{"data":{"id":"us/40-cfr-421.262","jurisdiction":"us","citation":"40 CFR 421.262","heading":"Effluent limitations guidelines representing the degree of effluent reduction attainable by the application of the best practicable control technology currently available.","body":"Except as provided in 40 CFR 125.30 through 125.32, any existing point source subject to this subpart shall achieve the following effluent limitations representing the degree of effluent reduction attainable by the application of the best practicable technology currently available:\n(a) Furnace wet air pollution control.\nBPT Limitations for the Secondary Precious Metals Subcategory\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/troy ounce of precious metals, including silver, incinerated or smelted\nCopper 136.400 71.800\nCyanide (total) 20.820 8.616\nZinc 104.800 43.800\nAmmonia (as N) 9,571.000 4,207.000\nCombined metals 21.54\nTotal suspended solids 2,944.000 1,400.000\npH (1) (1)\n1 Within the range of 7.5 to 10.0 at all times.\n(b) Raw material granulation.\nBPT Limitations for the Secondary Precious Metals Subcategory\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/troy ounce of precious metal in the granulated raw material\nCopper 12.050 6.340\nCyanide (total) 1.839 0.761\nZinc 9.256 3.867\nAmmonia (as N) 845.100 371.500\nCombined metals 1.902\nTotal suspended solids 259.900 123.600\npH (1) (1)\n1 Within the range of 7.5 to 10.0 at all times.\n(c) Spent plating solutions.\nBPT Limitations for the Secondary Precious Metals Subcategory\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/liter of spent plating solution used as a raw material\nCopper 1.900 1.000\nCyanide (total) 0.290 0.120\nZinc 1.460 0.610\nAmmonia (as N) 133.300 58.600\nCombined metals 0.300\nTotal suspended solids 41.000 19.500\npH (1) (1)\n1 Within the range of 7.5 to 10.0 at all times.\n(d) Spent cyanide stripping solutions.\nBPT Limitations for the Secondary Precious Metals Subcategory\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/troy ounce of gold produced by cyanide stripping\nCopper 7.030 3.700\nCyanide (total) 1.073 0.444\nZinc 5.402 2.257\nAmmonia (as N) 493.200 216.800\nCombined metals 1.110\nTotal suspended solids 151.700 72.150\npH (1) (1)\n1 Within the range of 7.5 to 10.0 at all times.\n(e) Refinery wet air pollution control. 2\nBPT Limitations for the Secondary Precious Metals Subcategory\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/troy ounce of precious metals, including silver, produced in refinery\nCopper 39.900 21.000\nCyanide (total) 6.090 2.520\nZinc 30.660 12.810\nAmmonia (as N) 2,799.000 1,231.000\nCombined metals 6.300\nTotal suspended solids 861.000 409.500\npH (1) (1)\n1 Within the range of 7.5 to 10.0 at alltimes.\n(f) Gold solvent extraction raffinate and wash water.\nBPT Limitations for the Secondary Precious Metals Subcategory\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/troy ounce of gold produced by solvent extraction\nCopper 1.197 0.630\nCyanide (total) 0.183 0.076\nZinc 0.920 0.384\nAmmonia (as N) 83.980 36.920\nCombined metals 0.189\nTotal suspended solids 25.830 12.290\npH (1) (1)\n1 Within the range of 7.5 to 10.0 at all times.\n(g) Gold spent electrolyte.\nBPT Limitations for the Secondary Precious Metals Subcategory\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/troy ounce of gold produced by electrolysis\nCopper 0.017 0.009\nCyanide (total) 0.003 0.001\nZinc 0.103 0.005\nAmmonia (as N) 1.160 0.510\nCombined metals 0.003\nTotal suspended solids 0.357 0.170\npH (1) (1)\n1 Within the range of 7.5 to 10.0 at all times.\n(h) Gold precipitation and filtration.\nBPT Limitations for the Secondary Precious Metals Subcategory\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/troy ounce of gold precipitated\nCopper 8.360 4.400\nCyanide (total) 1.276 0.528\nZinc 6.424 2.684\nAmmonia (as N) 586.500 257.800\nCombined metals 1.320\nTotal suspended solids 180.400 85.800\npH (1) (1)\n1 Within the range of 7.5 to 10.0 at all times.\n(i) Platinum precipitation and filtration.\nBPT Limitations for the Secondary Precious Metals Subcategory\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/troy ounce of platinum precipitated\nCopper 9.880 5.200\nCyanide (total) 1.508 0.624\nZinc 7.592 3.172\nAmmonia (as N) 693.200 304.700\nCombined metals 1.560\nTotal suspended solids 213.200 101.400\npH (1) (1)\n1 Within the range of 7.5 to 10.0 at all times.\n(j) Palladium precipitation and filtration.\nBPT Limitations for the Secondary Precious Metals Subcategory\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/troy ounce of palladium precipitated\nCopper 11.400 6.000\nCyanide (total) 1.740 0.720\nZinc 8.760 3.660\nAmmonia (as N) 799.800 351.600\nCombined metals 1.800\nTotal suspended solids 246.000 117.000\npH (1) (1)\n1 Within the range of 7.5 to 10.0 at all times.\n(k) Other platinum group metals precipitation and filtration.\nBPT Limitations for the Secondary Precious Metals Subcategory\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/troy ounce of other platinum group metals precipitated\nCopper 9.880 5.200\nCyanide (total) 1.508 0.624\nZinc 7.592 3.172\nAmmonia (as N) 693.200 304.700\nCombined metals 1.560\nTotal suspended solids 213.200 101.400\npH (1) (1)\n1 Within the range of 7.5 to 10.0 at all times.\n(l) Spent solution from PGC salt production.\nBPT Limitations for the Secondary Precious Metals Subcategory\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/troy ounce of gold contained in PGC product\nCopper 1.710 0.900\nCyanide (total) 0.261 0.108\nZinc 1.314 0.549\nAmmonia (as N) 120.000 52.740\nCombined metals 0.270\nTotal suspended solids 36.900 17.550\npH (1) (1)\n1 Within the range of 7.5 to 10.0 at all times.\n(m) Equipment and floor wash.\nBPT Limitations for the Secondary Precious Metals Subcategory\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/troy ounce of precious metals, including silver, produced in refinery\nCopper 0.000 0.000\nCyanide (total) 0.000 0.000\nZinc 0.000 0.000\nAmmonia (as N) 0.000 0.000\nCombined metals 0.000 0.000\nTotal suspended solids 0.000 0.000\npH (1) (1)\n1 Within the range of 7.5 to 10.0 at all times.\n(n) Preliminary treatment.\nBPT Limitations for the Secondary Precious Metals Subcategory\nPollutant or pollutant property Maximum for any 1 day Maximum for monthly average\nmg/troy ounce of total precious metals produced through this operation\nCopper 95.000 50.000\nCyanide (Total) 14.500 6.000\nZinc 73.000 30.500\nAmmonia (as N) 6665.000 2930.000\nCombined Metals 15.000\nTotal Suspended Solids 2050.000 975.000\npH (1) (1)\n1 Within the range of 7.5 to 10.0 at all times.","path":["Title 40—Protection of Environment","CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY","SUBCHAPTER N—EFFLUENT GUIDELINES AND STANDARDS","PART 421—NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY","Subpart X—Secondary Precious Metals Subcategory"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-40.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:26:04Z","sha256":"53b26421248eebdda4871f28d35fcfe9c01e38ed7819deb460be6267f982d619","source_id":"us-cfr","stale":true,"prev":"us/40-cfr-421.261","next":"us/40-cfr-421.263"},"notice":"GroundRules: Original legal text. Not legal advice."}