Arrow Minerals (ASX:AMD) said metallurgical test work at its Niagara bauxite project in Guinea shows that alumina recovery averages 81% from feed for low-temperature digestion, and 91% from feed for high-temperature digestion across all samples, according to a Tuesday Australian bourse filing.

A series of 12 samples were selected for analysis, consisting of nine high-priority plateau composites, and three lower-priority individual drillhole composites. They were submitted for analysis to assess the quantities of available alumina that may be recovered using the Bayer process.

The results also showed consistent low reactive silica averaging 1.5% for low-temperature digestion, and 2.1% for high-temperature digestion.

The firm's managing director, David Flanagan, said the results will be used to support its ongoing scoping study, scheduled for completion in June, and show potential to generate a high-quality bauxite product.

Its shares soared 17% in recent trading on Tuesday.