Proximate and ultimate analyses, high and low heating values, and types of sulphur

Moisture content by indirect gravimetry is defined as the loss of mass until constant weight. Samples are heated to 107 ° C in an oven under nitrogen or air atmosphere.
The determination of moisture content in coals, solid biofuels and recovered solid fuel is carried out according to the Standards ISO 5068 , UNE- EN 14774-3 and UNE-EN 15414-3 respectively.
The service is equipped with a Thermoelectrón- Heraeus oven which allows working until 150ºC with circulation air / nitrogen.
Moisture content in liquid fuels is determinated by Xylene method. In this method is determinated by direct titration the water content of the sample by distillation in a water immiscible medium (Xylene ) to a temperature higher than boiling water .

Volatile content is defined as the mass loss (minus moisture ) when 1 g sample is heated to 900ºC for 7 minutes.
The determination of content volatile in coals, solid biofuels and recovered solid fuels is performed according to ISO 572, UNE -EN 15148 and UNE -EN 15402.
The laboratory is equipped with a CRN -48 dee Hobersal oven, desiccator with CaCl2 and Balance Sartorius BP.

Análisis elemental
Análisis elemental

Ultimate analysis is defined as the determination of carbon, hydrogen, nitrogen and sulfur in different materials, such as coal, solid biofuels, recovered solid fuels, ash, graphite, liquid fuels, nanotubes, carbon fibers, zeolites, steel, etc.
This determination is performed in a Thermo Flash 1112 which produces complete combustion of the sample within a high temperature reactor followed by an accurate determination of the elemental gases produces.

Calorímetro isoperibólico IKA C-2000

The high heating value is defined as heat (cal / g or kcal / kg ) released when burning a gram of fuel in a calorimeter (closed container).
The low heating value is defined as heat (cal / g or kcal / kg ) released when burning a gram of fuel in an open system.
The ICB has isoperibolic calorimeter IKA C-2000 which allows the determination of the high heating value in coals, biofuels solid, recovered solid fuels, liquid fuels and black liquor .
The ICB can determine the heating value from the data immediately, elementary and high heating value analysis according to ISO 1928 standards for coal, UNE -EN 14918 for solid biofuels and UNE -EN 15400 for recovered solid fuels.


Sulfur can be found in coal as sulfate, as pyrite and within the organic part. Given their different characteristics, properties and behaviour during combustion is interesting to quantify each of these species.

The ICB has developed, according to international standards ASTM and ISO, the procedures to analyze each of them.
Thus the total sulfur can be determined by elemental analysis or by the Eschka method (ASTM D 3177) which consists in breaking the sample with a mixture of magnesium oxide and sodium carbonate in a ceramic crucible at 815º, the subsequent extraction of the sulfates produced with water, pH adjustment and precipitation with barium chloride, filtration, calcination, barium sulfate weight and calculation of the %St.
The sulfur in the form of sulphates is determined according to international standards (ASTM D 2492) by its solution by boiling the test sample in hydrochloric acid, filtration. oxidation, solution of iron (II) to iron (III), precipitation with ammonia and removing the latter by filtration, adjusting the pH of the obtained solution and barium chloride precipitation, filtration, calcination, resulting barium sulfate weight and calculation of% S sulfate.
The pyrite sulfur is determined according to international standards (ASTM D24932), from hydrochloric acid residue obtained in the determination of sulphate sulfur, pyrite breakage with nitric acid, iron released determination by ICP, AA or valorization and calculation of the pyritic S content..