Cover Story
Noracid: A decade of progress
By: April Smith, Editor, Sulfuric Acid Today
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oracid is marking its ten-year anniversary manufacturing sulfuric acid at its plant in Mejillones, Chile. Over the last decade, the facility has been stalwart in supplying local copper mining operations with the necessary ingredient for separating metal from ore. The plant has also been a model for longevity and plant availability. Recently Noracid’s managers, together with representatives from the plant’s designer, Metso Outotec, reviewed the facility’s performance and cataloged its operational statistics. They reflected on the how the design and maintenance practices have driven the plant’s success; and consider what needs to happen next to keep the facility performing optimally in the decade to come.
Noracid’s founding
Noracid was founded in 2007 to supply sulfuric acid to the key mining companies in the northern region of Chile. The plant came online in 2012 and was the country’s first large-scale producer of sulfuric acid, which it manufactures from the combustion of elemental sulfur. The plant’s proximity to the Mejillones port on the Pacific Ocean facilitates the movement of supplies and products. In addition to sulfuric acid, Noracid imports sulfur for use as feedstock and to sell to regional markets. The facility also generates electricity using heat released from the acid production process, and delivers it to the local power grid. Noracid began as a business consortium between Grupo Ultramar and Belfi. Grupo Ultramar provides marine port handling services, shipping, freight, and other logistics services. Belfi is an engineering and construction company; it provided the construction services that built the Noracid plant. Metso Outotec was granted the contract to design and supply the plant in 2009, and construction began the following year.
The products
Noracid consumes 240K tons per year of sulfur as feed stock to its acid operation. Bulk solid sulfur is also distributed to the iodine industry and boric acid manufacturing plants located in northern Chile and Argentina. On-site sulfur storage capacity is 100K tons. Sulfuric acid manufacturing capacity is 720,000 tons per year with storage capacity at the Mejillones terminal of 40,000 tons. From storage, 2,000 tons are transported daily, by trucks and trains, to mining operations in northern Chile. The plant also generates electricity by channeling the heat released from acid production into a steam turbine. The cogenSulfuric Acid Today • Spring/Summer 2022
Noracid marks ten years of service at its sulfuric acid plant in Mejillones, Chile.
eration process has a capacity of 26 MW. Of this, 9 MW is consumed at Noracid’s facilities while the surplus 17 MW is delivered to the local power network. Operating independently from the local power supply provides the key benefit of enabling continuous operation in the event of an outage in the public power network.
Milestones
Noracid has logged a strong performance history over the last ten years. “Their results in terms of availability and utilization of the plant are very high, particularly with regard to availability,” said Collin Bartlett, Director of Business Development at Metso Outotec. “Average availability is greater than
98.5 percent and they’ve had few unscheduled shutdowns.” From 2012 through 2021, unscheduled shutdowns averaged once per month for a period of 6 to 8 hours. And in all of 2020, unscheduled outages totaled only two days. These shutdowns were typically because of high vibrations of the sulfur burner, repairs to an expansion joint, or replacement of an acid recirculation pump. The plant’s operational timeline shows long stretches of continuous production. Since mid-2012, the plant has run for 24 to 36 months, pausing in between to carry out three main shutdowns. How did the plant achieve this success? Noracid and Metso Outotec credit two main factors: a robust design and an exacting maintenance protocol.
Design for longevity
Converter section (foreground) with sulfur melting and covered sulfur storage (background).
In 2009 when the design phase began, the term “sustainable” was not the buzz word it is today. Yet Noracid’s vision, carried throughout the project, was rooted in sustainable principles. “From the beginning, Noracid focused on reliability and operational cost efficiency,” said Bartlett, “and they have been willing to consider incrementally higher capital cost to reduce operating costs over the lifecycle of the plant.”
A few of the ways in which these principles manifested was in a design that maximized electricity generation as well as minimized overall water consumption. For the electricity piece, the facility integrated a steam turbine, which has consistently powered the entire operation, while also supplying 17 MW/year to the local power grid. In terms of water usage, a plan was formed to minimize both water consumption and energy use. Rather than implementing a water-based acid cooling system, which is standard for the industry, Metso Outotec designed an airbased cooling system instead. A water-based system would require desalinating the water before using it in the cooling process and then draining warmed effluent water into the Bay of Mejillones. Since local regulations at the time limited temperature increases in the bay, cooling by air made much better sense. “It was a fairly unique solution in the acid industry,” said Hannes Storch, Vice President at Metso Outotec. There was ample space on site for the cooling system, plus powering it from the facility’s own electricity supply provided an extra degree of plant independence. Planning for long-haul efficiency also meant the design would be capable of meeting current and future SO2 emission standards. Sustainable sulfur storage was another PAGE 7
