ESG (Environmental, Social and Corporate Governance) is a non-financial evaluation of a company’s investment and commitment to operating in a socially responsible manner. ESG is one of the most important issues facing companies today across all industries.

Emissions Intensity in Zinc Production

Emissions intensity for zinc means the amount of greenhouse gas emitted for every tonne of zinc produced. It has become a critical measure in the race to achieve carbon neutrality.

On average, the production of zinc produces around 3.0t of CO2 per tonne of zinc. This is comparable to the production of copper, but the zinc industry is much smaller than the copper industry. To further put this into perspective, the average passenger vehicle emits around 4.5t of CO2 per year. Greenhouse gas emissions are categorised into three groups: scope 1, 2 and 3 emissions.

Scope 1 covers all direct greenhouse gas emissions a company produces from its owned or controlled sources, for example from running machinery and company-owned vehicles.

Scope 2 covers the indirect greenhouse gas emissions a company produces, for example from purchased electricity, steam, heating, and cooling.

Scope 3 includes all other indirect emissions, both upstream and downstream, which occur in a company’s value chain. Scope 3 emissions are much harder for a company to record and control, but they tend to make up the bulk of emissions for a company. Scope 3 emissions include things such as outsourced activities, including transportation and distribution, business trips and employee commuting, leased assets, processing and the use of sold products and waste disposal in operations.

Virtually all countries globally have signed up to the 2016 Paris Agreement to limit global warming to well below 2 degrees Celsius and preferably to 1.5 degrees Celsius compared to industrial levels. Companies have begun to set their own competitive carbon neutrality targets, in line with and improving on wider country targets.

 “Green” Zinc Production

Smelting/refining is an incredibly energy-intensive process, which historically has meant it is also a very carbon-intensive process. As companies strive to improve their renewable energy strategies and reduce emissions, producing zinc using entirely green energy and reducing greenhouse gas emissions to close to zero is increasingly becoming a popular strategy.

Nyrstar has been using 100% green electricity at its Budel smelter since January 2021, reducing emissions at the site by 97%, with plans to reduce the remaining 3% of emissions. The onsite Budel solar park has plans to double capacity, which would make it the Netherlands’ largest solar park and contribute not just to Nyrstar’s carbon reduction commitments but to that of the whole of the Netherlands.

Nyrstar is also investing EUR30m (US$33m) to develop a battery storage system at the Balen site in Belgium. This will allow it to produce as much zinc as possible when the Dutch electricity grid has a surplus of green energy, and to reduce production when there is a shortage.

The Townsville zinc refinery owned by Sun Metals, a subsidiary of Korea Zinc, is planned to become the first refinery in the world to produce green zinc, meaning zinc made entirely from renewable energy. In 2021, Ark Energy Corporation was established by Korea Zinc to decarbonise the energy supply of the group, starting with Sun Metals.

The site is already host to the largest integrated industrial used solar plant in Australia, which supplies around 25% of the energy needed to power the site, and the company has plans to add a renewable hydrogen production facility and a wind farm, which is set to provide approximately 64% of the energy required to run the refinery.

While these green energy projects are a good effort towards producing “green” zinc, to fully decarbonise the process requires the development of new technologies to replace the fossil fuel reducing agents currently used by smelters. Companies such as Boliden are putting significant money into R&D projects evaluating hydrogen and bio-based alternatives as reduction agents.

Innovative Solutions

The Odda zinc smelter in Norway is among the most climate-friendly in the world. One of the reasons for this is Boliden’s approach to hazardous waste management. A bedrock repository was first built in Odda in 1986 for the disposal of hazardous waste from smelting at both Odda and the lead smelting plant in Bergsöe. In 2014, the rock repository at Odda was extended with a further two rock cavities.

In 2021, Boliden began construction of a new leaching plant at the Rönnskär site. The plant will enable waste material that has been stored at the site since 1975 to be reprocessed. This should allow the 460kt of waste material currently held to be decreased to around 220kt, which will be stored in a deep underground repository located under the Rönnskär smelter plant. This is a globally unique solution as it is the only place in the world where a deep underground repository shares a site with a smelter. 

The San Juan de Nieva zinc smelter in northern Spain, owned by Glencore, is one of the leaders in minimising water consumption. Through the analysis of existing processes and research of alternative processes, the smelter succeeded in reducing its water consumption by nearly 20% from 2004 to 2020, despite increasing the volume of zinc produced by 8%.