Primary Copper Smelting Example Mini-Project Problem Presentation Stephen Zemba

Copper Smelters (from web sources)

Interesting Facts About Copper Copper produced in 13 states, 60% in Arizona (EPA AP42) Bingham Canyon, Utah – largest excavation in world => Trace-level nutrient in humans, toxic to many aquatic species

Definitions New Source Performance Standards from 40 CFR 60 Definitions New Source Performance Standards from 40 CFR 60.160 (Subpart P) Primary copper smelter means any installation or any intermediate process engaged in the production of copper from copper sulfide ore concentrates through the use of pyrometallurgical techniques. Smelting means processing techniques for the melting of a copper sulfide ore concentrate or calcine charge leading to the formation of separate layers of molten slag, molten copper, and/or copper matte. Secondary smelting involves the extraction and purification of copper from secondary materials other than ore

Copper (Cu) Production Raw ore has 1% copper Enrichment by mechanical separation (grinding and floatation) to 15-35% Cu, 25% S “Smelting” entails: Roasting, Smelting, Refining, & Melting Most steps involve fuel use Figure at right from Lead Locating and Estimating document

Schematic of Flash Furnace

Emissions and Controls Primary emissions are SO2 and PM; lead is 0.1-0.4% PM (AP42) NSPS are 650 ppm SO2 and 50 mg/dscm PM Typical controls are sulfuric acid (SO2) production and electrostatic precipitation (PM)

Title V Permit Kennecott Utah Copper LLC No information in RACT/BACT/LAER Clearinghouse 2007 permit issued by Utah Division of Air Quality, approved by U.S. EPA Region 8 114 pages long! Covers the smelter and a sulfuric acid plant Explicitly covers 47 sources Many sections for 40 CFR 60 Conditions, monitoring, record-keeping, reporting 40 CFR 60 Subpart P limits are met or more stringent 50 mg/dscm for dryer is the same as the Subpart P NSPS Max opacity of 15% required instead of 20% SO2 effluent at 250 ppm max instead of 650 ppm

Other Emissions Data and Information Metal Percentage of particulate matter Size ranges in µm 0 to 2.5 2.5 to 10 0 to 30 Antimony 6 5.6 5.917 Arsenic 24 38 26.893 Bismuth 0.4 0.317 Cadmium 0.51 0.46 0.5 Chromium 0.014 0.017 0.015 Copper 3 2.4 2.876 Indium 0.023 0.018 Iron 0.29 0.313 Lead 18 16 17.587 Manganese 0.009 0.01 Molybdenum 0.1 0.134 0.107 Nickel 0.04 0.07 0.046 Silver 0.12 Tellurium 0.17 0.18 0.172 Tin 0.39 0.398 Vanadium 0.016 Zinc 4.2 4 4.159 Above: Converter diagram from Lead Locating and Estimating document Left: Table of PM composition from EPA Speciate program

Copper Smelters Example Summary Sheet Copper Production Copper is mined in 13 states in the western U.S. Raw ore has ~1% copper and must be extracted and purified Concentration is first enriched by mechanical separation (grinding and floatation) to 15-35% Cu, 25% S “Smelting” involves heating, melting, and separating the components of the ore A facility typically use roasting, smelting, refining, melting, and other processes Most steps involve fuel use; some reactions provide heat as well Copper Smelters Example Summary Sheet New Source Performance Standards (apply to effluent) Particulate matter (PM): 50 mg/dscm Sulfur dioxide (SO2): 0.065% No visible emissions > 20% opacity Continuous emissions monitoring and compliance for opacity (6-min) and SO2 (6-hr) Method 5 stack testing for PM SO2 on a dry basis Pollutant emissions and controls Main pollutants are Particulate matter (PM) and Sulfur dioxide (SO2) Emissions depend on the process (furnace type) and the ore quality PM includes trace levels of arsenic, antimony, cadmium, lead, selenium, and cobalt at trace levels (e.g., 0.1-0.4% lead) SO2 control (~98-99%) is typically through production of sulfuric acid (commercial product) due to high sulfur content of effluent gas (> 3%) PM controlled typically by electrostatic precipitators (95% control achievable) Title V Permit for Kennecott Utah Copper Particulate matter (PM): 50 mg/dscm Sulfur dioxide (SO2): 0.025% (6-hr) No visible emissions > 15% opacity

d=(1 – opacity)/s=-ln(1 – 0.2)/0.163 m-1 = 1.4 m Air Pollution Problem What is the optical path length at which the NSPS of 50 mg/dscm matches the visible emissions limit of 20% opacity? Lv = 1200/C = 1200/50,000 = 0.024 km = 24 m s=3.91/Lv = 3.91/24 m = 0.163 m-1 d=(1 – opacity)/s=-ln(1 – 0.2)/0.163 m-1 = 1.4 m