Hydrochloric Acid Leaching Study of Rare Earth Elements from Moroccan Phosphate

Table 5

Experimental design and result.

No. of experiments	X1: HCl (%)	X2: temperature (°C)	X3: stirring (rpm)	X4: S/L ratio (%)	X5: time (min)	Y: response (ppm)
1	13	25	100	20	60	3.870
2	23	25	100	20	30	8.932
3	12	65	100	20	30	4.801
4	23	65	100	20	60	13.970
5	13	25	300	20	30	3.104
6	23	25	300	20	60	11.452
7	13	65	300	20	60	7.523
8	23	65	300	20	30	10.134
9	13	25	100	50	30	2.055
10	23	25	100	50	60	4.833
11	13	65	100	50	60	2.144
12	23	65	100	50	30	4.343
13	13	25	300	50	60	2.020
14	23	25	300	50	30	5.343
15	13	65	300	50	30	2.430
16	23	65	300	50	60	6.343
17	18	45	200	35	45	2.903
18	18	45	200	35	45	3.010
19	18	45	200	35	45	3.001
20	18	45	200	35	45	3.020
21	18	45	200	35	45	3.890