JOHANNESBURG (miningweekly.com) – Diamond miner Alrosa on Friday reported a 17% year-on-year decrease in its first-quarter production, as the shutdown of the Mir underground division weighed on its performance and lower-grade ores were processed from the Jubilee pipe.

The miner produced 7.42-million carats in the quarter, compared with 8.93-million carats in the corresponding period of 2017, and 10.07-million carats in the preceding quarter.

Alrosa is targeting diamond production of 36.6-million carats in 2018, first deputy CEO Igor Sobolev said on Friday.

The Aikhal division, comprising the Komsomolskaya pipe, Aikhal underground mine and Jubilee pipe, delivered 2.81-million carats in the first quarter, an 8% decrease on production of a year earlier. This was mainly owing to a decline in diamond output at the Jubilee pipe, where lower grade ore was processed.

The Mirny division’s, comprising alluvial deposits, the Mir underground mine and the International underground mine, reported a 46% year-on-year decrease in production to 1.17-million carats. The Mir underground mine was suspended in August 2017, after an accident. Alrosa is busy assessing technical solutions for resuming operations at the deposit.

The Nyurba division produced 1.90-carats in the quarter, which is 15% less than the same period of 2017. The decrease is mainly owing to lower output from the Botuobinskaya pipe, where production fell by 41% year-on-year as lower-grade ore was processed. The Nyurbinskaya pipe’s output increased by 3% year-on-year.

The Udachny division, production fell by 19% year-on-year to 817 000 ct, as openpit mining came to an end.

The Lomonosov division’s output increased by 49% year-on-year to 729 000 ct.

Meanwhile, Alrosa said that it sold 13.3-million carats of diamonds in the first quarter. This included 10.1-million carats of gem-quality diamonds at an average price of $154/ct and 3.2-million carats of industrial diamonds at an average price of $8/ct.

Rough and polished diamond sales amounted to $1.58-billion and $23.7-million respectively.