Recovery of elemental sulfur from zinc concentrate direct leaching residue using atmospheric distillation: A pilot-scale experimental study

Figures & data

Figure 1. Schematic diagram of the experimental system.

Table 1. Experimental conditions

Experiments	Temperature (°C)	Feed amount	Operating mode
Set I	490	400, 810, 1,185, 1,606, 2,032 kg/batch	Batch
Set II	430, 460, 490	About 1,200 kg/batch	Batch
Set III	460	250 kg/h	Semibatch
Set IV	460	4 kg/min	Continuous

Figure 2. Pictures of DLR with (a) 9.42% and (b) 19.85% moisture content.

Table 2. Major chemical composition of DLR sample (w/%)

	Composition
	SiO2	Al2O3	Fe2O3	CaO	MgO	K2O	SO3	MnO	ZnO	PbO
Content (%)	5.27	0.68	9.06	0.24	0.29	0.23	74.75	0.47	6.64	1.25

Figure 3. XRD profiles of (a) DLR and (b) DC.

Figure 4. SEM and EDX analysis of (a) DLR and (b) DC.

Figure 5. TG and DTG curves of DLR.

Figure 6. TG and DSC curves of DLR.

Figure 7. Temperature variation and power consumption during the distillation process.

Figure 8. Sulfur recovery during the distillation process.

Table 3. Experimental results

	Set I					Set II		Set III	Set IV
Serial number	1	2	3	4	5	6	7	8	9
Set temperature (°C)	490	490	490	490	490	460	430	460	460
Feed amount (kg/batch)	400	810	1,185	1,606	2,032	1,200	1,198	250 (kg/h)	4 (kg/min)
Moisture content of DLR (%)	16.76	15.79	16.11	9.42	17.96	19.85	12.64	15.00	12.10
Dry basis elemental sulfur content of DLR (%)	60.35	55.35	55.52	45.53	53.98	55.78	54.38	61.37	63.27
Sulfur purity (%)	98.26	99.26	98.21	97.63	95.54	96.22	99.12	94.55	93.15
Actual sulfur yield (kg/batch)	178.8	311.7	481.2	571.1	779.0	456.1	468.8	74.7 (kg/h)	85.7 (kg/h)
Sulfur recovery rate (%)	89.00	82.55	93.37	86.23	86.57	85.01	82.38	51.32	55.80
Dry basis elemental sulfur content of DC (%)	8.08	8.35	8.15	9.02	10.57	9.37	12.53	9.95	10.23
Balance of elemental sulfur (%)	96.76	89.52	93.91	96.31	93.77	90.32	89.42	—	—
Power consumption per unit of sulfur yield for dry DLR (kwh/kg)	3.49	2.4	2.27	2.19	1.84	1.24	1.08	2.66	1.80
Power consumption per unit of dry DLR disposal (kwh/kg)	1.87	1.1	1.09	0.86	0.85	0.59	0.48	0.94	0.73
Distillation period (min)	210	240	300	420	540	300	360	—	—
Disposal capacity per day (kg DLR/day)	2,743	4,860	5,688	5,506	5,418	5,760	4,792	6,000	5,760