Rare earths leaching from Philippine phosphogypsum using Taguchi method, regression, and artificial neural network analysis

Table 3 Experimental matrix and the resulting La, Ce, Nd, Y, and TREE leaching efficiencies (%)

Te st number	C (%)	T (°C )	t (mins)	S/L ratio (g mL⁻¹)	La (%)	Ce (%)	Nd (%)	Y (%)	TREE (%)
1	1	28	120	1:5	16.5 ± 1.1	11.9 ± 1.2	12.9 ± 1.4	13.7 ± 0.6	13.7 ± 0.9
2	2.5	28	120	1:5	30.8 ± 0.7	26.1 ± 0.9	26.5 ± 0.8	30.4 ± 0.8	28.4 ± 0.6
3	5	28	120	1:5	39.7 ± 2.1	35.8 ± 2.3	35.2 ± 2.0	40.3 ± 1.6	37.7 ± 1.9
4	10	28	120	1:5	58.7 ± 4.8	57.6 ± 5.0	52.7 ± 4.2	56.4 ± 3.7	55.9 ± 4.3
5	10	40	120	1:5	62.4 ± 0.7	61.3 ± 0.8	55.9 ± 0.8	58.5 ± 0.8	58.8 ± 0.8
6	10	50	120	1:5	74.6 ± 2.9	72.4 ± 2.5	70.6 ± 3.6	68.2 ± 2.5	71.0 ± 2.9
7	10	60	120	1:5	69.5 ± 5.5	67.6 ± 4.8	64.4 ± 7.1	63.2 ± 4.2	65.6 ± 5.5
8	10	70	120	1:5	64.8 ± 2.7	63.6 ± 2.3	58.4 ± 3.6	59.0 ± 1.9	60.8 ± 2.6
9	10	80	120	1:5	73.3 ± 5.9	70.9 ± 5.5	68.9 ± 7.0	66.1 ± 5.3	69.2 ± 6.0
10	10	50	5	1:5	57.7 ± 2.1	53.8 ± 2.3	49.5 ± 2.2	52.4 ± 1.4	52.9 ± 1.9
11	10	50	15	1:5	62.6 ± 0.2	58.7 ± 0.2	53.6 ± 1.0	56.2 ± 0.8	57.1 ± 0.5
12	10	50	30	1:5	63.0 ± 0.2	59.2 ± 0.5	53.9 ± 0.3	57.1 ± 0.8	57.6 ± 0.5
13	10	50	45	1:5	64.1 ± 0.3	60.4 ± 0.1	55.4 ± 0.3	58.5 ± 0.7	59.0 ± 0.3
14	10	50	60	1:5	63.9 ± 0.9	60.4 ± 0.7	55.3 ± 1.3	57.6 ± 0.8	58.7 ± 0.8
15	10	50	30	1:2	61.4 ± 0.8	59.4 ± 0.8	52.5 ± 0.9	57.5 ± 0.5	57.2 ± 0.7
16	10	50	30	1:3	63.9 ± 0.8	61.7 ± 0.9	55.1 ± 0.6	59.9 ± 1.1	59.6 ± 0.8
17	10	50	30	1:4	64.0 ± 0.2	62.0 ± 0.2	55.5 ± 0.3	59.8 ± 0.6	59.7 ± 0.1
18	10	50	30	1:10	65.5 ± 0.5	63.4 ± 0.4	57.0 ± 0.4	60.8 ± 0.7	61.1 ± 0.5