Programmed dry ashing

The apphed pretreatment techniques were digestion with a combination of acids in the pressurized or atmospheric mode, programmed dry ashing, microwave digestion and irradiation with thermal neutrons. The analytical methods of final determination, at least four different for each element, covered all modern plasma techniques, various AAS modes, voltammetry, instrumental and radiochemical neutron activation analysis and isotope dilution MS. Each participating laboratory was requested to make a minimum of five independent rephcate determinations of each element on at least two different bottles on different days. Moreover, a series of different steps was undertaken in order to ensure that no substantial systematic errors were left undetected. 

Twelve laboratories from seven European countries participated in the certification (see section 6.1.4). The techniques of final determination used are summarised in Table 6.1. The pretreatment methods were digestion with a combination of acids in a pressurised or atmospheric mode, programmed dry ashing, combustion or irradiation with thermal neutrons [2]. A second group of laboratories additionally determined the contents of... 

Twenty three laboratories from eleven European countries participated in the certification campaign (see section 6.6.4). Table 6.16 summarises the different techniques of final determination used by these laboratories. Pretreatment techniques were digestions with combination of acids including HCIO4 and HF, in a pressurised or atmospheric mode, Kjeldahl pretreatment, programmed dry ashing and oxygen combustion. Other methods hardly used any pretreatment (e.g. INAA). 

Electrical energy is used almost exclusively for the drying, ashing, and vaporization steps in flameless atomization. In commercially available instrumentation these steps are programmed sequentially, with each step in the process being adjustable. Readout of the analytical signal can be either... 

After acid treatment, the dried ash was further activated with CO2 at 990°C in a programmable Lindberg Blue M tube furnace. The furnace was programmed to increase the temperatme at 50°C/min. Once the required temperatme was achieved a long horizontal column with ID of... 

Projects in the CCT program demonstrated innovative applications for both wet and dry or seniidry FGD systems. The wet FGD systems, which use limestone as an absorber, have met or exceeded the 90 percent SO, removal efficiency required to meet air quality standards when burning high-sulfur coal. The di"y or semidry systems use lime and recycled fly ash as a sorbent to achieve the required removal. 

The next experiments are conducted on a 500-pound-per-hour combustor. This combustor, which simulates commercial practice, is shown in Figure 2. It is a wall-fired, dry-bottom unit which uses cyclone ash collection. Where possible both coal and ash samples are obtained from commercial power plants to verify the results from the experimental combustors. The combination of the two programs will hopefully give... 

Analyses of Anthracites Used. For most of the experimental work an anthracite from the St. Nicholas breaker was used. Its proximate analysis (dry basis) was as follows C, 84.3% V.M., 4.5% ash, 11.2%. Anthracites from other breakers used in this program had the following volatile matter contents... 

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