Tansey, 24, had his contract terminated by the Super League club last week for a third breach of discipline in 12 months.
He is expected to make his debut for the Rams in tomorrow’s Northern Rail Cup tie with Doncaster at Keepmoat Stadium.
Halifax have been dealt a significant blow ahead of their Championship defence with Mike Ratu out for four months.
The ex-Leeds Rhinos centre, who joined from Hull KR this winter and has Super League experience, broke his arm in last week’s 50-10 win over Oldham.
Halifax continue their Northern Rail Cup campaign at Whitehaven tomorrow when holders Batley Bulldogs entertain Gateshead Thunder without second-row Jason Walton who received a two-match ban for a spear tackle against Leigh.
Paul Mennell is available after his red card for a high tackle in the same match was deemed ‘sending off sufficient’.
Danny Grimshaw (hamstring) has a fitness test ahead of Hunslet’s visit from Workington, Sheffield Eagles are missing Misi Taulapapa and Quentin Laulu-Togagae at Leigh, Jonny Presley is doubtful for York’s journey to London Skolars while Keighley’s Ryan Benjafield may return from a shoulder reconstruction when they host Toulouse this evening.