CHAPTER 35

PERSPECTIVES ON SPECIFIC SUBSTANCES: SULFURIC ACID Richard Lawuyi and Merv Fingas Emergencies Science Division, Environment Canada, Environmental Technology Centre, River Road, Ottawa, Ontario

35.1

OVERVIEW OF PRODUCT AND INDUSTRIAL USES Sulfuric acid is a corrosive, oily, and colorless liquid well known since the Middle Ages. It is a good dehydrating and drying agent and has been an important commercial commodity for more than three centuries. Until the late 1960s, sulfuric acid production and consumption were generally accepted throughout the industrialized world as an accurate barometer of a nation’s commercial activity and wealth. Nowadays, because of its extensive use in the agriculture industry, sulfuric acid no longer measures a country’s wealth. Nevertheless, more sulfuric acid is produced and spilled in the chemical industry today than any other chemical. It is indispensable in many chemical and industrial processes. The market for sulfuric acid is still very strong and will continue to grow. Canada has an abundant supply of sulfur deposits, and sulfur occurs naturally in natural gas and metal ores. Sulfuric acid can therefore be produced cheaply for both domestic use and export. Sulfuric acid is used primarily to produce phosphate fertilizers by the phosphoric acid route. It also has many uses in the processing industry, including kraft bleaching; in copper, petroleum, and uranium refineries; to manufacture various salts such as magnesium sulfate; to manufacture soaps and detergents; in electroplating and metallurgy; and to produce various chemical reagents such as phenols, alums, alkylation catalysts, explosives, propellants, fibers, electronic chips, pharmaceuticals, and acid batteries.

35.1.1

Modern Industrial Uses

The estimated consumption of sulfuric acid in 1996 by the industrial sector in the United States is shown in Figure 35.1. In Canada, while fertilizer consumption is not as prominent, consumption of sulfuric acid follows a similar pattern to that in the United States: fertilizers—68%; mining—5.8%; miscellaneous—10.6%; inorganics—5.1%; others, including petroleum refining and products, synthetic rubber and plastics, pulp mills and other paper products, and industrial organic chemicals—10.5% (CIS, 1997). Sulfuric acid consumption is very stable and should continue to be so. 35.1

35.2

CHAPTER THIRTY-FIVE

Fertilizers

Others Inorganics Mining

Miscellaneous

FIGURE 35.1 Uses of sulfuric acid in the United States in 1996.

35.2

INTRODUCTION Sulfuric acid was apparently discovered in the 8th century by a Persian alchemist who distilled niter (potassium nitrate) with green vitriol (ferrous sulfate crystals) obtained from weathered iron pyrites. Several alchemists, including Jabir ibn Hayyan, Vincentius de Beauvais (1240), Albertus Magnus (1193–1280), Paracelsus, Gerhard Dornaeus (1570), Andreas Libavius (1595), Angelus Sala (1613), Nicholas le Fevre (1666), Nicholas Lemery, and Cornelius Drebbel, tried to improve on his methodology. By the middle of the 12th century, Occidental alchemists were also producing sulfuric acid from sulfur and pyrites. Following Lavoisier’s discovery in the 18th century that sulfur is a chemical element and not a mixture, production of sulfuric acid from sulfur and pyrites was commercialized in many parts of the world (Duecker and West, 1959). In approximately 1740 in Great Britain, Ward began to produce the acid on a large-scale by burning sulfur with potassium nitrate. In 1746, Dr. Roebuck of Birmingham introduced the lead chamber process and built a factory in Scotland to manufacture the acid. This practice quickly spread throughout Europe and North America In North America, commercial production of sulfuric acid began in 1797 when John Harrison built a sulfuric acid plant in Philadelphia. Much research has since been done on the nature of the catalyst and feedstock. In the late 1800s, the lead chamber process was gradually replaced by the contact process, patented by Phillips in 1831. In 1875, Emil Jacob successfully demonstrated the new process and the modern contact acid manufacture of the acid began with a pyrite-burning gas as the source of sulfur dioxide. Today, a large proportion of the sulfuric acid produced in the world is what is termed ‘‘fatal’’ acid, which is manufactured to prevent substantial amounts of waste sulfur dioxide formed in metallurgical and smelting processes, such as nonferrous metal smelting and iron production from pyrites, from entering the environment (Inco Limited, 1985; Muller, 1997).

PERSPECTIVES ON SPECIFIC SUBSTANCES: SULFURIC ACID

35.3

Many of the environmental and technical problems associated with the large-scale production, handling, and shipment of sulfuric acid are now fairly well understood. Today, emissions, effluent discharge, handling, and shipping are governed by national and international regulations and codes.

35.2.1

Spill Profile

For the last few years, sulfuric acid has been one of the most commonly spilled substances (Environment Canada, 2000). The annual frequency of spills of sulfuric acid from 1990 to 1996 is shown in Figure 35.2. It can be seen that the number of spills is slowly decreasing. Chemical burns are the most prevalent hazard from spills of sulfuric acid. Its main properties, including physical, chemical, toxicological, behavioral, and environmental fate, are outlined in Section 35.3.

35.2.2

Priority List Ranking

According to a study to determine the minimum number of hazardous chemicals most frequently spilled, sulfuric acid is sixth on the list, with the highest supply volume (Fingas et al., 1991). It also has one of the highest numbers of spills. The priority list was developed by a simple ranking of: (1) reported spill frequency; (2) supply volumes; (3) historical spill volumes; and (4) toxicities. Table 35.1 shows how sulfuric acid ranks in Environment Canada’s priority listing of hazardous chemicals.

35.3

PHYSICAL AND CHEMICAL PROPERTIES AND GUIDELINES SUMMARY

Sulfuric acid: Sulfuric acid is a colorless (when pure) to dark brown, oily liquid with a sharp, penetrating odor. Molecular formula: H2SO4 Molecular weight: 98.08 CAS number: 7664-93-9 UN number: 1830 Fuming: 1831 Spent: 1832 STCC number: 4930040 Spent: 4930042 OHM-TADS number: 7216915 Labels: Corrosive Corrosive and poison (fuming)–IMO Synonyms and trade names (RTECS On-Line, 1999):

35.4

CHAPTER THIRTY-FIVE

FIGURE 35.2 Spill profile of sulfuric acid (1990–1996).

Sulfuric Acid Acide sulfurique Battery acid Electrolyte acid Fertilizer acid Hydrogen sulfate Oil of vitriol Spirit of sulfur Sulphuric acid Acido solforico Bov TABLE 35.1 Priority List Ranking of Sulfuric Acid

Chemical

Ranking

Spill numbers

Spill volume (thousand tons)

Supply volume (million tons)

Ammonia Chlorine Tetraethyllead Styrene PCBs Sulfuric acid Sodium cyanide Hydrochloric acid Potassium chloride Pentachlorophenol Phenol Zinc sulfate Phosphorus Toluene

1 2 3 4 5 6 7 8 9 10 11 12 13 14

107 36 4 24 334 155 3 123 31 19 10 3 16 13

470 120 72 5,000 89 13,000 83 3,300 12,000 110 14 68 46 110

3,700 1,700 26 630 – 3,700 12 170 – 1.5 68 1,500 68 430

PERSPECTIVES ON SPECIFIC SUBSTANCES: SULFURIC ACID

35.5

Dipping acid Matting acid Nordhaausen acid Spent sulfuric acid Schwefelsa¨urelo¨esungen Vitriol brown oil Zwavelzuuroplossingen Fuming sulfuric acid (sulfuric acid with dissolved SO3): Disulfuric acid Dithionic acid Fuming sulfuric acid Fuming sulfuric acid Oleum Pyrosulfuric acid Grades and Purities (Kirk-Othmer, 1983; Budavari, 1989): Pure sulfuric acid is a colorless, oily liquid. When impure, it is brownish. The pure acid decomposes into sulfur trioxide and water at 340⬚C. It is soluble in water and alcohol with evolution of heat. Spent sulfuric acid is a black oily liquid. It is also soluble in water with release of heat. Impurities are iron, arsenic, sulfur dioxide, nitrogen compounds, chloride, and fluoride. Grade

Minimum purity mole %1 (liquid phase)

Commercial (technical) Electrolyte-battery acid Chemically pure (CP) USP Sulfuric acid (fuming)

75; 78; 88; 93; 96; 98 to 99; and 100 ⬎93.19 95.5 to 96.5 – Sulfuric acid and SO3 20% oleum (104.5%); 40% oleum (109.0%); 65% oleum (114.63%)

1

Impurity is mostly water and some metals.

Strengths: Sulfuric acid: Degrees Baume´

% H2SO4

Specific gravity at 17.78⬚C

52 58 60 66 – –

65.13 74.36 77.67 93.19 98.00 100.00

1.5591 1.6667 1.7059 1.8354 1.8438 1.8392

Freezing point (⬚C) ⫺40.0 ⫺44.0 ⫺8.0 ⫺32.0

3.0 10.0

Fuming sulfuric acid: Oleum, % free SO3

% Equivalent H2SO4

Specific gravity (37.78)

20.0 30.0 40.0 65.0 100.0

104.50 106.75 109.00 114.63 122.50

1.8820 1.9156 1.9473 1.9820 1.8342

Freezing point (⬚C) ⫺9.0

15.5 33.0 3.6 16.8

35.6

CHAPTER THIRTY-FIVE

Physical data: Concentrated sulfuric acid: Physical state: Liquid (Budavari, 1989) Boiling point: 330 Ⳳ 0.5⬚C (100%) Melting point: 10.36⬚C (100%) Solubility (water): Infinity (heat evolved) Density, liquid: 1.841 (96 to 98%) Vapor pressure (mm Hg): 1 at 146⬚C Specific gravity (water ⫽ 1): 1.841 Flammability: Not flammable Vapor density (air ⫽ 1): 3.4 Behavior (in water): Sinks, reacts with heat evolution Odor threshold and range: Low concentration is odorless; in fire, high concentration emits SO3 with an odor threshold ⬎1 mg / m3 Sulfuric acid solution in water 93 to 98% State (15⬚C, 1 atm): Liquid Melting point: ⫺32⬚C (93%) Relative density: 1.8 (water ⫽ 1) Solubility in water: Infinity Sulfuric acid is a dense, colorless liquid at room temperature. In the past, its concentration was described as a function of its specific gravity in degrees Baume´ (⬚Be´). In the United States, the Baume´ scale is calculated using the following formula: ⬚B´e ⫽ 145 ⫺ (145 / specific gravity)

In Germany and France, the Baume´ scale is calculated using 144.3 as the constant. The Baume´ scale includes only concentrations in the range of 0 to 93.19% H2SO4. The scale does not extend to higher concentrations ranging from 93 to 100% H2SO4. Sulfuric acid: Appearance: Clear to cloudy fuming liquid Usual shipping state: Liquid Physical state at room temperature and pressure: Liquid Melting point: % H2SO4 65 65.13 74.36 75 77.67 78 88 93 93.19 96 98.00 100.00

⬚C ⫺64 ⫺40.0 ⫺44.0 ⫺12 ⫺8.0 ⫺38 ⫺20 ⫺35 ⫺32.0 ⫺14

3.0 10.0

Be´ 52⬚ 58⬚ 60⬚

66⬚

PERSPECTIVES ON SPECIFIC SUBSTANCES: SULFURIC ACID

% oleum 20.0 30.0 40.0 65.0 100.0 Boiling point: % H2SO4 98 96 93 75 % oleum 20

35.7

⬚C ⫺9.0

15.5 33.0 3.6 17.2 ⬚C

340

⬃310

279

⬃193 ⬚C

142

Decomposition temperature: 340⬚C (Budavari, 1989) Vapor pressure (mm Hg): mm Hg % H2SO4 96 1 at 146⬚C 93 1 at 145.8⬚C Densities: Specific gravity: Density %H2SO4 96 1.84 93 1.835 88 1.50 ⬃1.674 at 15.5⬚C 75 ⫹20% SO3 1.92 Vapor density (air ⫽ 1): V.D. % H2SO4 96 ⬍0.3 at 25⬚C 93 3.4 Fire properties: Flammability: Nonflammable. Highly reactive and capable of igniting finely divided, combustible materials on contact. Behavior in fire: Emits toxic fumes. Decomposition temperature: 340⬚C (Budavari, 1989). Decomposition products: Toxic fumes of sulfur oxides. Other properties: Molecular weight: 98.08 (Budavari, 1989) Grades (minimum purity %): Commercial (technical) 75% 78% 93% 96% 98 to 99% 100%

35.8

CHAPTER THIRTY-FIVE

⬎93.19 95.5 to 96.5 – 80% H2SO4 ⫹ 20% SO3 60% H2SO4 ⫹ 40% SO3 35% H2SO4 ⫹ 65% SO3 Refractive index: 1.4297 (for 100% H2SO4) Viscosity: Viscosity (cp) Temp. ⬚C (for 100% H2SO4) 48.4 0 32.8 15 25.4 20 15.7 30 11.5 40 8.82 50 7.22 60 6.09 70 5.19 80 Surface tension, 25⬚C (compared to water): mN / m % wt H2SO4 4.11 72.21 8.26 72.55 12.18 72.80 17.66 73.36 21.88 73.91 29.07 74.80 33.63 75.29 Surface tension, 20⬚C (with vapor or air): mN / m % wt H2SO4 98.5 55.1 Hygroscopicity: Hygroscopic Latent heat of fusion: 2360 cal / g mole (9.8 kJ / mole at melting point) Latent heat of vaporization: 56 kJ / mole (at boiling point) Heat of formation: ⫺813.9 kJ / mole (25⬚C) Heat of solution: ⫺971.5 kJ / kg Heat capacity (Cp) constant pressure: 138.9 J / mole⬚C (25⬚C) Coefficient of thermal expansion (20⬚C): 0.5758 ⫻ 10⫺3 (100% solution); 0.2835 ⫻ 10⫺3 (10.9% solution) 0.21 Thermal conductivity (30⬚C): 90% 60% 0.25 30% 0.30 Diffusivity: 1.97 ⫻ 10⫺5 cm2 / s (water, 25⬚C) pH of aqueous solution: 0.3, 1 N solution at 25⬚C Eutectic compositions: 36% aqueous solution (freezing point, ⫺64⬚C) Solubility: Water: Soluble in water. Reacts violently with evolution of heat. Spattering occurs when water is added to sulfuric acid.

Electrolyte battery acid Chemically pure (CP) USP Fuming sulfuric acid (oleum)

PERSPECTIVES ON SPECIFIC SUBSTANCES: SULFURIC ACID

35.9

Properties of sulfur trioxide (Kirk-Othmer, 1983): Critical temperature: 217.8⬚C Critical pressure: 8,208 kPa Critical density: 0.630 g / cm3 Triple point temperature (␥ phase): 16.8⬚C Triple point pressure (␥ phase): 21.13 kPa Normal boiling point: 44.8⬚C Melting point (␥ phase): 16.8⬚C Transition temperature: ⫺183.0⬚C Liquid density (␥ phase at 20⬚C): 1.9224 g / cm3 Solid density (␥ phase at ⫺10⬚C): 2.29 g / cm3 Liquid coefficient of thermal expansion, 18⬚C: 0.002005 per ⬚C Liquid heat capacity at 30⬚C: 3.222 kJ / (kg⬚C) Heat of formation of gas at 25⬚C: ⫺395.76 (MJ 䡠 kg) / mol Free energy of formation of gas at 25⬚C: ⫺371.07 (MJ 䡠 kg) / mol Entropy of gas at 25⬚C: 0.25666 (MJ 䡠 kg) / (mol 䡠 ⬚C) Heat of dilution: 2.109 MJ / kg Heat of fusion, ␣: 324.0 kJ / kg ␤: 151.6 kJ / kg ␥: 94.07 kJ / kg Heat of sublimation, ␣: 0.8518 MJ / kg ␤: 0.7269 MJ / kg ␥: 0.7029 MJ / kg Heat of vaporization (␥ liquid): 0.5843 MJ / kg Diffusion in air at 80⬚C: 0.000013 m / s Liquid dielectric constant at 18⬚C: 3.11 Electric conductivity: Negligible

35.3.1

Summary of Chemical Properties and Behavior (Bailar et al., 1975)

Sulfuric acid is a strong mineral acid, one of the most important compounds of sulfur and one of the best known nonaqueous protonic solvents. The sulfur atoms are surrounded symmetrically by four oxygen atoms and are therefore highly associated because of the strong intermolecular hydrogen bonding. At the boiling point, sulfuric acid solutions containing less than 85% H2SO4 evaporate water exclusively, while those containing more than 35% free SO3 (oleum) evaporate sulfur trioxide exclusively. The vapor of sulfuric acid solutions in between these two concentrations (85% H2SO4 to ⬎35% oleum) is a mixture of sulfuric acid, water, and sulfur trioxide. Sulfuric acid is miscible with water in all concentrations. The heat of hydration is very high, about 210 kcal / mole at infinite dilution. Sulfuric acid forms hydrates, such as H2SO4 䡠 H2O, H2SO4 䡠 2H2O, and H2SO4 䡠 3H2O, in the presence of water.

35.3.2

Physiological Effects of Sulfuric Acid

The physiological effects of exposure to sulfuric acid fumes depend on the particle size of the aerosol. Thus, for a constant sulfuric acid aerosol concentration, the irritant action of the aerosol increases with aerosol particle size. Other factors are humidity, temperature, and previous exposure. Several studies have shown that prolonged exposure to sulfuric acid causes tooth erosion, while overexposure to sulfuric acid aerosols leads to pulmonary edema, chronic pulmonary fibrosis, residual bronchiectasis, and pulmonary emphysema. The thresh-

35.10

CHAPTER THIRTY-FIVE

old limit value (TLV) for sulfuric acid mist for humans is 1 mg / m3. This threshold is recommended to prevent injury to the teeth and pulmonary irritation at particle sizes likely to occur in industrial settings. Eye contact may result in loss of vision, while skin contact may produce severe necrosis. If ingested, gastric perforation and peritonitis may occur, possibly followed by circulatory collapse. A few drops may be fatal if the acid gains access to the trachea.

35.3.3

Main Hazards

General: Sulfuric acid is a very corrosive, colorless liquid that may exhibit violent chemical changes at elevated temperatures and pressures and may react violently with water. Inhalation of vapor may cause serious lung damage, and contact with eyes may result in total loss of vision. Skin contact may cause burning and severe necrosis. Sulfuric acid is highly reactive and capable of igniting finely divided combustible materials on contact. It will char wood and many other organic materials on contact and emits toxic fumes when heated. Human health: Sulfuric acid is corrosive to all body tissues. Inhalation can paralyze the respiratory system, contact with eyes may result in loss of vision, and skin contact may result in severe burns and necrosis. Swallowing may cause severe injury or death. Between one teaspoonful and half an ounce of the concentrated acid may be fatal if swallowed, and an even smaller quantity may be fatal if inhaled. Chronic exposure may cause tracheobronchitis, stomatitis, conjunctivitis, and gastritis. Gastric perforation and peritonitis may occur and may be followed by collapse of the circulatory system. Pulmonary fibrosis, bronchiectasis, and emphysema have been reported from acute exposure to fuming sulfuric acid and sulfuric acid mist. Chronic exposure usually results in erosion of the teeth, particularly the incisors. Environment: Sulfuric acid is a powerful acidic oxidizer and a strong dehydrating agent. It is harmful to many microorganisms, plants, and aquatic life in concentrations as low as 6 mg / L. Behavior in Air: Sulfuric acid is not combustible, but many reactions may cause fire and explosion and produce fumes in the air. Behavior in Water: Concentrated sulfuric acid reacts violently with water and produces heat.

35.3.4

Emergency Response–Human Health

Symptoms: Local: Conjunctivitis, corneal necrosis, dermatitis, skin burns, ulceration, fainting. May lead to pulmonary edema, nausea, and vomiting. Respiratory: Irritation of the nose and throat, coughing, sneezing, laryngeal edema, bronchitis, pneumonitis, and pulmonary edema. Gastrointestinal: Dental erosion, shock, anuria; burning in the mouth, throat, and abdomen; nausea, vomiting of blood and eroded tissue; perforation of gastrointestinal tract; and albumin, blood, and casts in urine. Treatment: Inhalation: Move victim to fresh air. If not breathing, give artificial respiration.

PERSPECTIVES ON SPECIFIC SUBSTANCES: SULFURIC ACID

35.11

If breathing is difficult, give oxygen. During transportation: Continue giving oxygen by 40% venturi mask. Observe vital signs. In emergency room: Check arterial blood gas. Perform a chest X ray. Observe for pulmonary edema and bronchospasms. Skin: Wash and flush with water immediately. Remove clothing. Shower thoroughly. During transportation: Cover affected areas with sterile wet dressings immediately. In emergency room: Treat as burn. Eyes: Rinse well with large quantities of water for 15 minutes. Hold eyelids open while washing. During transportation: Continue eye rinsing. In emergency room: Continue eye rinsing (use Mediflow lens if available). Determine nature and extent of corneal damage. Notify an ophthalmologist. Ingestion: Do not induce vomiting. During transportation: Keep victim comfortable in an upright position. Support circulation. In emergency room: Do not lavage. Treat as acid ingestion.

35.3.5

Spill Control

Wear self-contained breathing apparatus and full protective clothing for all emergency measures involving sulfuric acid. Leaks: Keep the acid away from water sources and sewers. Build dikes to contain flow as necessary. Neutralize spilled material with agricultural lime (CaO), crushed limestone (CaCO3), soda ash, or sodium bicarbonate. Keep material out of water sources and showers and spray large liquid spills with vapor-smothering foams. Fires: Sulfuric acid does not burn by itself. Use a dry chemical to smother small fires involving combustibles. Use water in flooding quantities as fog to cope with large fires. Cool affected containers with flooding quantities of water. Apply water from as far away as possible. Spills: Wear appropriate chemical protective gloves, boots, and goggles. Avoid contact with contaminated material. Evacuate spill site and restrict access. Issue warning: ‘‘Corrosive, Poison.’’ Notify manufacturer and relevant authorities. Contain spill if it is safe to do so. Avoid contact with liquid or vapor. Stay upwind. Vapor cloud collects in low-lying

35.12

CHAPTER THIRTY-FIVE

areas. Keep contaminated water from entering sewers or watercourses. For small liquid spills, neutralize with lime. For large liquid spills, contain spill as much as possible. Neutralize spilled material with crushed limestone, soda ash, or lime. Land spill: Dig a pit, pond, lagoon, or holding area to contain the acid. Dike surface flow using soil, sand bags, foamed polyurethane, or foamed concrete. Absorb bulk liquid with fly ash or cement powder. Neutralize with agricultural lime (CaO), crushed limestone (CaCO3), or sodium bicarbonate (NaHCO3). Air spill: Apply water spray or mist to knock down vapors. Liquid produced is corrosive and toxic; it should be diked and neutralized. Water spill: Neutralize with agricultural lime (CaO), crushed limestone (CaCO3), or sodium bicarbonate (NaHCO3).

Immediate Concerns Hazard: Extremely corrosive. Rapidly destroys human tissues on contact. Causes severe burns. Sharp, penetrating odor. May react with other chemicals, causing fires and explosions. Fumes are very toxic. Powerful oxidizer. May react violently with water. May exhibit violent chemical changes at elevated temperatures and pressures. Humans: Corrosive to skin, eyes, and respiratory system. Will cause burns. Toxic by all routes, causing severe damage to tissues. Death may result. Environment: Harmful to aquatic life and the environment. Protection: Complete self-contained breathing apparatus recommended with face mask, suit, boots, and gloves (rubber, neoprene, or plasticized PVC).

35.3.6

Guidelines

The following are some emergency response guidelines provided by the American Industrial Hygiene Association (AIHA) for use during large releases of sulfuric acid (AIHA, 1988). ERPG-3: 30 mg / m3 (as sulfuric acid mist): The maximum airborne concentration below which it is believed that nearly all individuals could be exposed for up to one hour without experiencing or developing life-threatening health effects. ERPG-2: 10 mg / m3 (as sulfuric acid mist): The maximum airborne concentration below which it is believed that nearly all individuals could be exposed for up to one hour without experiencing or developing irreversible or other serious health effects or symptoms that could impair an individual’s ability to take protective action. ERPG-1: 2 mg / m3 (as sulfuric acid mist): The maximum airborne concentration below which it is believed that nearly all individuals could be exposed for up to one hour without experiencing other than mild, transient adverse health effects or without perceiving a clearly defined objectionable odor. Threshold Limit Values The American Conference of Governmental Industrial Hygienists (ACGIH) has determined the threshold limit values for TWA(time-weighted average) to be 1 mg / m3 and STEL (short-term exposure limit) to be 3 mg / m3. The ACGIH also recommends a TLV of 1 mg / m3 for sulfuric acid to prevent pulmonary irritation and injury to the teeth.

PERSPECTIVES ON SPECIFIC SUBSTANCES: SULFURIC ACID

35.13

The Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) is 1 mg / m3. The National Institute for Occupational Safety and Health (NIOSH) recommended exposure limit (REL) is 1 mg / m3 (10-hr TWA).

35.4

35.4.1

INDUSTRIAL ASPECTS AND PRODUCTION IN THE UNITED STATES, CANADA, AND WORLDWIDE Manufacture of Sulfuric Acid

Until the late 1800s, sulfuric acid was produced mainly by the lead chamber process, which uses nitrogen oxides as homogenous catalysts for the sulfur dioxide oxidation step. The feedstocks were sulfur, iron pyrites, nonferrous pyrites, hydrogen sulfide, and spent sulfuric acid. Nowadays, approximately 99% of all production is by the contact process. Sulfuric acid is also manufactured to prevent the substantial quantities of waste sulfur dioxide produced in metallurgical processes, such as the smelting of non-ferrous metals like nickel and copper and iron production from pyrites, from entering the environment. Sulfur dioxide produced during roasting of sulfide ores is sometimes referred to as roaster gas. Hydrogen sulfide gas is another useful raw material for the manufacture of sulfuric acid. The following are the steps involved in the production of SO2 for the contact process. 1. As the sulfide ores (pyrites) are roasted, the roaster gas and the metal oxides produced are separated from each other in cyclones. 3 Fe7S8 ⫹ 38 O2 2 Fe3O4 ⫹ 24 SO2

(35.1)

Ni3S2 ⫹ 2 O2 → 3 Ni ⫹ 2 SO2

(35.2)

2. The roaster gas is mixed with additional air to complete the combustion of all volatilized products. 3. Any remaining metal oxides in the roaster gas are removed by cooling and contacting with sulfuric acid solution. 4. The roaster gas is then passed through a further stage of washing and drying, followed by a wet precipitation stage. 5. Following the primary converter, the process gas passes through an interpass absorption tower. This tower removes SO3 from the process gas to provide improved equilibrium conditions for further oxidation of SO2 to SO3 in a second converter. SO3 produced in the second converter is absorbed in the final absorber. 6. The roaster gas is catalytically oxidized to sulfur trioxide in a fixed bed converter which operates adiabatically with each catalyst pass. 2SO2 ⫹ O2
 2SO3

(35.3)

7. The gas is now cooled and allowed to flow into the packed towers, where it is absorbed. The production of fuming sulfuric acid (oleum), however, requires sulfur trioxide absorption in special absorption towers irrigated with oleum. The reaction is exothermic. SO3 ⫹ H2O → H2SO4

(35.4)

35.14

CHAPTER THIRTY-FIVE

35.4.2

Manufacturers in Canada and the United States

Canadian and American manufacturers of sulfuric acid are listed here. It should be added that some of these plants have been mothballed and others may have changed hands or closed. Canadian manufacturers Sherritt Alcan Smelters and Chemicals Allied Chemical Canada Border Chemical Brunswick Mining and Smelting Cameco Canadian Electrolytic Zinc Cogema Resources Cominco Falconbridge Gaspe´ Copper Mines Hudson Bay Mining ICI Canada Inco International Minerals and Chemicals Kidd Creek Mines Kronos Canada Lever Marsulex Noranda Solv-Ex Sulco Chemicals Sulconam Westcoast Energy Western Co-operative Fertilizers American manufacturers Akzo Chemicals Amoco Chemical Arcadian Asarco Big River Zinc Boliden Intertrade Cargill Fertilizer CF Industries Chevron Chemical Citgo Petroleum Climax Molybdenum Coulton Chemical Cyprus Minerals Cytec Doe Run Dupont Chemicals El Dorado Chemical Farmland General Chemical

Plant location Fort Saskatchewan Redwater, AB Jonquie`re, QC Valleyfield, QC Transcona, MB Belledune, NB Key Lake and Rabbit Lake, SK Valleyfield, QC McClean Lake, SK Trail and Kimberly, BC Sudbury, ON Murdochville, QC Flin Flon, MB Beloeil, QC Coppercliff, ON Port Maitland, ON Kidd Creek, ON Varennes, QC Toronto, ON Fort Saskatchewan, AB Rouyn-Noranda, QC Fort McMurray, AB Elmira, ON Montreal East, QC Prince George, BC Calgary and Medicine Hat, AB Plant location Le Moyne, AL Texas City, TX Geismar, LA Three locations Sauget, IL Copperhill, TX Bartow and Riverview, FL Plant City, FL El Segundo, CA, and Honolulu, HI Lake Charles, LA Fort Madison, IA Cairo and Oregon, OH Claypool, AZ Fortier, LA Herculaneum, MO Six locations El Dorado, AR Pierce, FL Three locations

PERSPECTIVES ON SPECIFIC SUBSTANCES: SULFURIC ACID

American manufacturers IMC-Agro Jersey Miniere Zinc J R Simplot Kemira Kennecott Koch Sulfur Products Magma Copper Marsulex Mobil Mining and Minerals Nu-West Olin Hunt Speciality Products PCS Phosphates Peridot Chemicals Phelps Dodge Refining Public Service Co of New Mexico PVS Chemicals Rhone-Poulenc Basic Chemicals Rohm and Haas SFI Phosphates Southern States Tampa Electric Tosco Refining Unocal Chemicals U.S. Agri-Chemicals U.S. Army Zinc Corp. of America

35.15

Plant location Five locations Clarkesville, TN Lathrop, CA, and Pocatello, ID Savannah, GA Salt Lake City, UT Five locations San Manuel, AZ Sayreville, NJ Pasadena, TX Conda, ID Beaumont, TX, and Shreveport, LA Aurora, NC, and White Springs, FL Augusta, GA, and Newark, NJ Three locations Waterflow, NM Chicago, IL and Buffalo, NY Six locations Deer Park, TX Rock Springs, WY Savannah, GA Tampa, FL Martinez, CA Wilmington, CA Fort Meade, FL Radford, VA Bartlesville, OK and Monaca, PA

The major buyers in Canada are Abitibi-Consolidated, Alcan Smelters and Chemicals, Canadian Copper Refiners, Canadian Forest Products, Domtar, E.B. Eddy Forest Products, Explosive Technologies, Imperial Oil, Kimberly-Clark of Canada, MacMillan Bloedel, Procter and Gamble, Shell Canada, Scott Maritimes, and Weyerhaeuser Canada. The major buyers in the United States are AGP Refineries, Agrium, Air Products and Chemicals, Alabama River Pulp, Boise Cascade, Champion International, Consolidated Papers, Federal Paper Board, Georgia Pacific, Glatfelter, International Paper, Procter and Gamble, and Warren and Weyerhaeuser Paper. 35.4.3

Production and Transportation

In 1996, the total nameplate capacity for sulfuric acid in Canada was 5,681 kilotons and in the United States it was 36,306 kilotons. In 1993, the total global production of sulfuric acid was close to 135.3 megatons. Some growth is expected in the Middle East and North Africa. In Canada and the United States, sulfuric acid is transported primarily by rail and truck. Long-distance transport of sulfuric acid from smelters in remote locations makes freight costs extremely high.

35.5

CHEMISTRY Some of the chemical reactions often encountered during sulfuric acid spills are discussed here. One common element in all these reactions is the large quantity of heat that is given

35.16

CHAPTER THIRTY-FIVE

off. As these reactions are typically exothermic, some caution is required during emergency response operations and spill mitigation.

35.5.1

Neutralization

Like most strong mineral acids, sulfuric acid will react with bases to form salt and water. Therefore, substances such as slaked lime or sodium hydroxide are often added to sulfuric acid spills.

35.5.2

H2SO4 ⫹ 2 NaOH → Na2SO4 ⫹ 2 H2O

(35.5)

H2SO4 ⫹ Ca(OH)2 → CaSO4 ⫹ 2H2O

(35.6)

Reaction with Water and Hygroscopicity

Concentrated sulfuric acid is a strong dehydrating agent with an enormous affinity for water. It will extract water and elements of water from most materials, e.g., organic and inorganic with evolution of heat. Sometimes enough heat is generated to ignite surrounding combustible materials or vapor.

35.5.3

H2SO4 ⫹ H2O → H2SO4 䡠 H2O

(35.7)

(C6H10O5)X ⫹ H2SO4 → 6C ⫹ H2SO4 䡠 5H2O

(35.8)

Fire and Intense Heat

Sulfuric acid itself is not combustible, but under certain conditions, it can produce enough heat when reacting with other substances to ignite or decompose. 4 H2SO4 → 4 H2O ⫹ 2 SO2 ⫹ 2 SO3 ⫹ O2

35.5.4

(35.9)

Reaction with Metals

Under certain conditions, sulfuric acid can react with many metals to produce salt and flammable, explosive hydrogen gas. It will also corrode many materials to form innocuous substances. It will react with many sulfides, oxides, and carbonates.

35.5.5

2 Al ⫹ 3 H2SO4 → Al2(SO4)3 ⫹ 3 H2

(35.10)

2 Fe ⫹ 3 H2SO4 → Fe2(SO4)3 ⫹ 3 H2

(35.11)

FeS ⫹ H2SO4 → FeSO4 ⫹ H2S

(35.12)

Oxidation

Concentrated sulfuric acid is a strong oxidizing agent and can oxidize carbon, nonmetallic elements, and many metals. These reactions generally occur when the acid is in high concentrations and at high temperatures. The potential hazard of these reactions is due to the formation of sulfur dioxide, a toxic gas.

PERSPECTIVES ON SPECIFIC SUBSTANCES: SULFURIC ACID

C ⫹ 2 H2SO4 → CO2 ⫹ 2 SO2 ⫹ 2 H2O

35.5.6

35.17

(35.13)

Pb ⫹ 3 H2SO4 → Pb(HSO4)2 ⫹ SO2 ⫹ 2 H2O

(35.14)

Cu ⫹ 2 H2SO4 → CuSO4 ⫹ SO2 ⫹ 2 H2O

(35.15)

Hazardous Reactions

Sulfuric acid will undergo many double-displacement reactions to produce new substances that may be hazardous. These substances should therefore be stored at distant locations. 2 NaBr ⫹ 2 H2SO4 → Br2 ⫹ SO2 ⫹ NaSO4 ⫹ 2 H2O 3 NaClO3 ⫹ 3 H2SO4 → 3 NaHSO4 ⫹ HClO4 ⫹ 2 ClO2 ⫹ H2O 2 HClO4 → Cl2O7 ⫹ H2O

violent explosion

8 HI ⫹ 3 H2SO4 → H2S ⫹ 4 I2 ⫹ 4 H2O

35.6

(35.16) (35.17) (35.18) (35.19)

BEHAVIOR Sulfuric acid is a heavy, viscous, water-soluble, and very corrosive liquid. Although sulfuric acid is not a volatile substance, fuming sulfuric acid (referred to as oleum) is. Since it does not evaporate extensively, it is hard to detect by smell. Sulfate aerosols and mist may form in the atmosphere.

35.6.1

Terrestrial Fate

When spilled on land, sulfuric acid will settle for a few minutes before flowing away as it finds the lowest levels. It will sorb to the soil and char any vegetation with which it comes in contact. Because of its high viscosity, concentrated amounts will not rapidly leach into the soil unless it rains or other precipitation occurs. The process of soil acidification involves replacing exchangeable base cations such as calcium and magnesium with protons and aluminum ions. In other words, removing bases and mobilizing aluminum are the key processes. As sulfuric acid penetrates the soil, some of it will be neutralized by bases and carbonates, some will react with silicates and organic materials, some will exchange with metal cations, and the rest may leach into groundwater.

35.6.2

Aquatic Fate

If spilled into water, sulfuric acid will mix convectively and dissolve in the water column as it sinks. Vigorous turbulent mixing will occur as the sulfuric acid front advances, resulting in entrainment. As the entrainment grows, the density differences will become smaller. Two kinds of acid-spill scenarios can occur: (1) those in which no appreciable amount of acid aerosols are produced, and (2) those in which acid aerosols form and provide the major hazard. In both cases, large amounts of heat are liberated at the early stages of the spill. Examples of the first kind of spill are a capsized barge with all the hatches wide open and a gradual leak from a ship in a collision underwater. The second kind involves a spill of fuming sulfuric acid or oleum over water surfaces and shallow surface water. The heat released as a result

35.18

CHAPTER THIRTY-FIVE

of dilution provides latent heat, and the heat of vaporization produces acid mist of sulfur trioxide and water to form sulfuric acid. Sulfuric acid will also react with any bases and organic matter in the water. It has been shown that very low pH is extremely toxic to fish and aquatic organisms. 35.6.3

Study of a Sulfuric Acid Spill near Springhill, Nova Scotia

On December 13, 1978, a railway tank car of concentrated sulfuric acid (93%) was spilled as a result of a train derailment about 10 km northwest of the town of Springhill, Nova Scotia. The spill caused visible damage to vegetation over a limited area. In the fall of 1985, seven growing seasons after the spill, Environment Canada contracted MacLaren Plansearch Limited, in association with P. Lane and Associates Limited, to undertake a study to document the effects of the spill and make recommendations on appropriate response measures for future spills of sulfuric acid (Environment Canada, 1986). Some Environment Canada scientists were also involved in the research project. This spill and the results of the study are discussed in Section 35.8.2.

35.7 35.7.1

HUMAN AND ENVIRONMENTAL TOXICITY Effects on Humans

The most common types of injuries to people during spills of concentrated sulfuric acid are burns as a result of direct contact with this acid. These burns often cause marked scarring of the skin. The concentrated form of sulfuric acid destroys organic matter as a result of its severe dehydrating action. It is also a severe irritant to the eyes, respiratory tract, and skin. The respiratory system and teeth are usually damaged as a result of chronic exposure to the acid aerosols and mists. Accidental exposure to liquid fuming sulfuric acid can result in skin burns as well as pulmonary edema from inhalation. Pulmonary fibrosis, residual bronchitis, and pulmonary emphysema have also been reported. A single overexposure to sulfuric acid may lead to acute laryngeal, tracheobronchial, and pulmonary edema. Concentrations of around 5 mg / m3 have been found quite objectionable, often causing coughs and respiratory dysfunctions. The data in Table 35.2 summarize human responses to various levels of concentration of sulfuric acid mist. Investigations of respiratory effects of sulfuric acid during acute exposures, as in some spill cases, have had mixed results because there are many factors that influence its toxicity. These factors include particle size of the mist, humidity, presence of particulate, synergistic and protective agents, and preexisting conditions of victims (Amdur, 1989; Amdur and Chen, 1989; Linn et al., 1989; Lippmann, 1989; and Schlesinger et al., 1984). Bronchospasm in asthmatics has been shown to be a major concern. These effects are caused mainly by

TABLE 35.2 Human Responses to Sulfuric Acid Mist

Concentrations (mg / m3)

Response

0.5 to 2.0 3.0 to 4.0 6.0 to 8.0

Barely noticeable irritation Coughing, easily noticeable Decidedly unpleasant, marked alterations in respiration

PERSPECTIVES ON SPECIFIC SUBSTANCES: SULFURIC ACID

35.19

inhalation of the acid aerosols deposited on the surface of the respiratory tracts. The smallest aerosols (less than 10 ␮m) often cause the greatest alteration in pulmonary function because they can penetrate farther into the alveoli, whereas the larger particles are deposited in the upper respiratory tract. Increase in airway resistance at high acid concentrations has been demonstrated by several authors. Presence of ammonia in expired air has been reported to afford some protection in humans. Synergism has been demonstrated when sulfuric acid is deposited on zinc oxide dusts in the presence of sulfur dioxide, and also when combined with nitrogen dioxide or sulfur dioxide, ozone, metallic aerosols, and sulfuric acid. Chronic exposure of the teeth to the corrosive action of sulfuric acid as in battery acid workers has resulted in etching or total loss of teeth substance. A number of studies have also shown some association between chronic exposure to sulfuric acid and laryngeal cancer (U.S. Department of Health, Education and Welfare, 1974). For example, a 13-fold excess risk of laryngeal cancer was found among chemical refinery workers with the highest exposure, and a 4-fold risk was found for those moderately exposed, as opposed to very low exposure. Repeated exposures to sulfuric acid mists have been reported to cause dermatitis, stomatitis, conjunctivitis, and tracheobronchitis.

35.7.2

Animals

A considerable body of evidence exists on the sensitivity of laboratory animals to sulfuric acid. As discussed in Section 35.7.1, inhalation of sulfuric acid causes changes in pulmonary flow resistance, which are sometimes irreversible. These changes could be seen as the first stage of bronchitis. The smaller the particles (⬍2 ␮m), the more damage is done. The results of some animal studies are shown in Table 35.3.

35.7.3

Aquatic Species

The main cause of death of species in acid lakes is the excessive loss of sodium ions, which cannot be rapidly replaced by active transport. The disruption of sodium / potassium pump mechanism has been attributed to the presence of high concentrations of hydrogen ions.

TABLE 35.3 Effects of Sulfuric Acid on Animals

Concentration (␮g / m3), time

Species

Effects

100, 1 hour

Guinea pig

500, 1 hour

Dog

510, 1 hour

Guinea pig

1,000, 1 hour

Guinea pig

190 and 1,400, no time 1,000, 1 hour

Donkey Dog

Pulmonary resistance increased 47%, pulmonary compliance decreased 27%. Slight increases in tracheal mucociliary transport velocities immediately and one day after exposure. One week later clearance was significantly decreased. Pulmonary resistance increased 60%. Pulmonary compliance decreased 33%. Pulmonary resistance increased 78%. Pulmonary compliance decreased 40%. Bronchial mucociliary clearance was slowed. Depression in tracheal mucociliary transport rate persisted one week after exposure.

35.20

CHAPTER THIRTY-FIVE

TABLE 35.4 Effects of Acidity on Aquatic Organisms

pH

Effects

6 5.8

Crustaceans, molluscs, etc. disappear; white moss increases. Salmon, char, trout, and roach die. Sensitive insects, phytoplankton, and zooplankton die. Whitefish and grayling die. Perch and pike die. Eels and brook trout die.

5.5 5 4.5

In 1975, sulfuric acid was added to an experimental lake in Canada, causing the pH in the lake to drop from 6.8 to 5, which killed many fish species. Shrimp and minnows died at about pH 5.8, followed by the young trout. At pH 5.6, crayfish began to die as their exoskeletons lost their calcium and became infested with parasites. The sensitivities of aquatic organisms to the lowering of pH based on studies in Scandinavian lakes are summarized in Table 35.4.

35.7.4

Plants

Direct contact of concentrated sulfuric acid with plants will result in perforation of the plant tissue and the plant may subsequently die. The most common response of plants to acidic precipitation is low growth and the formation of foliar lesions or areas of dead tissue on the upper surface of the leaves. Necrotic spotting of the epidermis of the leaves after exposure to sulfuric acid mist has been reported in previous investigations. The effects of acid precipitation on plants are shown in Table 35.5.

35.8

SURVEY OF PAST SPILLS, LESSONS LEARNED, AND COUNTERMEASURES APPLIED Sulfuric acid is the most frequently spilled high-volume hazardous chemical in industry. Unlike spills of other chemicals, some spills are large, especially those that involve rail and ship transport. Spills from pipes, bottles, and cylinders are often small. While very few deaths have been reported as a result of these spills, respiratory distress is common.

TABLE 35.5 Effects of Acid Precipitation on Plants

pH

Plant

Effects

2.5 3.1 3.1 3.4 3.4 4.04

Bean Yellow birch Bean, sunflower Hybrid poplar Sunflower Bean

Foliar aberrations, decrease in growth Foliar lesions, decrease in growth Foliar lesions Foliar lesions Foliar lesions Reduction in dry weight

PERSPECTIVES ON SPECIFIC SUBSTANCES: SULFURIC ACID

35.8.1

35.21

Sulfuric Acid Spill at a CPR Train Derailment Near MacTier, Parry Sound, Ontario

On February 12, 1984, 14 railcars were fully derailed and another jumped the tracks, spilling sulfuric acid into Beers Lake, 29 km south of Parry Sound in Ontario. Each car contained 93 tons of sulfuric acid. Three cars went through the ice, 9 cars were on the bank leading to the lake, and 1 straddled the tracks. Four cars were leaking from the dome and 1 lost half its contents On the night of the spill, a pH reading of 6.5 was measured at the outlet of the lake. The next day, tests were taken across the lake and down the center and pH levels ranged from 5.0 to 6.0, with one location at 4.5. Officials at the scene believed that most of the acid remained on the shore and in the water nearest the accident. Emergency crews worked through the night to contain the spill. One outlet was blocked with sandbags to prevent any flow of acidic water. Three cars were offloaded during the night. The Canadian Transport Commission investigated a broken wheel as a possible cause of the derailment. Sampling and pH measurements continued as officials from the Ontario Ministry of the Environment monitored the spill. Work crews from the Canadian Pacific Railways (CPR) were dispatched and 15 cars of limestone were sent from Toronto and two truckloads from Sudbury to neutralize the acid spill. 35.8.2

Sulfuric Acid Spill Near Springhill, Nova Scotia

On December 13, 1978, an eastbound CN freight train travelling at approximately 40 mph (64 km / h) derailed close to Springhill, Nova Scotia. A total of 51 cars were derailed. One railway tank car containing concentrated sulfuric acid (93%) ruptured and almost its entire contents spilled. The acid pooled in a swale parallel to the south side of the tracks and flowed downslope along three distinct paths (one major, two minor). Most of the spilled acid flowed into an underground pit or cavity of unknown origin. Because of the highly fractured nature of the bedrock in the area, most of the acid that reached the pit quickly probably found its way into the groundwater, although no adverse effects on groundwater were reported. Overland flow of the acid was fairly restricted. Although the spill occurred at the top of a slope, eyewitnesses from Environment Canada (R. Simmons, L. Tripp) indicated that the three rivulets of acid flowed only partway down the slope. No acid reached the ditch on the north side of the highway at the bottom of the slope. The following factors may have contributed to this: 1. The amount of acid flowing overland was greatly reduced because most of it flowed into the underground cavity. 2. The surface materials on the slope were highly permeable. 3. Although it was early winter and the ground was lightly snow-covered, the ground was not yet frozen. This was confirmed by members of the spill response team, who indicated there was no frost in the ground when an emergency road was bulldozed to the site. The Environment Canada report on the spill indicated that a CN employee and a local resident were injured as a result of stepping in a pool of acid (Environment Canada, 1986). After the derailment, the priority was to restore service on the mainline. No action was taken to neutralize the spilled acid until a truckload of sodium hydroxide solution arrived on the site on December 14, 25 hours after the spill occurred. By the time the truckload of sodium hydroxide was pulled up to the trackside the following day, almost two days had passed since the spill. Neutralization was done selectively where pockets of acid could be reached. Sodium hydroxide was allowed to percolate through the new roadbed material to

35.22

CHAPTER THIRTY-FIVE

neutralize the acid underneath. Sgnificant amounts of sodium hydroxide were pumped into the cavity where much of the acid had flowed. (A solid block of sodium sulfate, the product of neutralizing sulfuric acid with sodium hydroxide, remains in the pit to this day.) The top of the slope where the spill occurred was severely impacted by physical disturbance associated with response to the spill. All of the natural vegetation was bulldozed and the site covered with up to 90 cm of sandy fill. Much of this fill remained almost barren of vegetation, which is the major long-term disturbance associated with the spill. The direct effects of the spill itself are relatively subdued after seven growing seasons. The ground vegetation in acidic areas is superficially indistinguishable from unaffected areas. Shrubs are reinvading areas where acid-induced shrub mortality was high. The main signs of the spill are the standing remains of dead shrubs. It is surprising that even after seven years all the spilled acid has not leached through. This clearly shows that the hydrogen ions are held in place by more than simple adsorption forces. Some effects on exchangeable soil minerals were also studied.

35.8.3

Sulfuric Acid Leak

In October, 1993, a 2.5-cm transfer line suddenly failed as workers were transferring sulfuric acid from a 3,785-L storage tank to a 378-L day tank (Loss Prevention, 1993). The leak caused an 18-m spray from where the leak occurred. A worker was sprayed by the acid mist, which penetrated his clothing and caused second-degree burns on his back. The victim was washed down in a shower and later taken to a medical facility for treatment. The bulk storage tank, which contained a 93% sulfuric acid solution, was connected to two tanks, the day tank and an acid regeneration tank (also called the dilute tank), by 2.5cm carbon steel lines. The valve in the line connecting the bulk storage tank and the dilute tank was located near the dilute tank. The acid spray was caused by a failure in the line where it was connected to the valve. The procedure for transferring acid from the bulk tank to the day tank required that the valve at the dilute tank be closed and a transfer pump be used to facilitate the transfer of acid from the bulk tank to the day tank. When the accident occurred, the valve at the dilute tank was closed and the transfer pump had been started. The pump built up pressure in the pipe, causing the acid to spray out. The failed line was constructed of carbon steel and appeared to be a Schedule 40 pipe, although the engineering drawings specified use of Schedule 160 pipe, which is about twice as thick. In addition, it was known that the flow of acid through the line normally reduces the thickness of the pipe wall by about 5 ␮m per year. The section of the line that failed was approximately 10 years old. As soon as the leak was discovered and the transfer pump shut down, the area was barricaded and thoroughly washed. All piping was subsequently inspected using nondestructive evaluation (NDE) techniques, and pipes of insufficient thickness were replaced. Lessons Learned The following lessons were learned from this incident: 1. When system components are replaced or repaired, all engineering documents must be checked to ensure that the correct materials are used. 2. A preventative maintenance program, including a replacement schedule, must be in place. Management must ensure that all hazardous materials and processes are identified and that procedures are developed and implemented to ensure safety. 3. Implementation of relevant standards related to mechanical integrity, procedures, and training would have prevented the use of incorrect schedule piping.

PERSPECTIVES ON SPECIFIC SUBSTANCES: SULFURIC ACID

35.8.4

35.23

Sulfuric Acid Spill in Richmond, California

In July 1993, 20 to 50 tons of fuming sulfuric acid spilled at the General Chemical Corp. plant in Richmond, California, a major industrial center near San Francisco. The release occurred when oleum was being loaded into a nonfuming acid railroad tank car that contained only a rupture disk. The tank car was overheated and this rupture disk blew. The resulting cloud of sulfuric acid drifted northeast with prevailing winds over a number of populated areas. More than 3,000 people subsequently sought medical attention for burning eyes, coughing, headaches, and nausea. Almost all were treated and released on the day of the spill. By the day after the release, another 5,000 people had sought medical attention. The spill forced the closure of five freeways in the region as well as some Bay Area Rapid Transit System stations. Health officials stated that most of the people affected would suffer no long-term effects from the exposure and that environmental effects would be minimal. Lesson Learned Again, a sound preventative maintenance program is crucial to eliminate such accidental spills.

35.9

CONCLUSIONS Sulfuric acid is an important substance that is widely used in industry. The effects of sulfuric acid spills are very localized, and evidence suggests that sulfuric acid and oleum do not constitute a serious threat to the Canadian public at large.

35.10

REFERENCES Amdur, M. O. 1989. ‘‘Sulfuric Acid: The Animals Tried to Tell Us,’’ Applied Industrial Hygiene, vol. 4, pp. 189–197. Amdur, M. O., and L. C. Chen. 1989. ‘‘Furnace Generated Acid Aerosols: Speciation and Pulmonary Effects,’’ Environmental Health Perspectives, vol. 79: pp. 147–150. American Industrial Hygiene Association (AIHA). 1988. Emergency Response Planning Guidelines, AIHA, Fairfax, VA. Bailar, J. C., H. J. Emeleus, R. Nyholm, and A. F. Trotman-Dickenson, eds. 1975. ‘‘Halides,’’ in Comprehensive lnorganic Chemistry, Pergamon Press, New York, NY, pp. 1124–1280. Budavari, S. 1989. The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals, 11th ed. Merck & Co., Rahway, NJ. Camford Information Services, Inc. (CIS). 1997. ‘‘Sulfuric Acid,’’ in CPI Product Profiles, CPI, Scarborough, ON. Duecker, W. W., and J. R. West, eds. 1959. The Manufacture of Sulfuric Acid, Robert E. Krieger, Huntington, NY, pp. 1–134. Environment Canada. 1986. Follow-up Study of Sulfuric Acid Spill Near Springhill, Nova Scotia. Environment Canada. 2000. National Air Pollution Surveillance (NAPS) Network—Annual Summary for 1998, Report EPS 7 / AP / 31, Environmental Protection Service, Ottawa, ON. Fingas, M., N. Laroche, G. Sergy, B. Mansfield, G. Cloutier, and P. Mazerolle. 1991. ‘‘A New Chemical Spill Priority List,’’ in Proceedings of the 8th Technical Seminar on Chemical Spills, Environment Canada, Ottawa, ON.

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Inco Limited. 1985. Sulfur Dioxide Abatement Project, Final Report-December 1988, Sudbury Smelter Complex, SO2 Emission Control Regulation 660 / 85, December 12. Kirk-Othmer Encyclopedia of Chemical Technology. 1983. 3rd ed., vol. 22, Wiley-Interscience, New York, NY. Linn, W. S., E. L. Avol, K. R. Anderson, D. A. Shamoo, R. C. Peng, and J. D. Hackney. 1989. ‘‘Effect of Droplet Size on Respiratory Responses to Inhaled Sulfuric Acid in Normal and Asthmatic Volunteers,’’ American Review of Respiratory Disease, vol. 140, pp. 161–166. Lippmann, M. 1989. ‘‘Background on Health Effects of Acid Aerosols,’’ Environmental Health Perspectives, vol. 79, pp. 3–6. Loss Prevention. 1993. ‘‘Acid Line Breaks—Worker Burns,’’ p. 4. Muller, T. L. 1997. ‘‘Sulfuric Acid and Sulfur Trioxide,’’ in Encyclopedia of Chemical Technology, 4th ed., ed. M. Howe-Grant, vol. 23, John Wiley & Sons, New York, NY, pp. 363-407. RRETCS On-Line. 1999. Registry of Toxic Effects of Chemical Substances, Department of Health and Human Services, Centers for Disease Control, National Institute for Occupational Safety and Health, Washington, DC. Schlesinger, R. B., L.-C. Chen, and K. E. Driscoll. 1984. ‘‘Exposure Response Relationship of Bronchial Mucociliary Clearance in Rabbits, following Acute Inhalations of Sulfuric Acid Mist,’’ Toxicology Letters, vol. 22, pp. 249–254. U.S. Department of Health, Education and Welfare. 1974. Occupational Exposure to Sulfuric Acid, Criteria for a Recommended Standard.