Name of the Mine
Boroo and Ulaanbulag mines.

Location  
Boroo is located in Selenge province, about 140 km north-west of Ulaanbaatar, in Mongolia. Ulaanbulag is a satellite mine in Tuv province, about 19 km south-east of the Boroo mine and processing complex.

Mine Owner/s  
Mongolia-focused precious metals producer and developer Steppe Gold owns the operations through its wholly owned subsidiary Boroo Gold.

Brief Description  
Boroo and Ulaanbulag are integrated openpit gold operations covering a combined land package of about 6 594 ha. 

The operating portfolio comprises the Boroo hard-rock and placer deposits, the Ulaanbulag satellite deposit and the Bor Nuur exploration licence. 

Ulaanbulag ore is transported to the established Boroo processing complex and the two mines share the mining fleet, processing facilities and carbon-in-pulp plant. The operation is based on nominal mining capacity of about 50 000 t/d and an annualised mill-feed rate of 5 000 t/d, or about 1.8-million tonnes a year.

Brief History  
Boroo Gold acquired the Boroo project in 1997. 

AGR Limited acquired an initial 85% interest in the company in 1998 and increased its interest to 95% in 2000. Cameco Gold, Centerra Gold's predecessor, acquired AGR between 2002 and 2004, and Centerra obtained the remaining 5% of Boroo Gold in 2007. 

The Boroo mill started processing ore in 2003 and achieved commercial production on March 1, 2004. Boroo acquired Centerra's Mongolian business, including Boroo and Ulaanbulag, in October 2018. Processing Ulaanbulag ore started in 2021. Steppe Gold acquired Boroo Gold in 2024, consolidating the operations within its Mongolian portfolio.

Primary Metals/Minerals  
Gold.

Secondary Metals/Minerals  
Not stated.

Geology/Mineralisation  
The Boroo area is underlain by folded Lower Palaeozoic Haraa flysch sediments, comprising siltstone, sandstone and greywacke, intruded by granite and granodiorite of the early Palaeozoic Boroo Complex. 

Boroo is an intrusion-related, low-silica gold-arsenic sulphide system. Bulk mineable mineralisation is hosted in a strongly quartz-sericite altered and sulphidised, shallow-dipping zone controlled by the Boroo fault. 

Mineralisation comprises gold-sulphide zones containing mainly pyrite and arsenopyrite, and subordinate, locally high-grade gold-quartz veins. 

Ulaanbulag is geologically similar and is controlled by the shallow-dipping Ulaanbulag fault. Its mineralisation also comprises gold-sulphide alteration zones and gold-bearing quartz veins hosted mainly in altered granitic rocks.

Reserves  
Boroo had total proven and probable reserves as at February 1, 2024, of 24.35-million tonnes grading 0.72 g/t gold, containing 567 000 oz. This comprised 16.542-million tonnes of proven reserves grading 0.74 g/t and 7.80-million tonnes of probable reserves grading 0.69 g/t. Ulaanbulag proven and probable reserves totalled 6.17-million tonnes grading 0.66 g/t gold, containing 130 000 oz. This comprised 3.54-million tonnes of proven reserves grading 0.71 g/t and 2.64-million tonnes of probable reserves grading 0.58 g/t.

Resources  
Boroo had measured and indicated resources as at January 1, 2024,  of 44-million tonnes grading 0.57 g/t gold, containing 805 000 oz, while inferred resources totalled 1.3-million tonnes grading 0.789 g/t, containing 33 000 oz. 

Ulaanbulag measured and indicated resources totalled 12.4-million tonnes grading 0.53 g/t gold, containing 213 000 oz, while inferred resources totalled 4.3-million tonnes grading 0.38 g/t, containing 52 000 oz.

Type of Mine
Openpit mines.

Mining Method  
Boroo and Ulaanbulag are mined using conventional openpit drill, blast, load and haul methods. Five-metre benches are used, with ore mined on half benches to improve grade control in the shallow-dipping mineralised zones. 

Major Infrastructure/Equipment  
Shared infrastructure at Boroo includes the openpit workings and mining fleet; crushing and ore-feed facilities; grinding and gravity-concentration circuits; leaching, carbon-in-pulp adsorption and gold-recovery facilities; cyanide-detoxification and arsenic-precipitation circuits; heap-leach pads; a zero-discharge tailings-management facility; dewatering and return-water systems; chemical, reagent and fuel storage; a 110 kV grid connection; water-treatment facilities; warehouses, workshops, offices, accommodation and security facilities. 

The principal mining fleet includes hydraulic excavators, 50 t and 100 t haul trucks, and supporting mobile equipment. Ulaanbulag ore is hauled about 19 km to the Boroo processing complex.

Prospects  
The combined reserve base is expected to support operations until 2031. The 2024 mine plan envisaged openpit mining continuing into the first half of 2030, followed by the processing of stockpiled mill and heap-leach ore until 2031. The Bor Nuur exploration licence and remaining prospective areas within the consolidated land package provide further exploration potential.

Contact Details 
Steppe Gold  
Tel +976 7732 1914
Email elisa@steppegold.com
Website https://www.steppegold.com