The influence of process parameters on coal desulfurization by nitric leaching

Bioassay of chemically treated subbituminous coal derivatives using Pseudomonas putida F1

“…Similar results were found by Sakanishi et al (2002). Nitric acid has also been shown to be effective at removing sulfur via desulfurization, particularly for inorganic sulfur such as pyrite (Rodriguez et al, 1996(Rodriguez et al, , 1997. Calcium, Mg Na, and K were shown to be the major species resulting from the catalyzed hydrogen peroxide pretreatments.…”

“…Nitric acid has been used to reduce both the inorganic and organic sulfur content of coal concomitant with coal solubilization, particularly under more energetic conditions (Alvarez et al, 2003;Rodriguez et al, 1996Rodriguez et al, , 1997. Other researchers have used nitric acid to modify the structure and composition of coals and convert them into organic fertilizers by increasing their humic acid content, the carboxylic acid content of the humic substances, and nitrogen content (Moliner et al, 1983).…”

“…Numerous studies have been performed to investigate the structure of coal and evaluate desulfurization, gasification and other processes (Alvarez et al, 2003;Burke et al, 1990;Deno et al, 1981;Hayatsu et al, 1981;Ike et al, 2011;Mae et al, 1997;Miura, 2000;Miura et al, 1996;Moliner et al, 1983;Palmer et al, 1994;Pignatello et al, 2006;Rodriguez et al, 1996Rodriguez et al, , 1997Yang et al, 1985). However, there has been little published information concerning the use of chemical reagents to pretreat subbituminous coals for the purpose of enhancing formation of biogenic natural gas.…”

Demineralization of low grade coal – A review

“…Rodriguez et al [123] concluded that nitric acid leaching of Spanish coal at atmospheric pressure is effective for desulfurization of intermediate-rank coal, especially for inorganic sulfur removal. In another study [143], it was found that most of the sulfur reduction takes place during the first 5 min.…”

“…Some of the chemical demineralization processes which have been investigated, include leaching with NaOH [112], NaOH followed by mineral acids [113][114][115][116][117], KOH-acids [115,118], Na 2 CO 3 [119], Ca(OH) 2 followed by acid washing [120], mineral acids viz. HNO 3 [121][122][123], HCl [116], H 2 SO 4 [124,125], oxidizing agents viz. H 2 O 2 [23,125], Fe 2 (SO 4 ) 3 [126], K 2 Cr 2 O 7 [127], NaOCl [128], HF [129], HF then HNO 3 [29,130] and sequential leaching by NaOH-H 2 SO 4 [131].…”