Process

Lead sulphide concentrates are sintered at high temperature into a lump form or sinter. Sulphur is oxidised to sulphur dioxide in a gas stream that is cleaned and processed to make sulphuric acid.  The sinter and coke are charged to a lead blast furnace that produces a crude lead bullion and slag and the bullion is then refined to remove impurities including copper, arsenic, antimony, bismuth, silver and gold.  Metallic copper is then produced through leaching, solvent extraction and electrowinning. Silver and gold are produced as refined and semi-refined products, respectively.  The blast furnace slag is fumed to recover zinc and lead as impure oxides. These oxides are then processed by leaching, solution purification and electrowinning to make market zinc metal, in a similar manner to the RLE process.

Operations

Although historically the majority of concentrates were sourced from the Broken Hill and Endeavour mines, the reduced availability of Broken Hill concentrates in recent years has led to an increase in supply from other sources, most notably Cannington, Rosebery and Century.  Currently, Port Pirie processes all of Rosebery's lead concentrates and a significant proportion of Century's lead concentrates.  In addition to processing lead concentrates, Port Pirie also processes around 110,000 tonnes of by-product residues which it sources from Hobart and from its own historic stockpiles.  The residues provide Port Pirie with an almost costless source of feedstock which contains over 17% zinc.  Currently, Port Pirie's capacity limits the quantity of residues it can treat and the excess received from Hobart is stockpiled on site. Plans to increase Hobart's proportion of Century concentrate are key to ensuring Port Pirie is able both to treat Hobart's residues and meet the EPA's target to eliminate all on site residue stockpiles by 2020.

Production

Following an improvement program that targeted plant availability and operating efficiency, Port Pirie's lead production capacity was approximately 270,000 tonnes peryear. The closure of the Cockle Creek smelter in 2003, however, removed Cockle Creek bullion as a feedstock, effectively limiting the plant capacity to 245,000 tonnes. Zinifex is currently evaluating a number of options to increase the blast furnace capacity.   The current zinc production facilities have a capacity of 43,000 tonnes per year of SHG and zinc alloys, which is fully utilised. Port Pirie produces approximately 95,000 tonnes per year of sulphuric acid, which is sold to a global acid marketing company under a long-term contract.

Environmental Management

Port Pirie works closely with and supports the local Environmental Health Centre to minimise potential health impacts of metals in the community. Community lead in blood levels in children are now at less than half the level that they were in the mid 1980's. Our aim is to progressively reduce lead in blood levels such that ultimately all children meet the national goal of 10 micrograms per decilitre.

August 30, 2021 - The owners of Port Pirie's lead smelter have been fined $35,000 for a series of failures that led to 700 litres of "toxic" sulphuric acid leaking from the plant into waterways and mangroves near the town.  Nyrstar caused material environmental harm by polluting the environment through toxic waste leakage between January 31 and February 2, 2019 — the extent of that harm could not be quantified.  The Environment, Resources and Development Court previously heard the company did not respond for about eight hours as it made "a wrong assumption" that the leak only contained weak acid.  Judge Paul Muscat said the case was not a "flagrant disregard" by Nyrstar and sat at the lower end of the scale.  "An incident of this general nature was not entirely unforeseeable and effective mechanisms to prevent it could — and should — have been implemented," he said.  "The incident was not caused by a single error but a combination of small failures in processes and human error that led to environment harm.  "These systems and processes were clearly insufficiently designed and not implemented to the required standard.  "The harm in this case is to be limited to potential environmental harm that is not trivial."  The acid leak occurred when the systems the Nyrstar had in place to prevent a spillage "failed", with sulphuric acid corroding a wrongly installed valve on the very system designed to safeguard against leakage.  It led to "a slug" of acid filtering into the waterways.  The Environment Protection Authority previously — in seeking a penalty of up to $120,000 — told the court the leak increased the presence of heavy metals in the natural and manmade waterways that were toxic to aquatic life, but it could not be "conclusively proven" that the acid leak was responsible for killing fish, as there was an algal bloom present at the same time.  A spokesperson for Nyrstar said quick action was taken after the spill to replace the affected valve.  "Nyrstar also made adjustments and upgrades to ancillary equipment to reduce the likelihood of further spills, and improved its monitoring and response processes to better manage potential spills," the spokesperson said.  "Nyrstar has fully cooperated from the outset with the EPA investigation and subsequent court proceedings.  "In addition, it undertook its own investigation and shared its data and findings with the EPA.   "Since the date of the spill, Nystar's new management has driven further significant environment- and safety-related upgrades at the Port Pirie site."   Judge Muscat gave Nyrstar credit for addressing the inefficiencies in its systems.  The company has also been ordered to pay costs of $5,000. 

March 25, 2020 - South Australia's environmental watchdog will prosecute a Belgian company over allegations 700 litres of acid leaked from its Port Pirie lead smelter into a creek.  The Environment Protection Authority (EPA) will prosecute Belgium-based Nyrstar Port Pirie Pty Ltd in the Environment, Resources and Development (ERD) Court for allegedly causing serious environmental harm.  The EPA will allege Nyrstar polluted the environment by "discharging, or failing to prevent the discharge of, about 700 litres of sulphuric acid" from its smelter into First Creek between January 31 and February 3 last year.  "Potential environmental harm was caused by polluting the environment and creating harmful conditions for fish and other plant and animal life in the creek," the EPA said in a statement.  In a statement, Nyrstar confirmed the EPA had issued it with a summons to appear in court.  "Nyrstar does not intend to provide ongoing commentary in relation to this matter given it involves legal proceedings."  In October 2019, ABC News questioned the company over allegations mass fish deaths had occurred in a breeding ground near the factory site.  At the time, Nyrstar said "the incident occurred following the failure of a valve and ultimately resulted in a discharge into the water course".  Documents from the EPA, released under Freedom of Information, alleged sulfuric acid leaked from Nyrstar's factory into Port Pirie's First Creek on January 31.  The EPA refused to release a summary of the incident, however February briefings to South Australia's Primary Industries Minister Tim Whetstone said "localised fish kills" had occurred in mangroves, with State Government investigators unable to assess the damage for at least five days after the spill.  Parliamentary briefing notes were prepared for ministers and media statements were prepared, but no public announcement was made.  Local net fisherman David Wilkes, who reported the alleged January sulfuric acid leak, said the smelter was important to the town, but called for greater transparency to ensure the environment was kept clean.  He said alleged leaks had been the subject of discussion in the community, but there had been no formal notification from the State Government or Nyrstar.  "When these sorts of things happen, I think it's the responsibility of the smelter to let the public know exactly what's going on, what the consequences are and what remedies have been made to fix the situation."