Coal is a combustible black or brownish-black sedimentary rock with a high amount of carbon and hydrocarbons. Coal is classified as a nonrenewable energy source because it takes millions of years to form. Coal contains the energy stored by plants that lived hundreds of millions of years ago in swampy forests. Layers of dirt and rock covered the ...

 · The acid-insoluble and alkali-soluble fraction from lignite coal is called humic acid and contains about 20–80% of the organic content in lignite [ 3 ]. Humic acid is also known as polyhydroxy carboxylates that include aliphatic and aromatic subunits [ 4 ].

 · PhD candidate Andrew Hood said raw low-rank brown coal naturally contains humic substances, including humic and fulvic acids, which are used in commercial soil additives. These organic acids are formed from the decomposition of plants.

 · It is rich in organic matter, including humic acids (HAs), which are involved in the accumulation of REEs.7Humic acids fraction doesn't contain silicates and is completely soluble in alkaline solutions, so it is assumed that REEs bound with humic acids could be more easily released.

The growth-promoting properties of coal-derived humus were tested by a variety of bioassay methods. Humate materials used included leonardite, a form of naturally oxidized lignite, and humic acids extracted from leonardite. It was found that the greatest effects were evident when water-soluble humic acid was applied to excised root tips.

 · (2011). Effects of Coal- Derived Humic Substance on Some Soil Properties and Bread Wheat Yield. Communications in Soil Science and Plant Analysis: Vol. 42, No. 9, pp. 1050-1070.

A method for mechanochemical activation of coal, which allows one to transfer up to 93 ± 7% REEs into the organic alkali-soluble fraction – the HA fraction (while HA in the pristine coal contain only 38 ± 3% REE) – has been developed. The estimated total concentration of REEs in pristine coal ash is 8000 ppm.

 · In this paper, the production of humic substances (HS) through the bacterial solubilization of low rank coal (LRC) was evaluated. The evaluation was carried out by 19 …

 · In this paper, the production of humic substances (HS) through the bacterial solubilization of low rank coal (LRC) was evaluated. The evaluation was carried out by 19 bacterial strains isolated in microenvironments with high contents of coal wastes. The biotransformed LRC and the HS produced were quantified in vitro in a liquid growth …

The estimated REE content in the ash of humic acids in MA coal is as high as 17 300 g per ton. Cerium concentration in this ash is about 6000 g per ton. For comparison, the Clarke value of cerium in coal ash is 130 g per ton.

Chemically, humic coals are characterized by hydrogen varying between 4% to 6%. Ref: Tomkeieff ii. Coals in which the attritus may be composed predominately of transparent humic degradation matter. ... Most seams of coal consist principally of humic coal and the technological properties vary with their rank, with their petrographic composition ...

 · LRC Characterization: the humidity of the LRC used in this study was 28.44%, 11.12% of the coal was ash, and 47.79% volatile substances. Similarly, the calorific power was 4781 Kcal.Kg −1, 41.09% of the coal had fixed carbon, and 0.13% of …

Bituminous coal contains 45%–86% carbon. Bituminous coal in the United States is between 100 million and 300 million years old. Bituminous coal is the most abundant rank of coal found in the United States, and it accounted for about …

Definition of humic coals i. A group of coals, including the ordinary bituminous varieties, that have been formed from accumulations of vegetable debris that have maintained their morphological organization with little decay. The majority of them are banded and have a tendency to develop jointing or cleat.

Humic acids (HA) are one of the main environmental factors controlling the fate and behavior of the compounds released into the environment. In particular, they are universally considered of great importance in determining soil extracellular enzyme activity and stability via association with essential soil enzymes. The objective of this study was to investigate …

 · However, it is rich in humic substances and has a variety of functional groups, such as carboxyl, hydroxyl, phenolic hydroxy thiol groups, etc., resulting in a high capability to enhance bioactivity. For instance, weathered coal can be used as a good natural adsorbent because of its adsorption, complexation and exchange properties [ 2 – 5 ].

 · Cleaning Coal with Coal:Coal Humic Acids for Removal of Acid,Iron,Heavy Metals,and Organic Pollutants Associated with Use of Coal as a Fuel. ：17 ...

The U.S. Department of Energy's Office of Scientific and Technical Information

 · coal There are two broad categories of coal humic- More common and originates from peat deposits consisting mostly of organic debris deposited in situ (autochthonous). sapropelic- Derived from redeposited (allochthonous) resistant plant fragments such as spores or aquatic plants. The sapropelic coals can be further …

The formation of humic acids (HAs) from bituminous coal was verified by laboratory oxidation. In a relatively short time the oxidation by air at temperature above 150 degrees C led to the formation of HAs. These HAs were compared with those isolated from oxidized bituminous coal from the vicinity of …

 · It contains about 45-86% carbon. Coal is a sedimentary rock, and bituminous coal frequently contains "bands," or strips, of different consistency that mark the layers of plant material that were compressed. …

However, the generally weathered bituminous coal contains a large amount of regenerated humic acid (HA) and a variety of oxygen-containing reactive functional groups, such as …

 · Preparing humic acids is considered to be an economic choice for the utilization of lignite. Herein regenerated humic acids (RHAs) have been obtained by means of hydrolysis of Chinese-aged lignite with NaOH as the catalyst. It has been verified that the hydrothermal process has enabled 67% increase in the extraction yield of humic acids …

 · Brown coal is one of the richest sources of humic substances [ 1 ]. The production of humic acids and humin-containing materials from brown coal is a promising alternative to its energy generation use [ 2 ], and it belongs to the field of deep processing oriented to the integrated development of fossil coals [ 3 ].

 · In the UV–Vis spectra of coal-derived humic acid (Fig. 2a), the peak observed at around 220–300 nm is due to the π→ π* transition of π -electron of the aromatic groups present in coal-derived humic acid (Das et al. 2013, 2015, 2017a, b).Similar results were also obtained after recording the UV–Vis spectra of standard humic acid as shown in Fig. …

The formation of humic acids (HAs) from bituminous coal was verified by laboratory oxidation. In a relatively short time the oxidation by air at temperature above 150 degrees …

 · The initial alkali extraction of acid-washed coal was carried out five times. In three cases the humic acid was isolated (12 1 wt.% db coal yield) and in two cases …

 · Young coal contains a lot of organic acids called humic acids, which chelate metals and rare earths. But over time, the humic acid concentrations in coal drop, and the rare earths get incorporated into aluminosilicate clays. Once the rare earths are associated with the clays instead of humic acid, they are harder to extract.