Note 13 - Capital Stock - Warrants Outstanding and Exercisable (Details) - $ / shares	12 Months Ended
	Jul. 31, 2021	Jul. 31, 2020	Jul. 31, 2019
Weighted Average Exercise Price (in dollars per share)	$ 1.90	$ 2.03	$ 1.94
Number of Warrants Outstanding (in shares)	5,387,323	7,721,981	19,443,910
Weighted Average Remaining Contractual Life (Year)	1 year 94 days
Warrants 1 [Member]
Weighted Average Exercise Price (in dollars per share)	$ 2.30
Number of Warrants Outstanding (in shares)	271,546
Weighted Average Remaining Contractual Life (Year)	1 year 7 days
Expiry Date	Aug. 09, 2022
Warrants 2 [Member]
Weighted Average Exercise Price (in dollars per share)	$ 1.64
Number of Warrants Outstanding (in shares)	25,000
Weighted Average Remaining Contractual Life (Year)	1 year 292 days
Expiry Date	May 21, 2023
Warrants 3 [Member]
Weighted Average Exercise Price (in dollars per share)	$ 1.80
Number of Warrants Outstanding (in shares)	4,908,959
Weighted Average Remaining Contractual Life (Year)	1 year 54 days
Expiry Date	Sep. 23, 2022
Warrants 4 [Member]
Weighted Average Exercise Price (in dollars per share)	$ 1.83
Number of Warrants Outstanding (in shares)	181,818
Weighted Average Remaining Contractual Life (Year)	4 years 248 days
Expiry Date	Apr. 05, 2026