Note 14 - Capital Stock - Warrants Outstanding and Exercisable (Details) - $ / shares	12 Months Ended
	Jul. 31, 2022	Jul. 31, 2021	Jul. 31, 2020	Jul. 31, 2019
Weighted Average Exercise Price (in dollars per share)	$ 1.92	$ 1.90	$ 2.03	$ 1.94
Number of Warrants Outstanding (in shares)	3,615,454	5,387,323	7,721,981	19,443,910
Weighted Average Remaining Contractual Life (Year)	3 months 29 days
Warrants 1 [Member]
Number of Warrants Outstanding (in shares)	3,408,636
Weighted Average Remaining Contractual Life (Year)	1 month 24 days
Warrants 2 [Member]
Number of Warrants Outstanding (in shares)	25,000
Weighted Average Remaining Contractual Life (Year)	9 months 18 days
Warrants 3 [Member]
Number of Warrants Outstanding (in shares)	181,818
Weighted Average Remaining Contractual Life (Year)	3 years 8 months 4 days