* QR CEO says Mt Isa railway fixed as soon as end April
* Repair estimate reduced from 6 months to 8-12 weeks
* Line carries 5 pct of global zinc supply from mine to port (Adds background and detail of damage)
SYDNEY, Feb 25 (Reuters) - Australia's Queensland Rail said on Monday that it expects a railway hit by flooding this month, which disrupted zinc shipments from major producers such as Glencore, to be fixed as early as the end of April, sooner than it had expected.
The 1,000-km (620-mile) rail line is used by miners including Glencore, MMG Ltd and South 32 to carry zinc and lead concentrate from the Mt Isa region to port at Townsville, as well as by fertiliser producer Incitec Pivot Ltd.
"Our coordinated recovery crew will allow us to condense the Mount Isa Line's repair time down to eight to twelve weeks, subject to favourable weather and construction conditions," Queensland Rail Chief Executive Officer (CEO) Nick Easy said in a statement.
"That would have us reopening the line between late April and mid-May 2019," he added. Queensland Rail owns the line and had previously said it expected the repairs to be finished in under six months.
It was damaged in floods that covered vast tracts of Queensland's outback underneath muddy water earlier in February, killing hundreds of thousands of cattle and cutting off the region's mines and industrial producers.
The port at Townsville ships about 40 percent of Australia's zinc production, equal to about 700,000 tonnes a year or 5 percent of global supply.
Incitec Pivot said that the idling of its plants affected by the rail closure, owing to a lack of storage and ingredients arriving by rail, would cost about A$10 million ($7 million) a week in lost earnings.
Queensland Rail CEO Easy said some 400 workers were involved in the repairs and that 50 damaged sites on had already been repaired, but that 200 more remained still needed to be fixed.
"The damage ... includes track washouts and scouring, 16 damaged rail bridges, damage to track formations, and many locations where access roads, culverts and drainage have also been damaged or washed away," he said.
Glencore, MMG, South 32 and Incitec Pivot had no immediate comment when contacted after hours on Monday. (Reporting by Tom Westbrook; Editing by Muralikumar Anantharaman and Christian Schmollinger)