AN EFFICIENT EXTRACTION PROCESS FOR THE PRODUCTION OF HUMIC GOLD USING LIGNITE
Field of Invention
The embodiments herein generally relates to application of humic acid in agricultural field. Specifically, the embodiments described herein relate to crops yield improvement by using humic acid.
Background of the Invention
Humic acid is naturally occurring organic substance found more in forest soil and rich in oxidized low rank coal, lignite, peat, etc. 90 % of humic acid largely constituent of Carbon and Oxygen. Humic substances arise from chemical and biological degradation of plant and animal residues and from the synthetic activities of micro-organisms. They are dark coloured, acidic, predominantly aromatic, hydrophilic, and chemically complex. Humic acid increases water retention, retain nutrients and enhance microbiological activity - enzymes in soil. The organic matter on biodegradation converted into humus, which contains humic & fulvic substances. The humic substance contains various functional groups of Carboxylic, Carbonyl, Phenolic, alcoholic with higher molecular weight of 40,000 to 70,000. Higher cation exchange capacity (100 - 130 me/100 gm). Lignite contains around 60% of humic acid -which is a plant growth stimulant and beneficial to crops. There is a significant improvement in the yield of various crops on using humic acid besides improving the quality of agricultural produce. Composition of Humic Acid is given below in Table 1. Table 1: Composition of Humic Acid
Element C H O N
Humic acids 52 - 62 3.0 - 5.5 30 -33 3.5 - 5.0
(% in dry ash free basis) On the basis of solubility in acids and bases, humic substances are differentiated into the Humins, Humic and Fulvic acids. These forms are in a state of dynamic equilibrium. Humins are more condensed form of humic acid, even though there may be a few structural differences among them. Humins are highly complex forms in which they are known to help the soil particles to form aggregates. The Fulvic acids are the simplest forms, which are known to be absorbed by plants. Beneficial effects of Fulvic chelate complexes oh crop plants have been .well established. Humic acids are intermediate in complexity between

humins and fulvic acids. But their molecular weights have a wide range. Humic acids with high molecular weight are not known to be assimilable, while the low molecular weight humic acids are said to be assimilable by the plant. Beneficial, physiological effects of humic acids on several crops have been observed under nutrient solution culture, which is subject to rapid fluctuations such as pH and nutrients imbalance. Hence such favourable effects of humic acids on crop appeared to be more indirect than direct. Humin, the alkali, insoluble part of organic matter represents the high molecular fraction of humic substances.
It has complex organic molecules formed by the breakdown of organic matter in soil. They are the main fraction, the biological center, of natural humic matter. In general, soil contains around 2 % organic matter and about 0.3 % humic acid. Humic acid is found more in forest soils and peat (2-10 %). It is rich in oxidized low rank coal, and lignite (40-60 %). Lignite is rich in humus matter. The major component of humic acid is carbon and oxygen and is about 90 %. Due to intensive cultivation, organic matter and other nutrients were depleted from soil. To compensate this, traditionally organic manure, compost, vermi-compost and green manure are used in large quantities to raise organic matter in soil to achieve humic acid content. Application of humic acid helps to build up organic matter status in soil and also it enhances water retention and cation exchange capacity. Humic acid is applied to the crops in the form of basal application, foliar spray, furtigation, root dipping, seed coating, etc.
It is mainly used for agricultural applications and is an approved organic farming input by Organic.Materials Review Institute, USA. Humic acid in general is extracted from low rank coal lignite with alkaline solution. This invention provides an improved and efficient method for extraction of potassium humate from lignite as raw material.
Prior Art & Present Art
The history of investigation on humic matters could date back to 9th century. Initial data on humus formation from plant and animal residues are found in the works of Wallerius and Lomonosw in 1761-63 and the effect of humus matter on yields in Komows works (1782) Achard (1786) was probably the first Scientist who extracted humic matters from peat. Saussre found out for the first time that humic matters mainly consisted of carbon and to a lesser extent hydrogen and oxygen. Systematic investigations of humic matters were carried out by Spenyel (1825-1837) and Beizellus (1833 ID 1839). Development of scientific knowledge on the role of humic matters was initiated by Liebig (1840). Grandeau (1872) developed a new thecny of organic mineral plant nourishment and determined the importance

of capability of exchange and sorption of humic matters. Significant contributions to the knowledge of chemistry of humic matter in peat were made by Fischer and Schrader as well as by Fuchs by study of functional groups and humic matters decomposition products. But production and application of humic matters for agricultural purposes have not been made till the beginning of this century. Utilization of coal and beneficiated products from these has been investigated during the past sixty years. Both coal and lignite contain humic matter and lignite is richer in this respect. Earlier, crude coal or lignite was used as such as fertilizers, But in view of the slow activity of the humus matter and also the large quantity required per hectare of land (10 to 20 t/ha) this type of application was abandoned long ago. Subsequently enrichment of coal by mixing with ammonia solution, ammonium acetate, super phosphate, phosphoric acid, potassium salts etc. had been used and the nutrient values of the product were enriched to about 2.5% nitrogen, 1.3% phosphorus pentoxide, 2.1% potassium oxide and the total organic matter at 55%. In France, a number of lignite based fertilizers is produced and utilized. For many years some 2,50,0001 /year of lignite based fertilizers have been produced out of lignite imported from West Germany. In Yugoslavia, a technology was developed for the production of organic fertilizers out of lignite by adding superphosphate and ammonia to coal. But obtaining of higher amount of nutrient, particularly nitrogen from lignite was attempted in USA by.the oxidation of coal / lignite by nitric acid and neutralizing the product with ammonia. The product, ammonium nitro humate fertilizer contained 8-14% nitrogen according to the degree of purification. Oxidation and ammoniation of naturally occurring Leonardite and lignite also has given a nitrogen content of 8%. Investigations on these lines have been conducted in India also. Traditional agriculture based on organic manure, is not however target-oriented and in addition organic manure are not available in adequate quantities. It is well known that soil should have certain inherent properties that will help it adapt and assimilate the input nutrients and release the same for plant growth. Organic matter-is most important tool for such an activity. Thus humus matter in soil serves to stimulate the plant growth. These conditions have necessitated the application of humus mater extracted from coal, peat and lignite.
Investigations on the possibilities of utilizing coal, peat lignite and younger brown coals and products derived from it as fertilizer were carryout for the past 80 years. In Yugoslavia, academicians, V.Vouck tested right back in 1928 the action of some of the countries-coals on the pot cultures he operated on. In the studies he determined a favourable action of coal. The requirement of coal per hectare was as high as 10 tonnes in order to obtain a favourable effect. It was latter abandoned because of the high handling cost. In order to

reduce the quantity, coal / lignite was mixed with ammonium solution, ammoniates, super phosphates, phosphoric acids, various other phosphates, potassium salts etc.. Such coal based fertilizers were developed in Germany, USSR, France and Yugoslavia. In all the above processes there was no change in the structure of coal / lignite.
One group of Engineers attempted to bind a higher amount of nitrogen to coal / lignite by oxidation process with nitric acid and the subsequent neutralization with liquor ammonia. Acid action primarily increases the content of humic acid by destruction of existence of humates. The excess quantity of nitric acid caused, nitro humic acid. In some cases the oxidation was carried out with air and hydrogen peroxide. Detailed Description of Production of Humic Acid
In Centre for Applied Research and Development (CARD) Neyveli Lignite Corporation of India Limited (NLCIL), humic acid is extracted from lignite. The lignite contains about 50-60 % of humic acid. Lignite is used as a raw material for the production of Humic Acid as Potassium Humate. The extraction of humic acid was done by treating lignite with a base preferably NaOH and neutralization with HC1. It is then dissolved in K.OH to get potassium humate, which is one of the soluble forms of humic acid. The above process proved commercially not viable because it requires NaOH and KOH besides some pollution problem due to NaCI and HCI. The invention provides an improved and efficient method for making potassium humate from lignite as raw material. The invention provides an improved and efficient method for making potassium humate from lignite as raw material. The mined out Lignite having moisture of 40-55% is taken and air dried to reduce the moisture level to 10-25 % and used as raw material. Then it is pulverized to less than 1 mm using a Pulveriser. 5 to 30 % of pulverized lignite is mixed with 70 to 95 % of solution containing 0.5 to 3 % of Potassium hydroxide. The contents are allowed to react at a range of temperature 85-95° C, for about a period of 2 to 3 hours with continuous stirring or as and when required, so that the material is in suspension. The required process temperature is to be maintained by external steam heating. The pH (9 to 10) of the medium is to be adjusted continuously during the process, to obtain desirable extraction. After the digestion period the solution is to be agitated for uniform dispersion for about 2 to 3 hours. Then it is transferred to a settling tank for separation of final sludge. After 24 hours the clear solution obtained is made up to required concentration of 3.5-4.5 %. After checking pH and correction (9 to 10) it is transferred to main storage tank. The un-reacted lignite portion is discarded. Process flow & Schematic diagram of production is given below in Fig. 1 & 2

Different Field trial results are given below, by way of illustration of the working of the invention which should not be construed to limit the scope of the present invention.
Example 1
Only with Humic Acid: The product potassium humate has been tested in the fields and the results obtained in terms of yield for the crops are given below in the Table 2 & 3.
Table 2: Biometric Observations- Effects of Humic Acid on Yield of Different Types of Crops

Example 3
International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) - Humic Acid -On Farm Trials is given below in Table 4.
International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) : Humic Acid - On Farm Trials
The International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) is an ■ International organization which conducts agricultural research for rural development, headquartered in Hyderabad, Telangana, India with several regional centers and research stations. Foliar application of Humic acid has been evaluated in various districts of Andhra Pradesh, Telangana, Karnataka and Maharashtra by ICRISAT. These trails were conducted on farmers' fields and ICRISAT research station. Experimental sites represent different agro-climatic conditions & crops. Results from the on-farm as well as on-station trails clearly indicate the beneficial effect of foliar application of humic acid on crops and vegetables. At most of the location increase yield ranging from 6-34% has been recorded and the results are given below in Table 4.

The non-limiting advantages of the present invention are given below:
Humic substances impart a dark brown colour to the soil that influences the warmth of the soil. The soil structure and the stability of the structure are promoted by the richness of the humus in the soil. Water retentivity and air-water relationship in the soil are governed by the amount of humus in the soil. Humus serves as a reservoir of plant nutrients and it also prevents the leaching of plant nutrients because of its high cation exchange capacity. A soil rich in humus is known to have good buffering capacity so as to prevent sudden fluctuations in soil pH. Humus is known to form chelate complexes with trace element nutrients such as

iron and zinc which are rendered more easily available to the crop plants. As the humus undergoes mineralisation, organic forms of nitrogen, phosphorus and sulphur turn into inorganic forms which are utilized by the crop plants.
Crop-Product Quality
♦ Pulses: Protein and methionine contents were also improved
*t* Groundnut: Enhancing pod yield, shelling percentage, crude protein and
oil content. Sugarcane: Improved quality characteristics of juice viz., juice
%, brix %, purity % and CCS %. ♦t* Cotton: Cotton fiber quality fineness, bundle strength, and elongation
percentage improved *> Tomato: Increasing the total soluble solids, titratable acidity, sugar and
protein contents of fruits with a reduction in starch content.
♦ Onion: TSS, ascorbic acid, pyruvic acid, total sugar and crude protein -contents of onion bulb were also improved
♦ TAPIOCA: Recorded the maximum starch (31.5%) and protein (2.35%) contents.
♦> TEA: Higher yield of green leaf tea ( 10608 kg ha-1) -:

We Claim
1. A process for extraction of humic acid from lignite which comprises the steps of;
(a) The raw lignite is air dried and crushed to less than 1 mm by using pulveriser mill. This powdered lignite is added to 0.5 to 3 % weight by volume of Potassium hydroxide solution prepared in the reaction vessel and mixed at 25 to 30 revolutions per minute to get a uniform suspension.
(b) Mixture prepared as in step (a) is heated to a temperature of 85 to 95° C by conventional method and maintaining the temperature for further duration of 2 to 3 hours in the reaction vessel to solubilise the lignite to extract humic acid and the pH of the solution is maintained continuously around 9 to 10.
(c) The solution obtained in step (b) is transferred to a settling tank to separate any un-reacted material by conventional method and the clear liquid solution is transferred to the storage tank.
(d) The clear solution obtained in step (c) is a liquid with 3.5 to 4.5 % potassium
humate and pH 9 to 10. In the present improved process, one step eliminated
in the present process i.e., instead of converting liquid into solid material.
Liquid is used directly in the field applications which are more convenient and
user friendly.
2. Process as claimed in claim I wherein the Potassium Hydroxide solution of concentration 0.5 to 3 % weight by volume is used in step 1(a).
3. Process as claimed in claim 1 wherein lignite of size less than I mm with moisture content of about 10 to 25 % is added in step 1(a).
4. In the present process liquid form of highly solubilised i.e., more than 50 % of dissolved solids is prepared for direct applications without drying.
5. The process as claimed in claim 1 wherein approximately 20 kg of Potassium „ Hydroxide flakes is added to about 1800 to 2800 lit. of water and mixed well to get a clear solution. To that solution about 200 kg of air dried lignite with moisture content about 10-25 % is added. Heated to 85 - 95 ° C by external steam heating and maintained at that temperature for a further duration of 2 to 3 hours. The digested material is allowed to settle in the settling tank to separate any un-reacted material. The clear liquid containing 3.5 to 4.5 % potassium humate is stored in storage tank.
6. Process for extraction of humic acid from lignite is substantially as herein described and exemplified.

7. Using 1 tonne of lignite from 9,000 to 12, 000 liters of humic acid were produced.
8. Liquid has appreciable concentration of solubilised substances of about 50 % which can suitable for 25 times or more dilution and compatible for many agriculture crops applications such as soil as basal application, as top dressing by admixing with sand or organic manure or fertilizer, foliar spray, root dipping/ root feeding, mixed with irrigation water and also by using drip irrigation as fertigation.
9. Measured significant increasing yields in the range of 6 to 34 % with enhancing quality of the products.