Thank you, Menck. Good morning, and good evening, everyone. Please, let's move to Slide 8.
Beginning with the first chart on your left, zinc production of 62,000 tonnes decreased by 32% compared to second quarter of 2019. The solid performance of our mines in Brazil was offset by the mandatory suspension of our mines in Peru, resulting in an estimated decrease of 1.7 million tonnes in treated ore volume in the quarter. Copper production was also affected and decreased by 44% year-over-year, primarily driven by Cerro Lindo.
In respect to our Smelting segment, total zinc metal sales of 120,000 tonnes decreased 23% versus the same period a year ago, given the reduced operating rate in both Cajamarquilla and Juiz de Fora smelters as demand for all products was impacted by COVID-19. On the following graph, consolidated net revenue was $337 million compared with $613 million a year ago, reflecting the decline in volumes and lower base metal prices. The LME average prices for zinc, copper and lead were down by 29%, 12% and 11%, respectively compared to second quarter of 2019.
Turning to Slide 9. We will comment on our consolidated EBITDA. Adjusted EBITDA decreased 66% to $40 million in the second quarter. This performance was mainly driven by lower sales volumes with an impact of $36 million, a negative price effect of $69 million related to lower LME prices and changes in market prices in respect of quotation period adjustments, the decrease in by-product credits due to lower treated ore volume and LME prices, which were partially offset by lower operating costs and expenses, partially driven by lower production volumes, the reduction in exploration and project development expenses, and the decrease in corporate expenses. The U.S. dollar appreciation against Brazilian real had a positive impact of $14 million in the period.
Please let's move to Slide 10. We will discuss our Mining segment guidance. On this slide, we discuss guidance and mining operation results. The strong performance of Vazante and Morro Agudo mines was offset by the mandatory suspension in Peru. As a result, zinc production in the second quarter of 2020 decreased 32% to 62,000 tonnes, while zinc equivalent production decreased 39%. Cerro Lindo and El Porvenir resumed operations on May 11, gradually increasing their throughput. Ramp-up continued into Q3. Atacocha and San Gerardo open-pit mine restarted operation on June 8, while the higher-cost underground mine remains suspended. The scenario still requires caution as the number of COVID cases in Latin America have continued to increase. And although, the high level of uncertainty remains, we maintain our 2020 production guidance for all our metals. We assume there will be no additional suspensions, but we estimate we will continue to face restrictions in our operations due to adopted measures to combat COVID-19.
Regarding cash cost, in first half of 2020, mining cash cost averaged $0.45 per pound, below our annual estimate. This performance was mainly driven by the temporary decrease in Cerro Lindo and El Porvenir, as we did not incurring some operating costs due to the postponement of certain mining activities, following lower production volumes. As we expect to increase production in both mines compared to the first half of the year, we believe we will perform according to our estimated guidance. In order to have an appropriate comparison, please note that the cash cost presented for both Mining and Smelting segments do not include the cost of idleness in our operations.
Moving to the next slide. On Slide 11, we will discuss the Mining segment performance. In second quarter of 2020, adjusted EBITDA was $3 million compared to $44 million a year ago. This decrease was primarily driven by lower volumes due to the temporary suspension in Peru with a negative impact of $77 million, market-related factors with a negative variation impact of $13 million from lower LME prices and higher treatment charges, and lower byproduct credits, totaling $19 million. These negative effects were partially offset by the decrease in operating costs and mineral exploration and project development expenses.
Looking to the graph at the bottom right, we present the global cash cost curve for zinc. Despite the challenging scenario, we remain well positioned at the beginning of the third quartile of the cash cost curve.
Moving to the next slide. On Slide 12, we will discuss our Smelting segment operational results and guidance. Metal sales in the second quarter of 2020 were down 23% year-over-year, reflecting the reduced operating rate of our smelters, as already explained. Despite a total volume reduction, Três Marias smelter had another solid quarter. Zinc metal production of 45,000 tonnes increased by 11% compared to the same period of 2019. Cajamarquilla smelter also operated better than we estimated during the quarantine period and resumed full capacity in the beginning of June. Juiz de Fora smelter is also close to its full capacity in July. That said, we maintain our metal sales and cash cost guidance, assuming we operate at normal CapEx during the second half of the year.
Moving onto the Slide 13, we will discuss our smelting EBITDA for the quarter. Smelting EBITDA was $39 million, 47% lower year-over-year. The decrease was primarily driven by the negative net price effect of $59 million related to changes in market prices and $5 million from lower byproduct credits, $19 million negative variation from the reduction in volume, partially offset by the $11 million gain from higher TCs, and lower operating costs and corporate expenses.
The BRL devaluation also had a positive impact of $7 million. Looking to the graph at the bottom right, we present the global cash cost curve for zinc smelters and Nexa is positioned at the beginning of the second quartile of the curve.
I will now turn over the call to Tito who will continue our presentation. Tito, please.