Constancia is being developed at an estimated cost of US$1.5 billion primarily as a copper mine but it will also produce gold and silver.
The gold arrangement, announced late Monday, follows a deal in 2012 that Silver Wheaton signed to acquire all of the silver production from Constancia.
Silver Wheaton will make an US$135 million deposit on future deliveries of 50 per cent of the project's gold. Hudbay will retain the other half of Constancia's gold production.
Silver Wheaton will pay the lesser of US$400 per ounce that it buys, subject to an inflationary adjustment, or the prevailing price per ounce of gold delivered.
First production at Constancia is expected in the second half of 2014 with full production in 2015.
Silver Wheaton has also updated its five-year production guidance on due in large part to delays at Barrick's Pascua-Lama project which was to supply the company with silver.
Barrick said last week it has suspended construction of Pascua-Lama in the face of a weak gold price, rising costs and other problems at the project.
In 2017, Silver Wheaton is expected to produce approximately 42.5 million silver equivalent ounces, including 210,000 ounces of gold, down 13 per cent from its earlier guidance.
Silver equivalent production this year is still expected to top 33.5 million ounces.
On the Toronto Stock Exchange, Silver Wheaton shares slipped 30 cents to $23.32, while HudBay (TSX:HBM) was ahead 23 cents at $8.83.