Gemfields said its new $15 million sort house in Mozambique features an automated process to allow for greater production levels.
London—Gemfields has opened a $15 million ruby sort house at its Montepuez ruby mine in Mozambique.

The colored stone miner said the state-of-the-art facility will significantly raise production levels, allowing it to “consistently deliver a greater volume and spectrum” of rubies.

It uses the natural properties of rubies as a means for automated sorting, Gemfields said.

The raw material is first washed and then passed under ultraviolet light. Since rubies naturally fluoresce under UV light, optical sorters can detect the fluorescence and then use blasts of air to direct individual rubies to separate channels for further sorting and grading.

Gemfields said using programmable logic controllers and data software under the UV light is faster, more reliable and more efficient than the human eye. It also allows for the identification of a finer material component than before.

The facility also accommodates more wash plants, now washing the equivalent of 10,000 tons of ore per day.

“Previously the sorting of rubies was largely manual, but it is very exciting to now introduce automated sorting, which will require minimal manual sorting,” said Kaung San, the company’s ruby grading supervisor. “Our productive capacity will increase exponentially.”

Gemfields said the automation of the sorting process won’t result in a reduction in its workforce.

In fact, increased productivity at the sort house means Gemfields will expand its current active mining area, requiring the company to hire more people.

The colored stone miner also said the manual aspect of the sorting process—the categorization and grading of the rubies—will require more highly skilled employees. Rather than look outside the country for this expertise, Montepuez is training a group of Mozambican gemologists who will specialize in the selection and classification of rubies.

Gemfields said its $15 million investment in the sort house is the largest of its kind in the Cabo Delgado province of Mozambique.

Looking ahead, the colored stone miner said the new sort house will be complemented by the addition of a new thickener to the wash plant this year, increasing capacity from 125 tons per hour to 150 tons per hour.

Two high-capacity pre-screen plants also will be added to remove the finer particle material prior to being fed to the wash plant, resulting in a greater concentration of material of the desired size.

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