364 and 563 millions lbs. The company is quick to point out that 25 % of the deposit is above ground in a mountain.

As of 2005 the three leading producers of rhenium were Chile, Kazakhstan, and the USA, with the USA having the largest known reserves. How the Australian find will alter this distribution is unclear at this time. The estimated rhenium trade in 2005 was $32 million.

Rest Stop on Freemont Pass at Entrance to Climax Mine

Rest Stop on Freemont Pass at Entrance to the Climax Mine

View of Climax Mine (Copyright 2009 All rights reserved)

The above photo of the Climax mine shows a processing building with what remains of Bartlett Mountain behind it. In fact there is a considerable lode of moly remaining in the mine.

The Gangues of Leadville

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The mining history of Leadville, Colorado, is well documented and the details are left to the reader to pry out of the internet. As a process chemist, my interest in mining is more directed to the geochemistry and milling of the ore. How did they get the pay out of the paydirt?

How does it come about that we can get our hands on particular elements like molybdenum, gold, silver, uranium, tungsten, vanadium, etc? How do the elements manage to concentrate into ore bodies that are worth the effort and expense to refine?

When you take the various mine tours around the country, the spiel offered by the guide is usually geared toward the lowest common denominator- our fascination with fabulous wealth. The miners were certainly taken with the possibility of wealth. Gold and silver mines are an easy sell because everybody has greed and everybody yearns to pluck a fat nugget of gold from a pan of gravel. Other types of mines are a tougher sell entertainment-wise and require a bit more explanation of the relevance of the obscure element that is being extracted.

Mining is an activity with good and bad effects. To sustain modern civilization, if you can’t grow what you need, you have to mine it. Mining is inherently extractive in nature and requires that large volumes of earth be disturbed. Open pit mining requires that overburden be removed and the mineral value be moved to a processing site. Material sidestreams are generated and must be dealt with.

Underground mines also generate large volumes of material that must be piled somewhere. To ensure responsibility for reclamation costs mining companies are required to put up a surety bond to cover the costs of future reclamation under 43 CFR section 3809.

The inevitable trade-off that a society must make is one of environmental insult for material goods. The balance point is always hard to find, and in fact is usually a moving target on account of politics, employment, and environmentalism.

Mining can have substantial effects on the landscape, the watershed, real estate, and the future tax base. Land that is not available for habitation or sustainable commercial use is fundamentally limited in potential value. An area covered with mine tailings, mine shafts, the occasional blasting cap, and acidic runoff is an area that requires cash infusion on a long timescale.

But if we enjoy the benefits of lead batteries in our cars, or silver jewelry, tungsten elements in our light bulbs, zinc plated wire fences, or the ten thousand other metal products in our lives, we must come to grips with the consequences for having such material goods. At some stretch point, everybody becomes a Luddite. Question: How much technological triumphalism can we take? Answer: Whatever the market says we can take.

Runoff Collection Pond from Mine Tailings in Leadville Mining District.

Our society has benefitted greatly from metallurgy. The compulsion to recover metals from the ground is one of the great economic forces in civilization. No amount of highminded pontification will stop it. Metals enable industry and war which are forever entangled in politics and greed. The goal is to be smart about how we mine elements from the ground so that maximum value of the surrounding land may be enjoyed. The enthusiasms of the time come and go. But metals are forever.

Mine Waste, Leadville Mining District August 2009

Plum-bummin’ in Leadville

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After an insane week in the lab a road trip to the cool meadows of the nearby mountain range was just what the doctor called for. It was the last weekend before the family- one teacher and one kid- return to school. Summer break 2009 is history.

We piled in the car and pointed it uphill towards Leadville, Colorado. The planetary atmosphere thinly blankets this insanely high mountain city. It was just what I needed to clear my scrambled mind. Nothing like blinding sunshine and mild oxygen starvation to reset a brain in chronic spasm from sensory overload.

Leadville sits at 10,152 feet above sea level. If you doubt the effect on your stamina, just take a short sprint in any direction. Or just plod up the stairs of your hotel. Lordy. All of those business dinners- all that lovely Cabernet and creme brulee- and years of driving a desk have caught up with me.

Leadville is located in the Colorado mineral belt and began to populate with fortune seakers about the time of the Colorado gold rush in 1859. Some placer gold was found in the streams, particularly in what was then called California Gulch, but for the most part Leadville became a silver camp.

In 1874, two investors with metallurgical training, Alvinius B. Woods and William H. Stevens arrived in Leadville and analyzed the muds found in the local sluicing operations. According to A Companion to the American West, edited by William Francis Deverell, (2004, Blackwell Publishing, ISBN 0-631-21357-0, p. 319) Woods and Stevens found the heavy black mud so problematic for gold sluicing was in fact composed of lead carbonate with high levels of silver. Woods and Stevens invested $50,000, quietly buying as many claims as they could and began hydraulic mining operations immediately.

By 1890 there were nearly 90 mines in operation employing 6000 miners. At its peak there were 14 smelter operations supporting the mines. Leadville was a genuine boom town with the expected mix of characters.

A mine is a hole in the ground with a liar standing at the top.

All mining towns have characters who go on to dominate local legends and stories. Among the well-known-for-being-famous rags to riches to rags players in Leadville are Horace and Agusta Tabor, along with Horace’s mistress and 2nd wife, Elizabeth “Baby Doe”.

To make a long story short, Horace was a struggling shop keeper who invested in a mine east of Leadville. Though it was salted by the previous owner to entice buyers, Tabor dug 25 ft further down the shaft and struck a rich and extensive vein of silver ore. The operation was called the Matchless Mine, after Tabor’s favorite brand of chewing tobacco.

According to the tour operators, Tabor operated the Matchless Mine 24/7 for 13 years, pulling an average of $2000/day of silver out of it. At its peak, the mine is said to have employed 100 people. Miners were paid the common rate of $3.00 per day to climb 365 ft to the bottom of the shaft for 12 hour shifts.

Matchless Mine Surface Workings

Tailings Dump Detail

The underground workings of the mine followed the vein structure and focused on sending concentrated ore to the surface. Buckets carrying approximately one ton of ore per load (my estimate) were tipped into ore carts and rolled into the ore house for hand sorting. The most highly concentrated and valuable ore was dumped down a chute for loading into a rail car and the gangue (or tailings) was dumped into the gulch.

An assay building (not shown) was on site to provide a continuous assay and accounting of silver sent to the smelter in Pueblo, Colorado. Unlike many other mine operators, Tabor owned a rail operation and had a spur at the mine for pickup and delivery of ore. Many mine operators had to employ mule-skinners to cart wagon loads of ore to a rail siding for transport to the nearest smelter.

In 1893 the repeal of the Sherman Silver Purchase Act and the collapse of the railroad industry bubble were part of a panic that lead to a crash in silver prices. Tabor lost everything and, as a respected public figure, was appointed postmaster of Denver for a short time. Eventually Tabor died at age 69 in 1899. Ex-wife Agusta had invested her divorce settlement wisely in Denver and lived comfortably. Widow Baby Doe Tabor was found frozen stiff in her shack at the Matchless Mine in 1935.

Matchless Mine Shack

All of the digging from the boom time of Leadville has left an enduring legacy for those who live in the watershed. Much of the mining activity occurred uphill, east of the city and as a result, that area is pock marked with many large colorful tailings heaps. While the colors are interesting to ponder and sample, the ground and surface waters are greatly affected by aqueous extraction of metals from these piles.

If you stand next to one of these heaps, you can’t help but notice the smell of sulfur. The ore and tailings are enriched in sulfides and once exposed to air and water, oxidation occurs to make corrosive runoff. This is a kind of heap leaching phenomenon that will eventually exhaust itself, but only at the cost of water quality.

Mantle of Insanity

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Recently I went to a local outfitter of camping gear to look for Coleman Lantern Mantles. As I was scanning the shelves a cherubic faced clerk came up to me and asked if I needed help. I said I was looking for lantern mantles.

When we arrived to the endcap where they were hanging, I asked him if they were still making radioactive mantles. He looked at me as though I were a bit of a loon. When I pressed the question, he balked and summoned his manager.

The manager, another youngster who was much more of an alpha male, scoffed at my question and tried to assure me that such a thing was absurd. Why in the world would mantles be radioactive? I tried to assure the youngster that, yes indeed, mantles were radioactive at one time because they contained thorium. At this point the manager was becoming visibly annoyed at his time lost addressing the questions of an obvious crackpot.

I recognized the patronizing tone he took and turned and left the store. As a child of cold war science, I have witnessed mantles sitting in a cloud chamber with ionized cloud streamers zipping every whichway from the innocent looking woven bag. Today, schools are terrified of chemicals and radiation science. Mr Manager missed out on a real experience by being born into the post-cold war world of bland science education.

So, my GM counter sits in my office clicking from the occasional background radiation piercing the GM tube. Eventually I’ll find a source to give it something more interesting to detect.

Gaussling’s 12th Epistle to the Bohemians. Elements Rock.

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Some acquaintances have asked about my new interest in geology. What’s the deal with rocks and mining?

What interests me is not so much the economic value and extravagant production of certain minerals and precious metals. What is of interest is the question of how it came about that there is such a thing as an ore body. An ore body is a geological formation which is defined by a localized concentration of certain substances. How does it happen that chemical elements can become concentrated from a more distributed condition?

Celebrity astronomers are often seen on cable channels pedantically nattering on about “Star Stuff”. OK, Dr. Skippy, what is star stuff and what does it do? What are the particulars about the local star stuff, ie., the earth? This is the realm of cosmochemistry and geochemistry- elective classes the TV glamour boys apparently skipped.

The nucleosynthesis of the heavy elements (C to U) and their subsequent ejection from exploding stars is an inherently dispersive process. Eventually, here and there, some heavy matter will aggregate to form a protoplanetary cloud which can then produce planetary bodies. Inevitably, some of the heavy matter is pulled into massive bodies dominated by the presence of thermonuclear fuels- that is, hydrogen and helium. Sufficiently large accumulations of these two highly abundant elements will compress and initiate a self-sustaining fusion reaction of hydrogen to form the (n+1)th generation of stars. All told, some heavy matter accumulates to form of planetary bodies while some of it siphons into the next generation of stars.

It is within the ability of gravity to concentrate matter into smaller volumes of space as a dense, bulk phase. The geometric shape that allows all of the mass to be as near the center of mass as possible is the sphere. This is why we don’t see planets shaped like cubes, pyramids, or ponies.

Once cooled well below incandescence, the matter in a sufficiently constituted and situated planet may begin to self-organize into chemical phases. Along the lines of the Three Bears allegory, Earth is parked in an orbit that is just right for the presence of liquid water. Irrespective of the needs of life, liquid water is critical for the eventual concentration of some elements into ore bodies.

Earth has a gas phase blanketing a liquid phase which wets much of the bulk rocky phase of the planet. A generous portion of water circulates in the maze of fractured recesses of the planetary crust. In the case of Earth, we know that our planet has a fluid core within a solid shell. This molten phase in the core energizes a kind of convective heat engine that will drive the shuffling motion of tectonic plates and episodic volcanic mass transfer on the surface.

Matter has gravitationally self-organized at the planetary scale on the basis of density. But what is perhaps most interesting to a chemist is the phase composition of the planetary solid matter. On cooling, a body of magma will sequentially produce precipitates representing different chemical substances. Over geological time this igneous rock may experience modification by the hydrothermal action of hot water under high pressure. Depending on its circumstances, parts of the formation may be depleted of soluble constituents or it may receive a deposit of new mineral species.

On the scale of planets, the earth has self-organized into bulk phases of matter- Solid, liquid, and gas. But at a much smaller scale, the earth self-organizes into domains of chemical substances. This is evident by simple inspection of a piece of granite. A piece of pink granite shows macroscopic chemical domains of potassium feldspar, quartz, and mica. While these three mineral components of granite are compounds and not pure elements, they nonetheless represent self-organization of species based on chemical properties.

The forces that drive chemical differentiation in mineral formation are ultimately thermochemical in nature. Large differences in Ksp lead to partitioning and phase separation of distinct substances. Subsurface formations may be approximately adiabatic on a short time scale, but over deep time they can slowly cool and equilibrate to yield a sequence of fractional crystallizations of metal carbonates, oxides, silicates, and aluminates giving rise to a complex bulk composition.

Speaking only for myself, coming to an understanding of how mineral deposits form is a kind of hobby. If I wanted immediate answers to specific questions, I suppose the most expedient thing would be to consult a geochemist. But where is the adventure in that? The answers are not the fun part. The real adventure is in the struggle to find the best questions. As it often happens, once you can frame the problem sufficiently, the answer falls out in front of you. Whoever dies with the greatest insight wins.

A Day Trip to the Caribou Mining District

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The ghost town of Caribou, Colorado, sits a few miles west of Nederland. As a group the mining towns of Caribou, Nederland, and Ward reside at the northeastern extreme of the Colorado Mineral Belt. This mineral rich formation cuts diagonally across the state, terminating near Durango in the southwest part of Colorado.

Every western state has its mining districts. The eastern reaches of the USA have hard rock mining districts as well. The Appalachians have a long history of hard rock mining. An example of eastern hard rock mining activity is the Foote spodumene mine in the Kings Mountain district in North Carolina.

The Ghost Town of Caribou, Colorado (Copyright 2009 all rights reserved)

While the Caribou district was previously known primarily for silver and tungsten, current hard rock mining operations by Calais Resources is targeting silver and gold. A blurb on the Calais website says that they do not use cyanide extraction in Colorado.

Calais Resources Comstock Shaft (Copyright 2009 all rights reserved)

This weekend the town of Nederland is celebrating its mining history with a miners festival. There were feats of strength and skill on display.

Hand drilling competition in Nederland July 2009

Across town at the Mining Museum, a 1923 Bucyrus 50-B steam shovel was in operation. This 130,000 lb beast was powered by an antique air compressor this afternoon because the boiler is not servicable. It turns out that this very machine was one of 25 taken to the Panama Canal to move dirt and rock. All were scrapped at the canal but this one. The canal was finished in 1914, so it must have been used for modification of the canal workings.

This machine was in service at the Lump Gulch Placer a few miles south of its present location until 1978. Bucyrus is still an ongoing concern in the mining equipment business.

Bucyrus 50-B Steam Shovel (Copyright 2009 all rights reserved)

As one drives into the Ward area from the north, the rock type evident in the road cuts changes. South St. Vrain canyon is largely granitic in nature. As one moves south into the Mineral Belt, the road cuts plainly reveal that a new dominant mineral type is present. Hematite or other iron oxide species are extensively represented in the rock.

My reading indicates that many metal ore bodies are the result of extensive hydrothermal modification of fractured or disturbed formations. Metal sulfide saturated, superheated water penetrates a disturbed formation leaving precipitates forming vein structures. In this way, many metal species are mobilized on the basis of solubility properties and are transported and concentrated leaving deposits enriched in a variety of useful metals.

The superheating of deep ground water and the subsequent partitioning and concentration on the basis of physical properties like solubility and volatility are what make the recovery of many elements possible. Without these concentration mechanisms many scarce elements would be too diluted in the parent formation to be feasibly isolated commercially.

Pyrite vug from a tailings pile (Copyright 2009 all rights reserved)

What Th’ Gaussling has found is that, while a PhD in Organic Chemistry isn’t entirely useless as a background for understanding rocks, it is closer to useless than I’d like. Edgemicated as I may be in a skinny band of chemistry, I have a lot yet to learn about minerals and petrology.

Hillbilly Engineering- A Homebuilt Kugelrohr

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In the mid 1990’s I had the good fortune to do a 1-year sabbatical replacement teaching gig at Ft Lewis College in Durango, Colorado. Of the several colleges in which I was lucky enough to be a faculty member, this school was absolutely the best. The chemistry department had a vitality that I had not experienced elsewhere, and sadly, would not be fortunate enough to repeat.

From my office high up on the mesa next to town I could hear the whistle of the steam locomotives of the Durango-Silverton Narrow Gauge Railroad. On friday afternoons a campus Native American group would sit around a single drum outside of Berndt Hall, each striking a hypnotic beat on the preserved skin while chanting and singing in the Ute language. While they were chanting the steam locomotives in the town below would blow their whistles, announcing their arrival for the tourists. The sound of it was an otherworldly experience I have not forgotten.

A prof I got to know at Ft Lewis, Dr. Irwin “Ike” Klundt, was a retired VP from Aldrich. He was to become a mentor and friend. It turns out that Ike was the inventor of the coffee pot kugelrohr that Aldrich offered in its catalog. West Bend, the appliance company, had a coffee pot manufacturing operation in Milwaukee, WI, where Aldrich was then headquartered. Ike learned that they would always have a few off-spec units coming from their mfg line, so he arranged to snag a few of these units. He recognized that these pots were built to contain heat and would be dandy ovens for his application. The large metal coffee pots were delivered to a one man shop somewhere in Milwaukee where the they would be converted to ovens for the Aldrich kugelrohr still, or “bulb-tube” short path distillation device to be more precise.

To provide agitation around the axis of the distillation train, an automotive pneumatic windshield wiper motor provided the needed reciprocating motion. It had a built-in tube that would serve to couple the bulb tube train to the vacuum line. The reciprocating motion of the motor removed the need for a sealed bearing as in the case of a rotary evaporator.

Aldrich sold a geat many of these units. In later years the kugelrohr was modified to enhance safety and ease of use. Aldrich has never been shy about pricing, so the price went way up as well.

I was thinking about this bit of history yesterday as I was operating my home-built kugelrohr. Sometimes shortpath distillation is needed and yesterday was the day for it. Using Ike as my inspiration, I horizontally configured a Buchi rotovap into a kugelrohr distillation unit with a still pot and a bulb tube receiver.

On a hotplate with a temperature indicator, I placed an 8 inch diameter sheet metal 90 degree elbow from Home Depot. The elbow, modified with a bit of aluminum foil, would serve as my hot air bath. The elbow and hotplate assembly is scooted over to the rotovap so that the still pot bulb is isolated in the “oven”. A dry ice/acetone cooling bath for the receiver bulb was made from the bottom of a plastic jar. It was notched on opposite ends to accomodate the receiver joints.

The setup works just like a Buchi-brand kugelrohr, but doesn’t carry the price of a luxury ocean cruise. I know that larger companies would not allow this kind of thing. They would frown on a chemist using his time to kludge together a piece of improvised equipment. Their safety people would not allow the operation of a device that was not purpose manufactured. But when you work for a small company this is one of the things you have to do, and I enjoy every minute of it.

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