Search results for "tuhka"
showing 10 items of 13 documents
Selective recovery of phosphorus as AlPO4 from silicon-free CFB-derived fly ash leachate
2018
The prospect of phosphorus (P) recovery from siliceous fly ash was investigated. The phosphorus content in the pristine fly ash was 1.21%. Obtaining pure phosphorus products from fly ash is very challenging because of high concentration of other elements, silicon (Si) at 17.3% being the major contaminant. The fly ash was fractionated with sieve size of 125 μm to concentrate the phosphorus in the small-size fraction, which also facilitated the removal of 78% of silica (Si) in the solid phase. The fractionated fly ash was treated with 8 M HCl in order to remove 98% of Si by aging (5 h) of leachate until precipitation of Si-gel, and a phosphorus-rich solution is obtained. Iron (Fe) is also con…
Occurrence and recovery potential of rare earth elements in Finnish peat and biomass combustion fly ash
2019
Rare earth elements (REEs) are highly important in the modern society as a result of their wide use in various fields of industry. Their high supply risk and increase in demand has led to classification as critical materials, and consequently, new resources for REEs are being prospected widely. Coal fly ash has been suggested as a possible secondary resource for REEs, but very little information is available regarding REE occurrence in biomass or peat derived fly ash. In this paper, fly ash samples from commercial power plants using peat and biomass as fuel were studied for REEs. The average concentration of REEs was 530 ppm, with up to 920 ppm in one fly ash. Five out of seven fly ashes we…
Lannoitevalmisteiden tuottaminen biojätteistä, puhdistamolietteistä, rejektivesistä sekä lentotuhkista : esimerkkinä Jyväskylän seutu
2012
Tässä tutkimuksessa tarkasteltiin Jyväskylän seudulla muodostuvista jätevedenpuhdistamoiden lietteistä ja rejektivesistä sekä biojätteistä, lannoista ja lentotuhkista tuotettavissa olevia lannoitevalmisteita. Tiedot raaka-aineiden määristä ja ominaisuuksista koottiin pääosin alueellisesta jätteenkäsittely-yhtiöstä, jätevedenkäsittely-yhtiöstä sekä energiayhtiöstä. Osa raaka-aineiden ominaisuuksista arvioitiin kirjallisuusarvojen perusteella tai määritettiin laskennallisesti. Jätevedenpuhdistamoiden lietteiden sekä biojätteiden ja lantojen tuotteistamismenetelmiksi valittiin anaerobinen hajotus sekä kompostointi ja terminen kuivaus. Rejektivesien ammoniumtypen talteenotossa vertailtiin strip…
The determination of antimony and arsenic concentrations in fly ash by hydride generation inductively coupled plasma optical emission spectrometry (H…
2011
Hydride generation inductively coupled plasma optical emission spectrometry (HG-ICP-OES) was used in the determination of As and Sb concentrations in fly ash samples. The effect of sample pre-treatment reagents and measurement parameters used for hydride generation was evaluated. Due to memory effects observed, the appropriate read delay time was adjusted to 60 s resulting in RSDs 0.6% and 2.3% for As and Sb, respectively. The most suitable volumes of pre-reduction reagents for 10 mL of sample were 4 mL of KI/ascorbic acid (5%) and 6 mL of HCl (conc.). The determination of Sb was significantly interfered by HF, but the interference could be eliminated by adding 2 mL of saturated boric acid …
Control of matrix interferences by multiple linear regression models in the determination of arsenic and lead concentrations in fly ashes by inductiv…
2010
A multiple linear regression technique was used to evaluate and correct the matrix interferences in the determination of As and Pb concentrations in fly ashes by inductively coupled plasma optical emission spectrometry. The direct determination of As and Pb in SRM 1633b by ICP-OES failed to obtain the certified concentrations, except in a couple of cases. However, it proved possible to use the multiple linear regression (MLR) technique to correct the determined concentrations to a satisfactory level. This method of correction is based on the multiple regression line obtained from the analysis of 19 synthetic mixtures of matrix and analyte elements (Al, As, Ca, Fe, Pb, and Si) at five concen…
The Use of Ca- and Mg-Rich Fly Ash as a Chemical Precipitant in the Simultaneous Removal of Nitrogen and Phosphorus - Recycling and Reuse
2019
The European Union’s circular economy strategy aims to increase the recycling and re-use of products and waste materials. According to the strategy, the use of industry waste material should be more effective. A chemical precipitation method to simultaneously remove phosphorus and nitrogen from synthetic (NH4)2HPO4 solution and the liquid phase of anaerobic digestate using fly ash as a precipitant was tested. Fly ash is a waste material formed in the power plant process. It mainly contains calcium oxide (CaO) and magnesium oxide (MgO). Saturated precipitant solution was prepared from fly ash, which was added in small proportions to (NH4)2HPO4 solution during the experiment. Fly ash’s effect…
Characterisation and treatment of waste incineration bottom ash and leachate
2012
Development of ultrasound-assisted digestion methods for the determination of toxic element concentrations in ash samples by ICP-OES
2011
The present thesis introduces several ultrasound-assisted digestion methods developed for the determination of toxic element concentrations in ash samples by inductively coupled plasma optical emission spectrometry (ICP-OES). Ultrasound-assisted digestion is a quite new technique used for sample pre-treatment purposes, especially in difficult sample matrixes. Elements determined are As, Ba, Co, Cr, Cu, Ni, Pb, Sb, Sr, V, and Zn. Most of the elements determined exist at a trace or ultra trace level in ashes and most are potential risks in the environment or human body even at low concentrations. Most of the selected elements can be determined directly by ICP-OES, but for the determination of…
The determination of trace element concentrations in fly ash samples using ultrasound-assisted digestion followed with inductively coupled plasma opt…
2009
A method of ultrasound-assisted digestion followed by inductively coupled plasma optical emission spectrometry (ICP-OES) used for the determination of trace element (chromium, copper, lead, nickel, vanadium and zinc) concentrations in fly ash samples was developed. All the measurements were performed in robust plasma conditions. Ultrasound-assisted digestion procedures using digestion solutions of aqua regia and hydrofluoric acid (HF) resulted in recovery rates of over 80% for all the analyte elements. Ultrasound-assisted two-step digestion with digestion solutions of 6 mL of HNO₃(Step 1) and 3 mL of HNO₃+ 3 mL of HF (Step 2) resulted in recovery rates of over 92% for all the analyte elemen…
An ultrasound-assisted digestion method for the determination of toxic element concentrations in ash samples by inductively coupled plasma optical em…
2007
method of ultrasound-assisted digestion followed by inductively coupled plasma optical emission spectrometry (ICP-OES) used for the determination of toxic element concentrations (arsenic, barium, cobalt, copper, lead, nickel, strontium, vanadium and zinc) in ash samples was developed. All the measurements were performed in robust plasma conditions which were tested by measuring the Mg(II) 280.270 nm/Mg(I) 285.213 nm line intensity ratios. The highest line intensity ratios were observed when a nebulizer gas flow of 0.6 L minˉ¹, auxiliary gas flow of 0.2 L minˉ¹ and plasma power of 1400 W were used for radially viewed plasma. The analysis of SRM 1633b showed that the ultrasound-assisted metho…