As a result of the impairment, the group reported an operating loss of R949.9million compared to an operating profit of R498.4m last year.
Diluted headline earnings per share declined to 91cents a share compared to last year’s 95c.
The group declared a final dividend of 18c a share, up from 15c compared to last year.
During the year, turnover increased to R11.5bn, up from R10.3bn on increased volume, higher US dollar rolling margins and a firmer rand aluminium price.
However, the group said this was marginally countered by a strengthening rand compared to the US dollar, which averaged 7c stronger for the year.
Chief executive Richard Jacob said despite the setback Hulamin rolled products delivered yet another improved year in increasing sales by 6percent to 228000 tons.
“Hulamin extrusions experienced a challenging year with lower sales and recorded a net loss. Local fabrication markets were particularly soft throughout the year, affecting Hulamin extrusions most severely,” Jacob said.
He added that the third consecutive year of record sales volumes from rolled products helped to offset the poorer performance of the company's extrusions division.
In the second half of the year the group saw a better performance as the rand weakened to R14.18 to the dollar as compared to R12.30 in the first half of the year. Jacob said the group achieved headline earnings per share of 78c in the second half compared to 13c in the first half.
“We benefited from a weaker rand in the second half, because we export some of our products and a stronger rand is not good for our business,” Jacob said.
The board has approved a share buy-back programme of R60m. Jacob said the buy-back programme would commence this month and was planned to run on an even monthly basis for 12 months.
Looking ahead, the group remained focused on continuing the improved operational, sales and manufacturing performance in 2019, while focusing on executing its growth plans.
“The direction that the rand takes in 2019 will continue to impact financial performance as a result of Hulamin’s large foreign currency sales exposure,” Jacob said.
He added that the local and international long-term outlook for aluminium beverage packaging demand had improved significantly since 2017.
“This follows the steps being taken by more than 16 major countries and cities to ban single-use plastics in packaging. As a result, a number of Hulamin customers are seeking larger volumes and longer-term can stock contracts on firmer prices,” Jacob said.