Thank you. Good morning and good afternoon, everyone, and thank you for participating in another Nexa's earnings conference call. Today, we will be talking about our results for the third quarter of 2019.
Please, let's move to Slide 3 where we will begin our presentation. Here, we present some of the main highlights of the quarter. Beginning with our segment performance, our mining operations were solid. Zinc production was 97,000 tons, up 80% (sic) [ 8% ] compared with third quarter of 2018, driven by Cerro Lindo and Vazante growth. Regarding our smelting segment, production was affected by technical issues in the purification process in Três Marias smelter during September. As a result, metallic zinc sales in third quarter of 2019 decreased by 0.8% from last year. Compared to second quarter 2019, however, sales volume was at 1.2%. It was affected by the 6% volume increase in Cajamarquilla, driven by higher export sales.
Moving to our financials. Adjusted EBITDA was $58 million in third quarter compared with $120 million last year. Lower average LME prices and changes in market prices in respect of quotation period adjustments had a negative impact of $37 million. We also had a temporary increase in G&A costs related to operational efficiency initiatives that I will comment later in our presentation. Liquidity remains strong, and we end the quarter with a leverage of 1.4x. Despite the challenging pricing scenario, operating cash flow was positive in $105 million, driven by working capital improvement. Free cash flow was also positive in $35 million. In third quarter, we recognized a non-cash interim loss of $142 million in Cerro Pasco cash-generating unit primarily driven by lack of mine production. As a result of the above-mentioned factors, net loss was $171 million in the third quarter.
Regarding guidance, we've revised our zinc production range downwards, due to an equipment failure in Vazante. Equipment repair should last about 30 days, and we expect a production loss of 8,000 to 10,000 tons of zinc in concentrates. We are maintaining the production forecast for the other metals.
In respect of investments, we have revised our capital allocation strategy, and we are prioritizing operation investments that will contribute, not only in the short term, but it will also sustain our long-term growth. As a consequence, project development expenses were reduced to $35 million. Regarding our main project, construction works in Aripuanã continued to advance with 66% of the total CapEx project committed and 18% physical progress. We also closed the Karmin 30% state acquisition on October 3.
Moving to the next slide, we'll talk about market fundamentals. In third quarter, average zinc price was $2,348 per ton, down 7.4% and 15% compared to third quarter of 2019 and second quarter of 2019 respectively. Despite a modest recovery by mid-September, short-term prices were still affected by the uncertainties regarding global economy performance and its impact on sectors growth. Refined zinc stock worldwide remained at very low levels. There was an outflow in both LME and Shanghai Futures Exchange stocks during the quarter and stock forecast for year-end is still below 10 days of consumption. The smelting production in China remain below initial estimates. And as a result, treatment charges continue to be at high levels reaching almost $300 per ton of concentrate in September. Copper and lead prices also dropped during the quarter impacted by the macro scenario other than market fundamentals.
Let's please turn to Page 5, where we will comment on our third quarter consolidated results. Beginning with the first part on your left, zinc production of 97,000 tons increased by 80% (sic) [ 8% ] compared to third quarter of 2018 explained by higher production in Cerro Lindo and Vazante mines. Copper production followed the same trend and increased by 3% year-on-year primarily driven by a 4% increase in Cerro Lindo. In third quarter, zinc-equivalent metal production totaled 148,000 tons. That's 80% (sic) [ 8% ] and 9% compared to third quarter of 2018 and previous quarter respectively. This increase was mainly driven by better metals average rates. In respect to our smelting segment, metallic zinc sales volume of 149,000 tons was down around 1% versus the same period a year ago. Cajamarquilla increase was offset by lower production volume in Três Marias, which faced technical issues in its purification process during September. Compared to the second quarter of 2019, sales volume increased by 1%.
The planned shutdown at Cajamarquilla smelter to implement the Jarosite process conversion has been delayed. The heat exchanger and the replacement of chips had a different specification from what was contracted. As a result, production will not be reduced and smelter recovery rate should continue to improve. The conversion to the Jarosite process is now expected to be completed in the first half of 2020.
On the following graph, adjusted EBITDA was $58 million compared with $120 million in third quarter of 2018.
Please let's move to Slide 6 where we will discuss EBITDA in more detail. Compared to third quarter of 2018, adjusted EBITDA decreased 52% to $58 million. This performance is primarily explained by a negative variation of $37 million due to lower LME prices and changes in market prices in respect of quotation period adjustments. An increase in operational cost, driven by higher maintenance and personnel expenses and the temporary increase in G&A expenses of $16 million related to operational efficiency initiatives, which have already a positive impact on our operations. And before I continue, I would like to take the opportunity to discuss about those initiatives that I have just mentioned. First of all, it's important to clarify, this is not a cost reduction problem only, it's bigger than that. We, and when I say we, I'm talking about all Nexa's employees, we are putting our efforts to analyze all our internal processes in order to capture opportunities. And not only short term, but consistently improve our business model in the long run. We still don't have a number of potential gains that we could share, but we can highlight some of the achievements we already had in the quarter.
In Cerro Lindo, for example, we improved our mining recovery as a result of more precise drilling and blasting activities. In Cajamarquilla, we've been improving our global recovery and, as a consequence, our zinc metal production has increased. We signed a new energy [ job ] in Peru, beginning in January 2020 with the potential gain of up $50 million. We also signed a new agreement in Furnas in Brazil, which provides us excess energy that we intend to use in Aripuanã. We will maintain our efforts to build a differentiated, sustainable and cost-efficient business model generating value for our stakeholders.
Please move to Slide 7, where we will continue our presentation. On this slide, I will comment on our mining segment performance. Net revenue amounted to $248 million, slightly down year-over-year, as production increase was offset by lower average metal prices. EBITDA was $33 million compared with $65 million in third quarter of 2018. This performance was mainly explained by lower LME prices, higher operating costs and an increase in G&A expenses due to change in corporate expenses allocation to the mining segment compared to last year. In third quarter of 2019, cash cost net of by-product was up 22% compared to last year. Compared to second quarter, however, mining cash cost improved by 12% due to better volumes and higher by-product credits.
Let's please move on to Slide 8, where we present our smelting performance. In third quarter of 2019, net revenue was $442 million down 8% compared to last year, explained by lower volume and lower price. EBITDA for the segment was $25 million compared with $57 million in 2018. The decrease was primarily driven by a negative variation of $25 million due to lower LME price and changes in market price in respect of quotation period adjustments. Smelting cash cost was $0.99 per pound, down 11% from third quarter of 2018. Different from our mining segment, market-related factors had a positive contribution of $0.10 per pound. Compared to second quarter of 2019, cash cost decreased by 5% primarily due to lower LME prices.
Please move to Slide 9. Regarding our debt profile and cash position, we continue to report a healthy balance sheet with extended debt profile and low leverage. And maintained that breakdown characteristics by certain currency, as seen on the lower left side of the page. According to our liquidity strategy and taking advantage of the current market conditions, in October 2019, Nexa contracted a revolving credit line of $300 million.
We're also doing the 5-year export credit note agreement in the amount of $19 million. As a result, our current available liquidity is approximately $1.2 billion. As of September 3, the average maturity of our total debt was 5.4 years. On the right side, we've seen a debt decrease as a result of a slightly reduction in our gross debt. Our leverage, measured by duration and net debt/adjusted EBITDA of the last 12 months stood at 1.4x compared with 1.3x into this quarter as a result of lower EBITDA.
Please let's move to Slide 10. On this slide, we present Nexa's free cash flow generation. Starting from our $58 million adjusted EBITDA, we had a positive change in working capital of $88 million, driven primarily by the withholding tax payment normalization, inventory decrease and improved receivable sales also contributed to working capital gains. We spent $53 million in sustaining CapEx and interest paid. As a result, cash flow before expansion project was positive $88 million. Nonsustaining CapEx, including Aripuanã and regional projects, amounted to $62 million. Additionally, we increased our cash position below 90 days, which result in an increase of $35 million in our investment position.
On top of this noncash event, it affected our free cash flow in the period. As a result of the factors that we have just discussed, free cash flow was positive $36 million.
Please let's move to Page 11. On this slide, we will comment now on our 2019 guidance. As already disclosed to the market, we experienced an equipment failure at Vazante mine, and its repair is expected to last about 30 days. During this period, Vazante mine should operate at 30% of its nominal capacity. And as a result, we have reduced our zinc production guidance by 15,000 tons. Production guidance for the other metals remains unchanged. Smelting sales guidance is also unchanged. Production decrease in Três Marias in the third quarter should be compensated by higher production in Cajamarquilla, as the planned shutdown to implement the Jarosite process conversion was postponed to next year as already mentioned.
Let's move now to next slide. On Slide 12, we will comment on our mineral exploration and project development investments. In the third quarter, mineral exploration expenses were $22 million, mainly related to greenfield and brownfield explorations. Project development expenses amounted to $10 million, including $5 million in FEL1 and FEL2 project studies. For the year, our mineral exploration guidance of $75 million remains unchanged, while project development was revised downwards to $35 million. In respect to capital expenditure, we invested $104 million in the quarter, of which 56% related to expansion projects including Aripuanã. Capex guidance for the year remains unchanged.
Let's move on to the next page. Construction works in Aripuanã continued to advance and by the end of third quarter, 18% of physical progress was achieved in line with the construction schedule. In third quarter, we concluded addition of the Link ramp-up tunnel. Infrastructure and earthworks projects continue to progress as expected, including main roads providing access to the site. Around 66% of the total project CapEx has been already committed, and we maintain our investment guidance of $140 million for 2019.
In August, Nexa announced the acquisition of Karmin and the Aripuanã zinc project for $70 million. The transaction was concluded in October and now Nexa and its affiliates own 100% of the project. The acquisition reinforces not only our commitment to the project, but the perspective to increase shareholders' return to potential life of mine expansion and operational and tax synergies with our operations in Brazil. During the third quarter of 2019, we also began the training program for future miners and plant professionals as well as the refurbishment of the local school.
Moving to our final slide. As we have been discussing over the past 2 years, we expect to generate value through the performance of our operations and execution of our growth projects. Our balance sheet was prepared to support our investment cycle, even in an adverse macro scenario. Our liquidity remains strong, and we have just reinforced it with the new revolving credit facility. We have revised our short-term capital allocation strategy prioritizing operational efficiency initiatives without jeopardizing our long-term growth. The construction of Aripuanã project continue to advance as expected. Mineral exploration activities also continue to progress in efforts to increase reserves and resources, ensuring long-term sustainability.
In respect to our current operations, as previously mentioned, we've signed a new energy agreement, which should generate savings in Peru and Brazil, starting January 2020. And in order to keep market update in terms of our potential value creation, we plan on filing updated technical reports on Hilarión, Cerro Lindo and Magistral in the short term. Thank you all for your time and let's move on to the Q&A session.