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The International Journal of Life Cycle Assessment

, Volume 23, Issue 10, pp 1928–1939 | Cite as

Life cycle energy use and CO2 emissions of small-scale gold mining and refining processes in the Philippines

  • Marie Chela B. Cenia
  • Mili-Ann M. Tamayao
  • Virginia J. Soriano
  • Kristine Mae C. Gotera
  • Benette P. Custodio
CARBON FOOTPRINTING
  • 167 Downloads

Abstract

Purpose

Gold is one of the most significant metals in the world, with use in various sectors including the electronic, health, and fashion industries. The Philippines has the world’s third largest known Au deposits and is ranked 20th in global gold production. Of the country’s annual production, about 80% is from the small-scale gold mining (SSGM) sector. This work estimates the first location-specific life cycle energy use and CO2 emissions of SSGM establishments in the Philippines.

Methods

Process-based LCA was used with functional unit of 100 g Au and observed data from 2010 to 2011 for mining, comminution, recovery, and refining. Four gold production paths were observed in the provinces of Benguet and Camarines Norte, namely, amalgamation, cyanidation with carbon-in-leach (CIL), cyanidation with leaching with zinc, and combination of amalgamation and cyanidation with CIL.

Results and discussion

It was estimated that 3–18 g of Au was extracted for every ton of ore within 57–159 man-hours from mining to refining. Energy use estimates ranged from 3501 to 67,325 MJ/100 g Au, while CO2 emission estimates ranged from 398 to 5340 kg CO2/100 g Au. The combination of amalgamation and cyanidation with CIL processes was the least energy and carbon intensive, while cyanidation with CIL process was the most intensive. Electricity use accounted for 95–100% of total emissions, except in cyanidation with CIL where kerosene accounts for 77% of the total. Since SSGMs contributed 80% of the 40 tons of Au produced in the Philippines in 2014, the SSGM energy use was estimated to be between 1120 and 21,544 TJ and the CO2 emissions to be between 129 and 1726 ktons CO2. Energy estimates are most sensitive to refining process yield and electrical equipment efficiency.

Conclusions

The estimated life cycle emissions rate for SSGM in the Philippines is lower than available estimates of large-scale mining. Notwithstanding, given the sector’s reliance on fossil fuels for its energy needs and the Philippines’ pledge to reduce its CO2 footprint by 70% in 2030, every effort to mitigate energy use and CO2 emission counts. Three main recommendations toward energy consumption and CO2 emissions reduction in SSGMs are proposed: (1) policy to promote technologies that are energy-efficient and processes that maximize gold process yield, (2) effective Minahang Bayan (SSGM mining zone mandated by law) implementation to ensure use of higher-grade ores, and (3) adoption of renewable energy in Minahang Bayans to promote energy independence and mitigate CO2 emissions.

Keywords

CO2 emissions Energy use Small-scale gold mining Sustainability 

Notes

Funding information

Funding for this work came from a grant from the Department of Science and Technology Engineering Research and Development for Technology BETTERMINE Project F and Scholarship Program.

Supplementary material

11367_2017_1425_MOESM1_ESM.docx (371 kb)
ESM 1 (DOCX 371 kb)

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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2017

Authors and Affiliations

  1. 1.Environmental Engineering Program, National Graduate School of EngineeringUniversity of the PhilippinesQuezon CityPhilippines
  2. 2.Department of Industrial Engineering and Operations Research, College of EngineeringUniversity of the PhilippinesQuezon CityPhilippines
  3. 3.Energy Engineering Program, National Graduate School of EngineeringUniversity of the PhilippinesQuezon CityPhilippines
  4. 4.Mineral Extraction and Refining for Sustainability (MINERS) Program, Project G, College of EngineeringUniversity of the PhilippinesQuezon CityPhilippines

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