{"data":{"id":"us/40-cfr-421.263","jurisdiction":"us","citation":"40 CFR 421.263","heading":"Effluent limitations guidelines representing the degree of effluent reduction attainable by the application of the best available technology economically achievable.","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 available technology economically achievable:\n(a) Furnace wet air pollution control.\nBAT 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 5.760 2.745\nCyanide (total) 0.900 0.360\nZinc 4.590 1.890\nCombined metals 1.350\nAmmonia (as N) 599.900 263.700\n(b) Raw material granulation.\nBAT 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 in the granulated raw material\nCopper 0.819 0.390\nCyanide (total) 0.128 0.051\nZinc 0.653 0.269\nCombined metals 0.192\nPalladium 0.064\nPlatinum 0.064\nAmmonia (as N) 85.310 37.500\n(c) Spent plating solutions.\nBAT 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 1.280 0.610\nCyanide (total) 0.200 0.080\nZinc 1.020 0.420\nGold\nCombined metals 0.300\nAmmonia (as N) 133.300 58.600\n(d) Spent cyanide stripping solutions.\nBAT 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 4.736 2.257\nCyanide (total) 0.740 0.296\nZinc 3.774 1.554\nCombined metals 1.110\nAmmonia (as N) 493.200 216.800\n(e) Refinery wet air pollution control 2.\nBAT 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 1.280 0.610\nCyanide (total) 0.200 0.080\nZinc 1.020 0.420\nCombined metals 0.300\nAmmonia (as N) 133.300 58.600\n(f) Gold solvent extraction raffinate and wash water.\nBAT 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 0.806 0.384\nCyanide (total) 0.126 0.050\nZinc 0.643 0.265\nCombined metals 0.189\nAmmonia (as N) 83.980 36.920\n(g) Gold spent electrolyte.\nBAT 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 0.0111 0.0053\nCyanide (total) 0.0017 0.0007\nZinc 0.0089 0.0037\nCombined metals 0.0030\nAmmonia (as N) 1.1600 0.5100\n(h) Gold precipitation and filtration.\nBAT 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 5.632 2.684\nCyanide (total) 0.880 0.352\nZinc 4.488 1.848\nCombined metals 1.320\nAmmonia (as N) 586.500 257.800\n(i) Platinum precipitation and filtration.\nBAT 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 6.656 3.172\nCyanide (total) 1.040 0.416\nZinc 5.304 2.184\nCombined metals 0.560\nAmmonia (as N) 693.200 304.700\n(j) Palladium precipitation and filtration.\nBAT 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 7.680 3.660\nCyanide (total) 1.200 .480\nZinc 6.120 2.520\nCombined metals 1.800\nAmmonia (as N) 799.800 351.600\n(k) Other platinum group metals precipitation and filtration.\nBAT 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 6.656 3.172\nCyanide (total) 1.040 0.416\nZinc 5.304 2.184\nCombined metals 1.560\nAmmonia (as N) 693.200 304.700\n(l) Spent solutions from PGC salt production.\nBAT 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 1.152 0.549\nCyanide (total) 0.180 0.072\nZinc 0.918 0.378\nCombined metals 0.270\nAmmonia (as N) 120.000 52.740\n(m) Equipment and floor wash.\nBAT 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\nCombined metals 0.000\nAmmonia (as N) 0.000 0.000\n(n) Preliminary treatment.\nBAT 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 64.000 30.500\nCyanide (Total) 10.000 4.000\nZinc 51.000 21.000\nCombined metals 15.000\nAmmonia (as N) 6665.000 2930.000","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":"781a2c2b5bb228f8a9afc2430db381580467fbb73ffb9b37b3066be8c0d8b29d","source_id":"us-cfr","stale":true,"prev":"us/40-cfr-421.262","next":"us/40-cfr-421.264"},"notice":"GroundRules: Original legal text. Not legal advice."}