Environmental assessment of a Palette Modular Device for gold recovery from PVD

Figures & data

Figure 1. (a) A prototypal PMD installed in a vacuum chamber. (b) CAD model of the PMD system.

Figure 2. (a) Employment of sonicator during etching. (b) Gold recovered from etching phase.

Figure 3. Boundaries for recovery by PMD.

Table 1. Inventory of the first recovery scenario.

Sandblasting		Etching (acetone) sonicator		Palette regeneration
Input		Input		Input
Sand SiO2	1 kg	Acetone	2.370 kg	Cleaned palettes	1 m^2
Energy	27.3 MJ	Energy	1.650 MJ	Polymer	0.242 kg
		Polymer	0.042 kg
Output		Output		Output
Product		Product		Product
Cleaned screen	1 m^2	Cleaned palette	1 m^2	Regenerated palettes	1 m^2
Contaminated sand	1.040 kg	Gold	0.035 kg
Emissions		Emissions		Emissions
CO2	3.276 kg	CO2	0.197 kg	Dimethyl ether vapours	0.100 kg
PM10	0.013 kg	Acetone vapours	1.661 kg	Acetone vapours	0.100 kg
PM2.5	0.001 kg	Acetone-polymer	0.753 kg	Naphtha	0.001 kg

Table 2. Inventory of the second recovery scenario.

Sandblasting		Etching (acetone) – sonicator		Palette regeneration
Input		Input		Input
Sand SiO2	1 kg	Acetone	0.949 kg	Cleaned palettes	1 m^2
Energy	27.3 MJ	Energy	1.520 MJ	Polymer	0.242 kg
		Polymer	0.041 kg
Output		Output		Output
Product		Product		Product
Cleaned screen	1 m^2	Cleaned palette	1 m^2	Regenerated palettes	1 m^2
Contaminated sand	1.040 kg	Gold	0.035 kg
Emissions		Emissions		Emissions
CO2	3.276 kg	CO2	0.183 kg	Dimethyl ether vapours	0.100 kg
PM10	0.013 kg	Acetone vapours	0.047 kg	Acetone vapours	0.100 kg
PM2.5	0.001 kg	Acetone-polymer	0.943 kg	Naphtha	0.001 kg

Table 3. Inventory of the third recovery scenario.

Sandblasting		Etching (formic acid) –sonicator		Palette regeneration
Input		Input		Input
Sand SiO2	1 kg	Formic acid	1.440 kg	Cleaned palettes	1 m^2
Energy	27.3 MJ	Energy	1.560 MJ	Polymer	0.242 kg
		Polymer	0.041 kg
Output		Output		Output
Product		Product		Product
Cleaned screen	1 m^2	Cleaned palette	1 m^2	Regenerated palettes	1 m^2
Contaminated sand	1.040 kg	Gold	0.035 kg
Emissions		Emissions		Emissions
CO2	3.276 kg	CO2	0.188 kg	Dimethyl ether vapours	0.100 kg
PM10	0.013 kg	Formic acid vapours	0.007 kg	Acetone vapours	0.100 kg
PM2.5	0.001 kg	Formic acid-polymer	1.474 kg	Naphtha	0.001 kg

Table 4. Characterization of environmental impact related to the first scenario.

Emission	Mass (kg)	GWP100 (kg CO2eq.)	HTP (kg 1,4-C6H4Cl2eq.)	POCP (kg C2H4eq.)
CO2	3.4730	3.4730
Acetone vapours	1.7610	0.8805	0.0170	0.3205
Dimethyl ether	0.1000	0.1000	<0.0001	0.0263
PM10 + PM2.5	0.0143		0.0117
Total		4.4535	0.0287	0.3468

Table 5. Characterization of environmental impact related to the second scenario.

Emission	Mass (kg)	GWP100 (kg CO2eq.)	HTP (kg 1,4-C6H4Cl2eq.)	POCP (kg C2H4eq.)
CO2	3.4587	3.4587
Acetone vapours	0.1470	0.0735	0.0014	0.0267
Dimethyl ether	0.1000	0.1000	<0.0001	0.0263
PM10+PM2.5	0.0143		0.0117
Total		3.6322	0.0131	0.0530

Table 6. Characterization of environmental impact related to the third scenario.

Emission	Mass (kg)	GWP100 (kg CO2eq.)	HTP (kg 1,4-C6H4Cl2eq.)	POCP (kg C2H4eq.)
CO2	3.464	3.464
Acetone vapours	0.100	0.050	0.0010	0.0182
Formic Acid	0.007	0.0350	<0.0001	<0.0001
Dimethyl ether	0.1000	0.1000	<0.0001	0.0263
PM10+PM2.5	0.0143		0.0117
Total		3.6490	0.0128	0.0445

Figure 4. Results in terms of GWP indicator.

Figure 5. Results in terms of HTP and POCP indicators.