Mineral Processing Engineering

Microwave Digestion

We conducted research related to Microwave Digestion in hope it would lead to the improvement of analytical procedures used to characterise metal and mineral samples. In particular, this research is directed to the reduction in time, complexity, and expense of sample dissolution for chemical and instrumental analysis.

The rapid development of automated instrumentation has enabled the analytical chemist to perform an ever-increasing number of analyses. Unfortunately, sample preparation has not kept pace with the development of analytical instrumentation.

The Bureau previous investigated a method for the rapid, low-cost dissolution of samples in plastic pressure vessels. The method consisted of acid digestion in sealed plastic bottles that were heated in a boiling water bath. After digestion the samples were water cooled. Boric acid solution was then added to each bottle, and the solutions were reheated in the boiling water bath to dissolve any precipitated fluorides.

Because dissolution was carried out in closed plastic vessels, contamination was avoided and volatile gases such as SiF4 were retained. Samples could be prepared for analysis in less than an hour, and many elements could be analyzed from this single dissolution. In an effort to speed up dissolution time even further, the Bureau has introduced a significant improvement by

By David|2018-07-22T14:37:43+00:00July 22nd, 2018|Categories: Assaying|Comments Off

Improve Strength of Steel Alloys

Improve the strength and other properties of steel alloys.

Approach

Research by the U.S. Bureau of Mines indicates that steels melted and solidified under high nitrogen pressure acquire yield and tensile strengths that are up to four times the strengths of comparable stainless steel alloys without nitrogen. Fatigue strength, creep strength, and other mechanical properties are also improved. Strengthening occurs by two mechanisms: (1) increasing dissolved nitrogen in the lattice and (2) formation of dispersed metal nitride phases.

Nitrogen Alloying

Nitrogen alloying of a steel is generally done by introducing metal nitrides during melting of the steel. The concentration of nitrogen is limited to its equilibrium solubility at 1 atmosphere. For face-centered-cubic (fee) iron, that solubility is approximately 0.4 weight percent (wt%). For body-centered-cubic (bcc) iron, solubility is 0.05 wt%. This solubility limitation can be overcome by melting the metal in a pressurized vessel.

European steelmakers currently have metal-processing systems that can melt and pour tons of steel under nitrogen pressures exceeding 4 megapascals (MPa) (40 atmospheres). They have achieved nitrogen concentrations as high as 1.0 wt% in these (stainless) steels. The tensile strength is approximately twice

By David|2018-07-19T18:57:22+00:00July 18th, 2018|Categories: Smelting - Melting - Refining|Tags: 992|Comments Off

Recovering Platinum-Group Metals in Catalytic Converters

Develop new technology to encourage domestic processing of automobile catalytic converters for recovering platinum-group metals.

Background

Automobile catalytic converters are used to convert pollutants in automobile exhaust into water vapor, carbon dioxide, and nitrogen. About 1 million troy ounces of platinum-group metals arc used each year in the United States to manufacture catalytic converter. It has been estimated that about 60 pct of the used catalytic converters are being collected. Most of these used catalytic converters were not processed in the United States but were exported to Japan or Europe for processing. In 1991, about 250,000 troy ounces of platinum- group metals were recovered from scrap catalytic converters collected in the United States. Each short ton of decanned catalyst may contain 30 troy ounces of platinum-group metals valued at over $ 15,000. Development of an economic process for the recovery of platinum-group metals that can be operated on a small or large scale may increase the percentage of catalytic converters collected and encourage domestic processing to recover a platinum-group metal concentrate. This would significantly decrease the dependence of the United States on imports for these critical and strategic metals.

By David|2018-07-19T18:59:40+00:00July 18th, 2018|Categories: Recycling|Tags: 992|Comments Off

Foam Concrete Seals for Abandoned Mine Shafts and Adits

Investigate and demonstrate the possible use of low-density (45-lb/ft³) foam concrete for sealing abandoned mine openings. Although foam concrete has been used in the construction and geotechnical industries tor some decades, it has not previously been used in abandoned mine shaft reclamation.

Approach

A structurally engineered permanent mine seal for an abandoned coal mine shaft, using low-density foam concrete and other appropriate structural materials, was designed by the Bureau and installed at a field site, the No. 22 Shall in Logan County, West Virginia. The field work was conducted by a private contractor under the supervision of the West Virginia AML Section (WV AMI).

The No. 22 Shaft is situated immediately adjacent to a frequently traveled county road, A few feet away from the shaft is a branch of Pine Creek. On the other side of the road is a railroad line that serves an active mining operation located several miles away. The shaft measures 9.5 by 9 feet in cross section and is about 300 feet deep. It was used at one time as a dewatering shaft and still contains two large-diameter dewatering pipes with steel drive shafts inside them. Before

By David|2018-07-19T19:01:45+00:00July 18th, 2018|Categories: Uncategorized|Tags: 992|Comments Off

Gold Prospecting in Quebec

Gold Prospecting in Quebec

The prosperity of any nation depends, to a large extent, on its natural resources such as oil, coal, metal, timber, water-power, and fertile soil. Each one of these resources forms the basis of a huge industry. The mining and smelting industry ranks among the first since it paves the way for a number of other industries. The mines and smelters provide a market for electric power, coal, timber, and agricultural products: other industries in turn provide a market for metals and non-metals.

The real pioneering, however, is done by the prospector who goes into the wilderness to search for the ores from which the metals are to be extracted for the use of men. Prospecting is an interesting and fascinating occupation. There are many difficulties and hardships in the way but the lure of gold and the vision of finding an outcrop that may develop into a large bank account, within a reasonably short time, will urge the prospector forward.

Thus, on the outskirts of this northern hemisphere hundreds of prospectors are searching and toiling and of whom nothing is known or heard until they reach civilization and

By Jorge|2018-07-14T13:31:05+00:00July 10th, 2018|Categories: Uncategorized|Comments Off

Prospecting for Fine Gold

Methods used to determine the quantity of gold present in a sample vary according to the type of prospecting being done, and the manner in which the work is carried out. These methods can be classified as:

dry-blowing
panning
other gravity concentration methods such as jigging, tabling and cradling
centrifugal concentrating
amalgamating
spectrographi analysis
fire assaying
chemical testing

Dry-blowing

Dry-blowing of powdered samples is practised where water is extremely scarce. Harris (1920) mentions shaking mechanisms designed to work on the same principle, and some variations include bellows or blower to give a more constant air velocity. A process, which depends for its effectiveness on a variable factor such as the wind, tends to be inaccurate, and as well as that it is very dusty work. The method is therefore used mainly by individual prospectors in desert areas and can be expected to detect only coarse gold.

Panning and other gravity methods of concentrating

For assessing values in gravels, soils or outcrops, the miner’s pan, when used by an experienced prospector, is a tool that can hardly be surpassed for simplicity, speed and sensitivity, and a high degree of accuracy can be achieved. For general prospecting the only equipment required is

By Jorge|2018-07-11T16:24:37+00:00July 10th, 2018|Categories: Uncategorized|Comments Off

The 10 DEEPEST Diamond Mines in the World

The accumulation of diamonds has come a very long way since the first examples of this hugely precious stone were discovered in India in around 400 BC. Most of the world’s diamond deposits were formed over 1 billion years ago, yet gaining access to them has necessitated the development of hugely sophisticated modern technology.

As mining engineering has become more advanced, so the pits being excavated have become deeper. So here is our guide to the ten deepest diamond mines in the world.

Click on any of the photos for a close-up of the

Deepest Diamond Mines on Earth

10. Jagersfontein – 275 meters

South Africa is undoubtedly the dominant country in diamond mining, and this abandoned open-pit mine in the Free State province has a special place in the nation’s mining history. Two of the ten biggest diamonds ever discovered were mined at Jagersfontein, while the hole in the earth excavated at Jagersfontein has been confirmed by independent research to be the largest ever, at 19.65 hectares (48.6 acres).

9. Jubilee – 320 meters

Russia is also a major player in diamond mining, and the Jubilee mine (known as the Yubileyny diamond

By David|2018-07-07T18:44:54+00:00July 5th, 2018|Categories: Uncategorized|Comments Off

The 10 MOST VALUABLE Diamond Mines in the World (by Reserves)

Diamond mining is one of the most prestigious and profitable industries in the world. The ten largest diamond mines in the world by measurable reserves contain more than one billion carats of recoverable diamonds, and this naturally translates into many billions of dollars. It’s thus intriguing to look at how these carats are distributed.

10. Botuobinskaya – 69.3 million carats

Botuobinskaya diamond mine is owned by Nyurba Mining, a division of Alrosa. Located in Nakyn, Russia, Botuobinskaya has reserves of 69.3 million carats, and is an extremely recent find, as it only began operating in 2015. It is expected to produce 1.5 million carats of diamonds annually over the next 40 years.

9. Venetia – 71.8 million carats

Venetia is one of the most important diamond mines for the infamous De Beers company. Situated 80 kilometers from Musina in Limpopo Province, the Venetia mine is the largest diamond producer in South Africa, with 4 million carats being churned out by this diamond mine on an annual basis. Venetia is current a conventional open-pit mine, but work is underway to convert it to an underground project in the coming years.

By David|2018-07-08T06:51:10+00:00July 5th, 2018|Categories: Uncategorized|Comments Off

Dry Grinding Equipment & Plant

dry grinding equipment and system

By David|2018-06-15T15:54:06+00:00June 15th, 2018|Categories: Grinding|Comments Off

How to Fast Track Construction a Mining Project

The construction schedule is a very important part of any complex construction project. If used properly it can alert the construction manager to a variety of problems including ability to complete the project on schedule, overtime construction required to keep on schedule, increase in construction personnel, impact of late equipment arrival, impact of detail engineering delays, and other potential problems.

The construction manager should be intimately aware of the schedule and include it in all weekly discussions with the contractor. Variances in schedule dates should be noted. If there is an impact on the completion date either an alternative should be formulated or management informed of the delay.

When delays of final construction completion are anticipated there are generally some means to bring the completion back on schedule at an additional cost. Decisions concerning cost of ameliorating delays should be made by the overall project management because other areas of the project may be delayed also. It usually is not practical to keep one part of a construction project on schedule by paying extra for timely completion when another part of the project cannot be completed