Alberto Calderon
Analyst · RBC
Thank you, Stewart. Good afternoon, and thank you for joining us for this first quarter production update. We've had a good start of the year with another strong safety result and a good overall performance from the portfolio. In fact, this is the strongest first quarter performance from our operating assets this decade. That's down to greater consistency from most of our operations. In Brazil, both sides have shown significantly better performance with greater production control, Geita and Kibali were strong again and Obuasi's ramp-up remain on track.
We'll start where we always do with safety. We're proud of another strong performance as we work hard to keep our people safe in an often challenging operating environment. We continue to make steady progress on our journey to zero harm. Our total recordable injury frequency rate is well under half of the average to ICMM members. But we've never are complacent. In fact, we dedicate an increasing amount of time and resources to understanding the root cause of accidents and near misses in the workplace, and we realize we're only as good as our last injury-free day.
Production was up 2% year-on-year to 581,000 ounces driven by strong performances from a number of our key assets and in spite of the one in a thousand year rainfall event in Western Australia. This event caused a reduction in output or more accurately a postponement of about 15,000 ounces of production in Q1. Were it not for that, production would have been up more than 4%. The big movers in the portfolio were Cuiaba plus 55%; Serra Grande, plus 40%; Kibali, plus 19%; and Geita plus 16%. There were offsets, and we'll talk more about that [indiscernible] in from Siguiri and obviously, from our Australian operations. Importantly, we're well on track to achieve guidance we set out in February of 2024.
Most of our Tier 1 assets recorded a solid quarter starting with Geita, the production improvements was driven by higher volumes in grade. At Kibali, with a 19% gain, we saw increases in recovery grades and ore tonnes processed. The flooding at Tropicana interrupted power to the plant and cause mining to be suspended. I'll talk to the remedial steps there in a moment, but suffice to say production is back on track now that things have dried out.
Moving to the other two miles. We continue to drive full asset potential initiatives to enhance asset performance, Cuiaba recorded a strong quarter, producing 44,000 ounces from concentrate and 21,000 ounces from the gravity circuit. The same weather system that hit Tropicana had a lesser impact on Sunrise Dam, which otherwise had a very solid performance.
Siguiri production was hit by poor equipment availability and to a greater extent by a drop in metallurgical recoveries associated with highly carbonaceous ore from parts of Bidini pit. A new excavator and the decision to prioritize ore from alternative mining areas has held production bounce back after the quarter end with 22,000 ounces of attributable production in April. And across Serra Grande, we're very pleased to see the start of a turnaround with a 40% increase in production year-on-year.
Obuasi, the V30 reamer continues to do exactly what we expected. To recap, we're establishing conventional stopes with a much wider reamer head, which is overcoming a lot of the challenges which we saw in Q3 of last year. We're seeing better results with ore tonnes up 16% year-on-year and at similar levels of Q4. Production was slightly lower than year-on-year, which was in line with our plan and down simply to the lower grade areas in the mine plan. The important thing is we continue to see production for the year between 275,000 and 320,000 ounces with a back-end loaded profile and H2-loaded profile. The real prize for us this year will be the higher grade Block 10, which is now being opened up and will be available to mine in the second half. This underpins our plan annualized 360,000 ounces in Q3, reaching that level in Q3.
The underhand drift and fill trial is going well. This is the method that we'll use in very high-grade areas, which are increasingly associated with difficult ground conditions. We've mined and filled the first cup and tested the strength of the field from parallel drive, we're actually beginning this week to mine underneath that. We've also filled that parallel drive in a single pour with that field curing in 14 days.
Next slide, Phase 3 is that refurbishment and return to service of the KMS shaft and associated infrastructure. This will provide direct access to the very high-grade Block 11 and other areas. It will double our current underground materials handling capacity to around 12,000 tonnes per day. If you look at the Red block on this slide, it shows a significant advantage, we'll have when we can move waste, ore and other materials down the shaft with no congestion rather than transporting it via 12-kilometer decline. The added flexibility will be a significant benefit. We estimate completion by about the end of this year.
You will also note that this is important in the Orange outline Block 10, with grades around 8.3 grams per tonne, where we expect to roll out the underhand UHDF mining method, but also we expect to be reaching through conventional stoping in Q3 this Block 10.
The next key project milestones include completing and commissioning the vent shaft rail system and new pump stations as well as ore passes between the upper mine and rail transport level. Good progress is being made to clear mud between 5,100 level and the shaft bottom.
Brazil. Brazil has seen an enormous amount of work down over the past 9 months under the new leadership that we put in place. It is an extraordinary turnaround. We've done a root and branch clean up to the old structure, ensuring accountability is properly located. Waste is being stripped out and capital expenditures scrub. We've narrowed the focus of the team by placing the heavily loss-making CdS on care and maintenance last year. And the full potential program is working as designed.
Cuiaba has bounced back strongly after switching to a concentrate operation last year. Grades are up, volumes are up, all that's helped us post a 55% increase in production. Importantly, planning is well advanced to restart the Queiroz plant, which will be another quantum leap in performance. Serra Grande has also come to the table with a 40% increase in production. The focus for us now will be to ensure that this trajectory can be maintained. You will recall this time last year, our group free cash flow was negative $161 million primarily driven by the challenges in our Brazil operations. We have seen a complete turnaround and look forward to sharing the financial results of this region when we report the half year in the coming months.
We aren't, as we said, presenting full financials. But nevertheless, in a preview using the metric that we have heard has become very fashionable through some of our competitors' free cash flow before working capital it would be -- would have 3 digits in Q1, and it's going to be quite strong for the rest of the year. Also, after working capital, we also would have a positive free cash flow in the first quarter of the year.
Slide 10, operational focus areas. Our focus on recovering from the challenges during the quarter. You can see from the picture here, the extent of the flooding that hit our operations during the quarter. 350 millimeters of rain or almost half the annual rainfall fell in under 3 days. Access to roads were out of action, power was interrupted and mining was suspended. Since then, remedial work to restart operations was successfully completed and mining and processing has since restarted. Whilst gold production was impacted in Q1 and consequently, for the first half, we expect to recover a significant portion of this production in the second half.
I spoke about the challenges we saw at Siguiri in Q1, low digger availabilities and a big drop in recoverers. A new digger is being delivered to site and plant recovery have stabilized and improved back to normal levels. We've taken Bidini ore out of the plant pit and have replaced it with ore from a series of other pits. Thankfully, Siguiri less with multiple ore sources.
In the meantime, our technical team is doing additional test work to improve the recoveries of the carbonaceous Bidini ore. So in sum, in Siguiri, we have the -- right now, the recoveries up to the mid-80s. We have moved to owner mining operated and now we have improve the availabilities. And hence, we're seeing -- we saw a very good month in April and seeing a very good month in May too.
Nevada updates. Moving to the [ Nevada ], where the permitting this underway at North Bullfrog, we continue to anticipate the record of decision next year. In the meantime, detailed engineering is on track. We've started the PFS at expanded silicon, which is focused on the Merlin high-grade area with mining, processing and infrastructure trade-off studies. We are targeting completion in H2 of next year.
As we've said before. The project team has also identified potential for some early cash generating potential in the Southern extent of the lease and is evaluating those. The sterling project is a small early-stage project that plans to reprocess 1.5 million tonnes of previously mined ore and mined 42 million total tonnes, 13.4 million ore tonnes using open-pit heap leach methods. The project would produce around 200,000 ounces at an all-in sustaining cost of $870 an ounce.
There are existing permits in place that will be in modification, which will be the critical path for production. It is estimated to produce first gold in 2028. Currently, metallurgical test work is underway to control recovery and CapEx assumptions that we use. I look forward to giving you a further update on Nevada in August.
In close, we remain focused on making more improvements and are delivering more consistent results in line with the targets that we have set out. We have achieved key milestones over this period, notwithstanding the challenges that we have faced. Brazil is well on its way to a stronger 2024 performance, almost and imagine more from where it was this time last year.
[indiscernible] really have a robust plan that we're executing at Obuasi and expect Tropicana to achieve its production targets by year-end. Our Q1 assets are performing well with more improvements in the pipeline. We're optimizing our important Tier 2 mines. We're focused on improving operating and capital efficiencies, as we continue to improve our cost competitiveness.
We are again on track to achieve our guidance in all metrics. And while this call is a production and operating update, we are confident in the delivery of our cash costs and our all-in sustaining, our asset cost at the lowest end of our full year guidance and we are ensuring that high gold practices flow through the free cash flow, net taxes and royalties.
In other words, even though we are facing, like all of our competitors, around a 5% inflation, we have basically managed to compensate it almost completely with our full asset potential program. We have already seen the guidance of our competitors. If you remember 3 years ago on cash costs, we're about $300 an ounce away, and we set ourselves to target to narrow that to a 2-digit level. Well, if we deliver like we believe, to the lowest end of the guidance, we would be between $30 and $95 an ounce of the two largest gold companies in the world.
More importantly, for 3 years in a row, we have met the guidance on production and cash cost, probably the only company. And that's how we have basically closed almost between 70% and 90% of the gap that we have. Thank you.
We open to questions now.