Name of the Mine
Boron mine.

Location
Boron, in the US state of California.

Mine Owner/s 
Rio Tinto subsidiary US Borax.

Brief Description 
Boron is home to one of the richest deposits of borates in the world. It produces one-million tonnes of refined borates every year, or about 30% of global demand.

Brief History 
The deposit was discovered in 1906, and underground mining operations started in 1925. Three underground operations were consolidated and the mining method switched to openpit mining in 1956.

Rio Tinto acquired the assets in 1967.

Primary Metals/Minerals 
More than 80 minerals are found at the Boron mine, including the four boron-based minerals in greatest demand by industry: tincal, kernite, ulexite and colemanite.

Secondary Metals/Minerals 
None stated.

Geology/Mineralisation 
The mine comprises a sedimentary sequence of tincal and kernite containing interbedded claystone enveloped by facies comprising ulexite and colemanite-bearing claystone and barren claystone.

Reserves 
Total proven and probable mineral reserves as at December 31, 2022, were estimated at 14-million tonnes.

Resources 
None stated.

Type of Mine
Openpit.

Mining Method 
Mining borates relies primarily on a combination of drilling, blasting and shovelling.

Major Infrastructure/Equipment 
The Boron mine includes an ore-crushing and conveying system, two process plants (primary process and boric acid plants), a shipping facility and tailings storage facilities. The mine also has on-site cogeneration units and a local power grid. Cogeneration uses natural gas to generate steam and electricity, which is used to run the mine’s refining operations.

Prospects  
Rio Tinto announced the successful completion of the transition of its heavy machinery from fossil diesel to renewable diesel at the Boron mine in June 2023, making it the first openpit mine in the world to achieve this milestone.

The change to renewable diesel brings an estimated carbon equivalent reduction of up to 45 000 t/y, comparable to eliminating the emissions of about 9 600 cars a year.

Contact Details
US Borax
Tel +1 733 270 6500

Sources
Rio Tinto. Website: https://www.riotinto.com/
US Borax. Website: https://www.borax.com/