Posts Tagged ‘counter-current decantation’

The second part of the video on beryllium is now finished. You can watch it here:

This video has literally been 2 1/2 years in the making; my students Amy Zirbes and Nathan Jane videotaped our interview with subject expert Phil Sabey, the Manager of Technology and Quality at the Delta mill, in NOvember, 2007. This video discusses the history of mining beryllium at the mine site in the Spor Mountains of western Utah, including how the bertrandite deposit was discovered, and the land rush that occurred as a result (including an incident involving Maxie Anderson, who was head of Ranchers and the general counsel for Anaconda. Maxie Anderson went on to be one of three men to first cross the Atlantic in a helium balloon in 1978). This video also shows how bertrandite it is mined today by Brush Engineered Materials using open pit mines, then transported and processed at the concentration plant near Delta, Utah. The concentrated beryllium hydroxide is then shipped by rail to Elmore, Ohio for final refining into beryllium metal, alloys, and ceramics products. This episode also discusses Chronic Beryllium Disease, the main health hazard of refining or working with beryllium.

Chronic Beryllium Disease:

Beryllium dust, when in the air in concentrations of greater than 2 micrograms per cubic meter, gets inhaled and irritates the lung alveoli. The body treats it as an invading body, and sends white blood cells which surround the beryllium particle and form small granules called granulomas in the lungs. At this point, a person is said to have sub-clinical CBD or is “sensitized” to beryllium. Most people who are sensitized do not develop clinical CBD, but in about 2-5% of sensitized people, the immune system overreacts and the granulomas build up to where the lungs become stiff and respiratory function is impaired, leading to symptoms similar to pneumonia. There is no cure once CBD has set in, and the eventual result is painful death.

Before the effects of beryllium dust were known, a high number of workers in the beryllium industry were getting sick, especially in certain plants such as the old Brush Wellman plant in Lorain, Ohio. Beryllium in its ores (beryl crystals and bertrandite) is tightly bound to the crystal lattice and is therefore harmless. But refining bertrandite or beryl means that the beryllium is physically and chemically separated from the crystal, resulting in fine beryllium particles getting into the air unless precautions are taken. The effects of beryllium disease were well enough known by the mid-1960s that when the Delta concentration plant was built, safeguards were put in place that reduce beryllium dust to under 0.2 micrograms per cubic meter of air, or less than 10% of the maximum safety levels. Workers also wear respiratory equipment such as facemasks with filters to prevent even that level of dust from entering their lungs. There has not been any incident of chronic beryllium disease in the workers at the Delta plant.

Final beryllium metal, alloys, and ceramics are also fairly safe as the beryllium is part of the metal and not airborne. The danger occurs when these materials are cut, machined, or milled, which allows beryllium particles to get into the air where they can be inhaled. The only way to cure chronic beryllium disease is to avoid it in the first place by preventing beryllium dust from entering the air. Special precautions must therefore be taken in any business that handles beryllium. OSHA has been studying CBD and is likely to be coming out with new and even stricter standards soon.


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Topaz-Spor Mountain area

Topaz-Spor Mt. area

I am continuing this series of posts on the sources, mining, and refining of beryllium ore. I am in the middle of editing the interview my students did in Dec., 2007 of Phil Sabey at the Brush Resources’ Delta Concentration Mill and will have the final videos done by next week. Today I’ve been creating a series of Flash animations showing the geologic history of the Spor Mountain area where the bertrandite deposits are located. Today’s post will be on the refining process used at the Delta Mill to concentrate the bertrandite and beryl ore into beryllium hydroxide.

Bertrandite and Fluorspar

Fluorspar with Bertrandite

Refining Beryllium Ore

With only 0.65 % beryllium oxide (or 4.5 lbs. per ton of beryllium) in the final ore, a process had to be engineered to economically concentrate the beryllium for final processing. The properties that make beryllium useful also make it difficult to extract from its ores. Robert Maddox, Howard Gimperline, Jack Valliquet, Richard Shank, and other chemical engineers at Brush Wellman’s plant in Elmore, Ohio in the early 1960’s devised a unique solvent extraction process. With refinements, the process was seen to be economical and the go-ahead was given to build a concentration plant as close to the mine and to railroad transportation and a good water source as possible. In Dec., 1967 a groundbreaking ceremony was held at the mine and in April, 1968 a ceremony was also held at the mill site north of Delta, Utah. By the end of 1969, the plant was producing its first beryllium hydroxide concentrate.

Process for refining bertrandite

Process for Refining Bertrandite Ore

The solvent extraction process removes the beryllium by first crushing and wet grinding the ore in a ball mill, then leaching it with sulfuric acid and steam in rotating tanks at 95 ° C to dissolve the beryllium. Thickening agents are added which help to settle the sludge in a series of flotation tanks while leaving the beryllium sulfate in solution. The sludge is stirred by counter current decantation and pumped from tank to tank as the dissolved beryllium sulfate is washed over the side to continue the process. The remaining sludge is finally discarded to a tailings pile.

Sulfation Tanks

Sulfuric Acid and Steam are added to the bertrandite to dissolve the beryllium

The beryllium is then separated from the sulfate using an organic compound, then stripped from the organic by ammonium carbonate. Impurities of iron and aluminum are removed through steam hydrolysis, which leaves the beryllium in the form of beryllium hydroxide, which is vacuum drum filtered. Since beryllium dust is toxic, this entire process must be done in a sealed system, including the final packaging of the beryllium hydroxide into blue drums for shipment.

Panorama of the Brush Resources plant

Panorama of the Brush Resources Beryllium Plant

There are a lot of impurities in the bertrandite ore; some that gave problems early on were the high sodium content, the high uranium content, and the zirconium. The leftover filtrate still has appreciable quantities of uranium, so it is pumped to evaporation ponds, then shipped elsewhere for final uranium processing.

Beryl crystals

Beryl Crystals Ready for Refining

Once it was proven that this process could compete economically with the beryl extraction process already being used, the go-ahead was given to build the Utah processing plant. A site was selected near the Union Pacific railroad tracks and the Sevier River north of Delta and south of Lynndyl in west central Utah. The plant was completed in 1969 and began processing ore that had already been mined and stockpiled. Brush Wellman was awarded the prestigious J. C. Vaalor Award for Chemical Engineering in 1970 for the implementation of this process. In 1978, an addition was built on the plant to allow the processing of beryl ore, making the Delta plant the only facility in the United States that processes either form of beryllium ore. When beryllium was identified by the U. S. government as a strategic metal for its critical uses in the aerospace industry, beryl ore was purchased from mines in Brazil and stockpiled. Brush Resources has now purchased this strategic stockpile and is extracting the beryllium from it.

Pouring molten frit

Pouring Molten Beryl Frit

To recover beryllium from beryl crystals, the crystals must first be destroyed, since the beryllium is tightly bound in the beryl crystal lattice. The beryl is melted at 1700 ° C in a furnace, then quenched rapidly in water to break the crystal lattice and turn the beryllium particles into a frit, with the non-beryllium materials removed as slag. The frit is heat-treated at 1000 ° C in a rotary kiln, ground up in a ball mill, and leached with steam and sulfuric acid at 325 ° C in a rotating drum to dissolve the beryllium. This solution is added to the bertrandite solution in the flotation tanks to continue the process. In 1980, additional flotation tanks were added to accommodate the beryl solution.

Heat treater kiln

All of these processes require careful control and monitoring to improve yields and ensure safety. Using a Continuous Improvement Process, the Delta plant has added computer automation controls and improved laboratory analysis. New flocculent agents and organic solvents have improved the extraction yields, and the plant now processes ore at a 99% efficiency level. Around 400 tons of bertrandite and about 10 tons of beryl ore can be processed per day at the Delta plant.

Special thanks go to Phil Sabey for the tour of the Brush Resources plant and for providing the brochures, Powerpoint presentations, and photos upon which this post is based.

Phil Sabey in Chem Lab

Phil Sabey in Analysis Lab

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