The world’s biggest platinum producers have built stockpiles to last as long as eight weeks, helping them weather a strike that has begun crippling their mines in South Africa, the source of about 70 percent of global supplies.

Anglo American Platinum (Amplats) and Impala Platinum (Implats), the two largest, could continue to fulfil orders for six to eight weeks, spokesmen for the companies said.

Lonmin said last November that it had stockpiled 42 000 ounces of unrefined metal in the year to September and had 13 000 ounces of unsold refined platinum. It declined to say how long demand could be met.

“These strikes have been coming for some time and the companies have been preparing for them for 12 months-plus,” said Justin Froneman at SBG Securities. “They’re ready for this to drag out for a long time.”

The strike is costing the firms 9 900 ounces a day in lost production, valued at about $14.2 million (R158m).

At least 70 000 members of the Association of Mineworkers and Construction Union began striking last Thursday, calling for entry-level wages to be more than doubled to R12 500 a month.

Union president Joseph Mathunjwa said yesterday that the stoppage would continue as wage talks between the companies and the union resumed.

Amplats chief Chris Griffith, Implats chief Terence Goodlace and Lonmin chief Ben Magara said the three-day process was off to a constructive start and they were hopeful of a successful outcome. “In the end, resolution must be found.”

Platinum has risen 3.6 percent to $1 418 an ounce this year. Yesterday, Implats gained 1.47 percent to R120.49, Amplats rose 1.64 percent to R435.60 and Lonmin added 0.51 percent to R57.50 – Bloomberg