Lignite States

North America.. In the United States, lignite deposits are located in the northern Great Plains and in the Gulf states. Subbituminous coal is found along the Rocky Mountains. The western half of North Dakota has about 74% of the nation s resources, Montana 23%, Texas 2%, and Alabama and South Dakota about 0.5% each. The lignite resources to 914 m represent 28% of the total toimage of all coal deposits in the United States. The lower cost and low sulfur content have contributed to rapid growth in production. 

The lignitic coals of the northern United States tend to have low sulfur contents, making them attractive for boilet fuels to meet sulfur-emission standards. However, low sulfur content coals have impaired the performance of electrostatic precipitators. The ash of these coals tends to be high in alkaline earths (Ca, Mg) and alkaUes (Na, K). As a result, the ash can trap sulfur as sulfites and sulfates (see Airpollution control methods). 

In the United States, the most desirable lignites for wax production are those from California and Arkansas. A yield of ca 7% is obtained from these lignites those from other states give only about 2%. 

Lignite. Deposits generally classified as unconventional uranium resources occur in lignite and in clay or sandstone immediately adjacent to lignite. Examples are uraniferous deposits in the Serres Basin, Greece, North and South Dakota in the United States, and Melovoe in the CIS (17) (see... 

Montan Wax. Montan wax [8002-53-7] is derived by solvent extraction of lignite (qv). The earliest production on a commercial scale was in Germany during the latter half of the nineteenth century, and Germany continues to supply the majority of the world s production of montan wax. Montan wax production at Amsdorf is part of a massive coal-mining operation from a continuous vein and raw material is expected to last for decades. Montan wax is also produced in the United States. Imports of montan wax into the United States for the years 1990—1995 are Hsted in Table 1. Germany suppHes over 80% of the montan wax imported into the United States (3). 

World coal usage, inclusive ot the three major types of coal—anthracite, bituminous (by far the most prevalent form) and lignite—reached a plateau in the first decade of the twentieth centuiy and climbed only very slowly in the half century that followed. By 1880, coal use had equaled wood use on a worldwide basis. The usage around the turn of the centuiy was on the order of 2.2 gigatons per year (around 55 quads), of which about 600 million tons were in the United States. World oil production progressively supplemented the use of coal between 1900 and 1950, increasing by more than an order of magnitude in that period of time, from a little over a quad to some 20 quads. Coal s increase over those years was fractionally much less. 

In absolute terms, the quantities of reactor solids found in various processes do vary considerably. The rate of accumulation is related to several factors, such as coal characteristics, recycle solvent quality and reactor design. However, it can be stated in general terms that liquefaction of low rank coals (sub-bituminous C and lignites) does result in higher rates of accumulation of solids than do similar operations with bituminous coals. For example, during normal operations of the SRC-I pilot plant at Wilsonville, Ala., it has been found that the amount of solids retained varies from about 0.2-0.5 wt.% (moisture-free) for bituminous coals to 1.0-1.9 wt.% (moisture free) for a subbituminous C coal (Wyodak) (72). Exxon also reports much larger accumulations for lignites and subbituminous coals than those found for bituminous coals (73). 

All the coalified wood samples examined in this report were of lignite rank, as determined by their elemental compositions (Table 1). The one sample from the Moscow Basin was not analyzed for its elemental composition but was collected from a well-known Carboniferous lignite deposit. Figure 1 shows the solid-state 13c NMR data for some of the samples. Though the spectra show a large, broad... 

Figure 1. Solid state NMR spectra of lignitic wood samples.

Figure 1. Location of the four lignite deposits in south eastern South Australia in relation to the state capital (Adelaide).

Large Data Set. LTAs were analyzed by FTIR for 50 coals, ranging in rank from lignite to Ivb. These were a representative subset of 95 unwashed and clean commercial coals from the eastern, mid-western and western United States and Alberta, Canada. The 50-coal set contained no duplicate coal samples, but different coal samples from the same mine were included. 

Dr. Garcia was supported by a postdoctoral fellowship provided by the Spanish Research Council (CSIQ. Financial support for the experimental work was provided by The Pennsylvania State University Cooperative Program for Coal Research, llie authors are grateful fcH the sample of yhiran lignite provided by the Istanbul Technical University. 

Processes and equipment for the gasification of inferior coke and chars from low-temperature carbonization of subbituminous and lignitic coals were developed in Germany (13), where the relatively large yield of low-temperature tar was welcomed as raw material for hydrogenation processes. The market for low-temperature tar in the United States has been too small and the selling price too low to encourage the use of low-temperature chars for gas production. 

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