Iron and Steel Manufacturing 40 CFR Part 420 Description of the - - PowerPoint PPT Presentation

Iron and Steel Manufacturing

40 CFR Part 420

Three basic types for facilities

Integrated steel mills Non-integrated steel mills Stand-alone facilities

Description of the Industry

Iron and Steelmaking Operations

Forming & Finishing Operations

Two types of cokemaking facilities

By-product recovery coke plants

Waste ammonia liquor (ammonia, cyanide, sulfide, benzene, and phenols)

Non-recovery coke plants

Manufacturing Operations – Cokemaking (Subpart A)

By-Product Recovery Cokemaking

Recovered of iron-bearing materials are mixed with iron

• re, limestone,

and finely divided fuel.

Manufacturing Operations – Sintering (Subpart B)

Iron ore is reduced to molten iron in a blast furnace.

Manufacturing Operations – Ironmaking (Subpart C)

Q-BOP

Manufacturing Operations – Steelmaking (Subpart D)

Electric Arc Furnace

Low-tonnage carbon, alloy, and stainless steels

BOP

Basic Oxygen Furnace

High-tonnage carbon steels

Refining process in which gases are removed from molten steel prior to casting.

Manufacturing Operations – Vacuum Degassing (Subpart E)

Converts molten steel into a semi- finished product

• r shape through

water cooled molds.

Manufacturing Operations – Continuous Casting (Subpart F)

Preheated solidified steel is reshaped through a series of forming steps using mechanical pressure applied to work rolls.

Manufacturing Operations – Hot Forming (Subpart G)

Surface treatment operation. Two step operation

Molten salt baths Water quenching

Can be a batch or continuous process

Manufacturing Operations – Salt Bath Descaling (Subpart H)

Salt Bath Descaling – Batch Process

Salt Bath Descaling – Continuous Process

Chemically removes oxides and scale Carbon steel – hydrochloric acid Stainless steel – sulfuric, hydrochloric, and/or hydrofluoric acids

Manufacturing Operations – Acid Pickling

Process in which unheated steel is passed through rolls Reduces thickness Produces a smooth surface Develops controlled mechanical properties in the steel

Manufacturing Operations – Cold Forming (Subpart J)

Steel and steel products are immersed in alkaline cleaning baths and its rinsing operations There are no promulgated categorical standards for this subpart Facilities subject to this subpart must comply with the general pretreatment regulations at 40 CFR Part 403

Manufacturing Operations – Alkaline Cleaning

Involves immersing precleaned steel into molten metal baths of

Tin, Zinc (hot galvanizing), Combinations of lead and tin (terne coating), or Combinations of aluminum and zinc (galvalume coating)

Manufacturing Operations – Hot Coating (Subpart L)

Briquetting

Recycles and reuses fine materials Requires no discharge of process wastewaters to the POTW

Direct-Reduced Iron (DRI)

Similar iron making reaction as blast furnace ironmaking No pretreatment standards for this operation

Forging

Type of steel forming No pretreatment standards for this operation

Manufacturing Operations – Other (Subpart M)

Pretreatment standards are mass limits (production-based) pH limits of 6.0 to 9.0 [40 CFR 420.07] Part 420 regulates discharges of process wastewater generated in all production operations Co-treating non-process wastewater is allowed in some circumstances [40 CFR 420.02(r)] Additional pollutant allowances for non-process wastewater [40 CFR 420.08]

Implementation of Regulations

40 CFR Part 420 Process and Non-Process Wastewaters

Process and Non-Process Wastewaters (continued)

Subpart A: Cokemaking Additional loading allowance for wastewaters from specific processes (see 420.15 and 420.16). No discharge of process wastewater pollutant to POTWS from non-recovery cokemaking processes. Subpart B: Sintering No discharge of process wastewater pollutants to the POTWs from dry air pollution control systems. The pretreatment standards for cyanide and phenols apply only when sintering wastewater is co- treated with ironmaking wastewater. Special compliance monitoring point for 2,3,7,8- TCDF. Ammonia limit is not applicable if POTW has nitrification capabilities.

Other Special Conditions

Subpart C: Ironmaking The iron blast furnace ammonia limit is not applicable if POTW has nitrification capabilities. Subpart D: Steelmaking No discharge of process wastewater pollutants from the electric arc furnace steelmaking-semi-wet process and the basic oxygen furnace steelmaking- semi-wet process. Subpart J: Cold Forming Limitations for chromium and nickel are applicable

• nly if cold forming wastewaters are treated with

descaling or combination acid pickling wastewaters. Subpart L: Hot Coating) Limitations for hexavalent chromium is applicable

• nly to galvanizing operations which discharge

wastewaters from the chromate rinse step. Subpart M: Other Operations No discharge of process wastewater pollutants to POTWs from the briquetting operation.

Other Special Conditions

Calculating Limits - Example

2 tons of steel plate products Combination Acid Pickling Cold Forming Annealing Alkaline Cleaning Metal Finishing

Finished Product Combination acid pickling spend acid, rinse waters, and fume scrubber to treatment Spent rolling emulsions and solutions to treatment Alkaline rinse wastewater to treatment Plating rinse wastewater to treatment

Wastewater flows:

Alkaline cleaning prior to metal finishing: 50,000 gpd Metal finishing rinse wastewater: 35,000 gpd Total Wastewater Flow per day: 200,000 gpd

The alkaline cleaning prior to the metal finishing and the metal plating rinse wastewaters are subject to 40 CFR Part 433 (PSNS) The reminder of the wastewaters are subject to 40 CFR Part 420 (PSNS)

Calculating Limits (continued)

Operation Production Pollutant – Chromium Units Daily Max 30 day average Combo Acid Pickling [420.96(c)(3)] 2 tons per day 0.000710 0.000284 lbs/1,000 lbs 0.00284 0.001136 lbs/day Combo Acid Pickling (fume scrubber) [420.96)(c)(6) Facility does have one fume scrubber over the pickling bath 0.0819 0.0327 kg/day 0.181 0.0721 lbs/day Cold-Forming [420.106(a)(2)] 2 tons per day 0.0000418 0.0000167 lbs/1,000 lbs 0.0001672 0.0000668 lbs/day Metal Finishing [433.17] Not applicable 2.77 1.71 mg/L 1.96 1.21 lbs/day Total Allowable Mass (Chromium) 2.14 1.28 lbs/day Adjust concentration limits 1.28 0.77 mg/L

Calculating Limits (continued)

Physical / Chemical Treatment

Equalization Tar Removal Ammonia Stripping Cyanide and Metals Removal Oily Waste Treatment Solids Separation Carbon Dioxide Injection Polishing

Treatment Options

Ammonia Stripping

Biological Treatment

Conventional Activated Sludge Sequencing Batch Reactor Attached Growth/Fixed Film Biological Denitrification

Sludge Handling

Gravity Thickening Rotary Vacuum Filtration Pressure Filtration Belt Filtration Centrifugation Sludge drying

Treatment Options

Routine Monitoring Flow Management Training and Supervision Production Planning and Sequencing Process or Equipment Modification Raw Material and Product Substitution or Elimination Oil Management and Preventive Maintenance Loss Prevention and Housekeeping Waste Segregation and Separation

Best Management Practices