Coke plant processes…

- “For over 130 years, a glowing night sky signified the presence of iron and steel making furnaces operating in Johnstown. The valley’s fortunes depended on how red those skies glowed at night.” (From Berger, Karl. Johnstown, the Story of a Unique Valley. Johnstown Flood Museum, 1985. )

The mining of bituminous coking coal in the United States was done primarily in the Appalachian coal region. Regions of Alabama, Kentucky, Pennsylvania, Virginia, and West Virginia were typically the largest suppliers of coking coal. In Pennsylvania, Cambria County was one of the only counties in the bituminous coal region in Pennsylvania which had four important coal deposits with the uppermost being the Gallitzin seam, then the Lower Freeport seam, the Upper Kittanning seam, and the Lower Kittaning seam. The Lower Kittaning, or sometimes referred to as the Miller or “B” seam, was consistently worked in mines throughout the county as it produces a low volatile, high fixed carbon, low moisture coal which consistently can produce a high grade of coke.

Most of the coke produced in the United States was specifically for the iron and steel industries. Coke plants were normally situated in areas where suitable coking coal was available and usually they were as close as possible to the coal-source areas for economic reasons. The deep underground mine in the Hinckston Run stream valley (Lower Kittanning seam; Rosedale # 72) was such an example and the early operations of the Cambria Iron Company in the late 19th century were fortunate to have large amounts of coal in proximity to the two coking plants in Johnstown - one at Franklin and the other at Rosedale. Eventually this phased out as more suitable as processes improved and more suitable coal and iron ores from other places were used.

Coke = a refined form of coal in which impurities are removed by baking and which leaves nearly pure carbon - a fuel capable of generating intense heat.

Coal processing in the iron and steel industry typically involved producing coke, coke gas, and by-product chemicals from compounds released from coal during the coke-making process. Coke-making and iron-making preceded steel-making. Coke is a complex solid produced by heating coal in the absence of oxygen at high temperature for complete combustion in coke ovens by a process known as carbonization. Coke in it’s final form is carbon-rich and was used as a fuel to heat and melt iron ore for iron and steel-making. The material is gray-black to silvery gray in color and of a porous and brittle nature and which produces intense heat without smoke when it is burned. Thus perfect for mass iron and steel production.

According to general industry information, coke production in the United States increased steadily between 1880 and the early 1950s, peaking at 72 million tons in 1951. In 1976, the United States ranked second in the world in coke production, producing 52.9 million tons, or about 14.4 percent of the world’s supply. In 1990, United States production was 27 million tons, fourth highest worldwide. Production gradually declined from 22 million tons in 1997 to 16.8 million tons around 2002. Demand for blast furnace coke declined because technological improvements reduced the amount of coke consumed per amount of iron/steel produced by a range of 10 to 25 percent. A 1977 United States Environmental Protection Agency (US EPA) study of human population exposures to coke oven atmospheric emissions rated the Bethlehem Steel Corporation (BSC) Rosedale Division coke plant as having an annual coal capacity at 550,000 tons and a 1974 coal consumption rate at 545,000 tons.

The following will describe the complexity of the coking process in general terms. After suitable coal was mined and processed - usually by crushing and washing (it is said that the washery at the Rosedale coke plant had combined capacity of 350 net tons per hour) - processed coal was then it was transported by conveyor belts to storage bins at the coke oven plant location. The coke-making process started with a bituminous pulverized coal “charge” which was fed into the coke oven through ports in the top of the oven. Coal was usually transported from the storage bins to the ovens by a lorry. A lorry was a small coal car that ran on rails on/along the roof on the back half of the coke ovens. The lorry then moved along the rails to the oven that was to be charged. A charge was about 7 tons of processed coal that was dumped into a trunnel head. The trunnel head was an opening in the roof of the oven. After charging, the oven ports were sealed. The opening on the front of the oven was walled in with bricks after the oven was charged. A small space was left at the top of the bricks to regulate the amount of air in the oven. A yellow-red mud, prepared by hand, was then used to fill open spaces between the bricks. A small amount of coke breeze (fines) was used in the mixture to make it stick more effectively.

The coal was then ignited in the (Wilputte and Semet-Solvay) coke oven and heated to very high temperatures, in some cases 1,600 to 2,300 degrees F, and in the absence of oxygen. Coke manufacturing was done in a batch mode where each cycle lasted for 14 to 36 hours. A coke oven battery consisted of a series of 10 to 100 individual ovens, side-by-side, with a heating flue between each oven pair. After the coal was carbonized, the brick door was physically broke open and water was sprayed over the hot coke and left to cool for about a half hour. Volatile compounds that remained from the coal-to-coke process was collected from each oven and processed for recovery of combustible gases and other coal by-products.

Historical Note: The Rosedale coke plant was erected in 1919. Between then and 1922, more batteries of coke ovens were added to the “new” plant creating 208 ovens in all. Average production in historical records indicate output at the Rosedale coke plant at 3,800 tons per day. One ton equals two thousand pounds.

The solid carbon remaining in the oven was the coke. Then a tool called a beaver bar was used to pull the coke from the oven. The coke was then typically shoveled into flatbed wheelbarrows and transported and dumped onto elevated mechanical belt conveyors that then loaded it into hopper rail cars. The coke was then transported by the hopper rail cars to an adjacent processing plant where it was further crushed, screened, and sized. It was then ready for use to make iron or steel in a blast furnace.

Before the days of the more modern direct-arc electric blast furnace (EAF), which became operational in Bethlehem’s operation in Johnstown in late 1981, the basic oxygen furnace (BOF) was primarily used for iron or steel-making. Coke was needed to make iron or steel in this type of blast furnace. Pig iron was produced by heating the coke, iron ore, and limestone in the blast furnace. Coke for smelting of iron ore in blast furnaces was required to meet very particular specifications as to its physical qualities and composition and was specially produced in a coke oven plant from carefully selected types of bituminous coal.

As with most community and industrial system processes, by-products are created that must be dealt with or disposed of. In the coke oven by-products recovery process, volatile components of the coke oven gas stream were recovered including oven gas itself (which was used as a fuel for the coke oven), naphthalene, ammonium compounds, crude light oils, sulfur compounds, and coke breeze (fines). During the coke quenching (cooling), handling, and screening operation, coke breeze was produced. Typically, coke breeze was reused in other manufacturing processes on-site (e.g., sintering) or sold off-site as a by-product.

Historical Note: As indicated previously, I was born and raised on Benshoff Hill/Valley View section of south Middle Taylor Township. Based on my research, Benshoff Hill is involved in some of the earliest history of steel making in Johnstown. According to Pages 258 and 259 in Chapter 10, Iron and Steelmaking in the Conemaugh Valley by Richard A. Burkett with George Hand, from the awesome book Berger, Karl. Johnstown, the Story of a Unique Valley. Johnstown Flood Museum, 1985 the following is noted:

“In some places in the valley, geologists found three veins of coal and three of iron alternating at elevations well above the water line. Discovery of the native iron ores is credited to George S. King, a successful Johnstown merchant, who began explorations in the late 1830’s which resulted in the location of iron ore beds close to Johnstown. Coursing the hillsides, digging test wells and talking to farmers about soils, King and his partner, Samuel Kennedy, ranged the valley in their quest for metal. In 1840 a test well, 37 feet deep, yielded a fifteen inch vein of iron. This first discovery was made about four miles from Johnstown, on the John Seigh farm along Laurel Run in West Taylor Township. King took several tons of the ore to Ross Furnace, northwest of Ligonier, where it was smelted into pigs. The raw iron later was forged and rolled into rods and bars. The Laurel Run iron made excellent bar iron but it was too brittle unless mixed with more malleable metals. Based on the success of these tests, King and Kennedy bought the Seigh farm. In 1843 the vein was traced into adjoining lands. Digging into Prospect and Benshoff’s Hill, the miners extracted red carbonate ores from beds 18 to 30 inches thick.”

Coke plant contaminants…

Coke-making was viewed by experts as one of the processes within the iron and steel making industry of greatest environmental concern - with air emissions and quench (cooling) water creating being the most significant. These two areas of concern are explained in more detail below.

Air Emissions

Typical coke-making air emissions included ammonia, benzene-soluble organics, benzene, particulates, sulfur oxides SOx, and volatile organic compounds VOCs. Coke plant operators have initiated significant efforts to control these emissions and have spent millions of dollars on environmental control systems, improved operating and maintenance practices, and increased personnel training. These efforts have substantially reduced coke-making air emissions over the last three decades.

Coke-oven air emissions are known to be human carcinogens based on sufficient evidence of carcinogenicity from studies in humans. These emissions are complex mixtures of dusts, vapors, and gases that typically include polycylclic aromatic hydrocarbons (PAHs), formaldehyde, acrolein, aliphatic aldehydes, am­monia, carbon monoxide, nitrogen oxides, phenol, cadmium, arsenic, and mercury. More than 60 organic compounds, including more than 40 PAHs, have been identified in air samples collected at coke plants. Chemical analyses of coke-oven emissions revealed the presence of numerous known carcinogens and potentially carcinogenic chemicals, including several PAHs, nitrosamines, coal tar, arsenic compounds, and benzene. In addition, coke-oven air emissions contain several agents known to enhance the effect of chemical carcinogens, especially on the human respiratory tract. Workers at coking plants and coal tar production plants, as well as people who lived near these plants, had a high risk of possible exposure to coke-oven emissions.

Wastes and By-Products

Several RCRA listed wastes were produced during coke-making operations. These coke-making process wastes were: tar residues; oils; naphthalene residues; lime sludges; wastewater sump residues containing benzene and polynuclear aromatic hydrocarbons (PAH’s); and coke oven gas condensate from transfer and distribution lines.

The typical volume of process wastewater generated at a well-controlled coke plant was approximately 150 gallons per ton of coke produced (EPA 2000). About 25 to 35 gallons per ton were generated as waste ammonia liquor from moisture contained in the charged coal. The remaining balance was from the steam used in distilling ammonia from the waste liquor, light oil recovery, and other processes. Coke-making wastewater contained significant levels of oil and grease, ammonia, nitrogen, cyanides, thiocyanates, phenols, benzenes, toluene, xylene, other aromatic volatile components, and polynuclear aromatic compounds. Wastewater also contained trace amounts of toxic metals like antimony, arsenic, and selenium. The amount of each pollutant generated depended on the by-product process, specific facility equipment, practices, and the range of constituents in the coal that was used.

In the by-product coking process, volatile components were collected as un-purified “foul” gas containing water vapor, tar, light oils, coal dust, heavy hydrocarbons, and complex carbon compounds. Condensable materials, such as tar, light oils, ammonia, and naphthalene were removed, recovered, and processed as gas and coal chemical by-products. Finally, sulfur was removed, leaving clean, de-sulfurized coke oven gas. The cleaned, de-sulfurized gas was then used as fuel for coke ovens or other plant combustion processes, or it was sold to nearby facilities.

Seven (7) listed hazardous wastes are associated with coke-making under the RCRA. These wastes include residues from coal tar recovery; tar storage tanks; light oil processing units; wastewater sump residues; and naphthalene collection and recovery. Process residues from coal tar recovery were generated when un-condensed gas entered a primary cooler. Condensates from the primary cooler flowed into a tar collecting sump and was discharged in a flushing liquor decanter. Tar collection sump residue or sludge accumulated at the bottom of the collecting sump, and needed to be recycled periodically as an individual stream, through the flushing liquor decanter, or back to the coke oven. Tar storage tank residues were produced when residuals settled out of the crude coal tar collected as a coking by-product.

The residues were periodically removed from the storage tanks and were recycled to the oven or land-filled. Residues from light oil processing units were collected in a light-oil scrubber and light-oil stripping still. Resin is a related waste that accumulated from cleaning wash oil used in the light-oil recovery process. Wash-oil muck, residue from a wash-oil purifier or decanter, was periodically removed and recycled to the coke oven, reclaimed off-site, or used as blast furnace or boiler fuel. Wastewater sump residues accumulated in the bottom of a sump and sufficient quiescent residence time was provided for oil and water to separate during light oil recovery. These settled solids were removed periodically and either recycled to the oven or land-filled off-site. Residues from naphthalene collection and recovery accumulated at the bottom of a skimmer sump where naphthalene was mechanically skimmed off the surface. Residues also accumulated in the hot and cold sumps used as collection or surge vessels and on cooling tower surfaces. It was normally recycled to the decanter or sometimes the oven.

Polycyclic aromatic hydrocarbons (PAH’s) are formed in the coking process from the heating of coal in the absence of oxygen. The PAH emissions from coke ovens were partially gaseous with another portion of the PAHs associated with fly ash particles and soot and with tars or pitches that formed as a consequence of cooling and re-condensation processes used during off-gas treatment. Coke by-product plants produced tar and other materials with high levels of PAHs. Not surprisingly, the ground surface in the vicinity of coke ovens and a coke by-products plant were often highly contaminated with PAHs and the cleanup of such sites is/was a major challenge for Brownfield remediation. (Note: For more about Brownfield programs, see the “Conclusion” portion of this website)

It can be assumed that normal operations at the Bethlehem Steel Corporation (BSC) Rosedale coke plant during the operational period from the early to mid 20th century were not too efficient. Operations during that time focused on production and profit, not environment protection. In the later decades of the 20th century (1970’s and 1980’s) and because of clean air legislation until closure and razing of the plant, it can be assumed that the operations were much more efficient and compliant. But air and water pollution existed at/from this plant as well as from coal refuse and slag waste materials which were taken up the Hinckston Run valley for dumping at the Riders Dump (Rosedale) Disposal Area. Although soils at the actual BSC Rosedale coke plant site footprint later were “remediated” under various Brownfield Redevelopment grant programs (for more on Brownfields see the “Conclusion” portion of this website), contaminated coal refuse and waste slag and soils that were transported and dumped at the Riders (Rosedale) Disposal Area for several decades were not. Such contaminants eventually worked their way into surface waters and the groundwater table within the Hinckston Run stream valley.

In a 2011 report by AccelorMittal USA LLC, which was the industrial entity that assumed control of the former plant properties, Page 64 stated the following: “We own a large former integrated steelmaking site in Johnstown, Pennsylvania. The site has been razed and there are a number of historic waste disposal units, including solid and hazardous waste landfills located at the site that are subject to closure and other regulation by PaDEP. There are also historic steel and coke-making operating locations at the Johnstown site that may have caused groundwater contamination. Although subject to RCRA corrective action or similar state authority, no comprehensive environmental investigations have been performed at this site to date.” This quotation from that report is a pretty stunning yet factual statement.

Note: The Rosedale coke plant had a lot of incredible and just downright fascinating history to it. A 1922 industry article explained some of the plant technologies used at that time. The article also included other specifics about the Rosedale and Franklin plant operations. It states how coal was retrieved from the Hinckston Run valley and also gives information about the 208 ovens that were present at the Rosedale coke plant. A copy of portions of that article is here:

Coal refuse…

Appalachian bituminous coal was mined from nearby deep mines within the hillside of the Hinckston Run stream valley and other nearby areas to feed the Bethlehem Steel Corporation (BSC) Rosedale coke plant. For decades prior to any recent site remediation activities at the site of the Riders (Rosedale) Disposal area (reclamation, capping, settling and treatment basins, etc.), this site was a long-standing coal refuse disposal area exposed to the environment.

Coal refuse is comprised of rocks and minerals unavoidably removed from the earth’s subsurface during the coal mining process and from leftovers from small amounts of coal that was not separated during processing. Most local folks were/are familiar with and can recognize the many coal refuse piles scattered across the landscape in Cambria and neighboring counties of Western Pennsylvania. Many of these piles have been reduced greatly in number and size over the last 20 or 30 years due to re-use activities such as from several co-generation power plants in the area that utilize circulating fluidized bed (CFB) combustion technology to burn low quality refuse waste coal. Two of these plants are located in Ebensburg. Another one is located in Colver. More recently many of these co-generation power plants are converting from use of coal refuse to natural gas - like the newer CPV Fairview Energy Center facility in nearby Jackson Township.

Dominant elements in coal are carbon, hydrogen and oxygen. Impurities present in coal are nitrogen, sulfur, iron and other various organics. Sulfur, an impurity of significant importance, occurs in three principle forms in coal. The forms include organic sulfur, sulfate sulfur, and pyritic sulfur. Pyrite is probably the most significant of the forms. Iron and sulfur impurities are also common in many coal-bearing sedimentary rocks. As with coal itself, the most significant of these impurities are the pyrites.

Coal refuse facilities can substantially degrade the quality of water in nearby water resources if they are not constructed or controlled properly. In the early to mid parts of the 20th century, it can be assumed that proper construction and best management practices were not implemented at the Riders (Rosedale) Disposal Area site.

In addition to adversely impacting surface waters, like the Hinckston Run stream, runoff and drainage from coal refuse disposal areas like at the RIders (Rosedale) Disposal Area, can also pollute groundwater sources below the ground surface. Water pollution problems created from some coal refuse disposal sites can be very serious. Coal refuse leachate (ie. seepage) is most often quite acidic and corrosive in nature and contains elevated levels of trace metals such as iron, aluminum, and manganese. When quantities of leachate enter a surface water such as a stream, aquatic habitats are significantly impacted and desirable aquatic organisms are usually reduced, altered or eliminated entirely. When quantities of leachate percolate (seep) into the ground and groundwater sources below the ground surface, aquifers can become polluted. Drinking water consumed from these sources can cause serious health problems in humans.

Acidic drainage is also quite common from coal refuse disposal sites. Most local folks were/are also familiar with and can recognize the many coal refuse pile and acid mine drainage seeps present around Johnstown and all across Cambria and neighboring counties of Western Pennsylvania. Iron disulfides occurring either as pyrite or marcasite are integral components of coal refuse. Their oxidation (coming in contact with both air and water) produces compounds that are quite acidic and water soluble. Thus, drainage and percolation of water over and through a coal refuse area produces a leachate that contains high concentrations of sulphuric acid and various metal salts that are quite toxic to aquatic organisms.

Quote - “And if ever the chemists are able to filter out of mine drainage all its sulphurous content, Johnstown people may once more be able to enjoy the sport of fishing.” (From Berger, Karl. Johnstown, the Story of a Unique Valley. Johnstown Flood Museum, 1985, Chapter 14 History of Planning in Johnstown by Edwin T. Pawlowski; City Planning Commission, Hornbostel & Wild comprehensive planning report from 1917. )