Positive synergistic effect of the hazardous waste use for secondary lead metallurgy, energy efficiency and waste minimization

Modification and optimization of the pyrometallurgical process of lead recovering from the waste lead-acid batteries have been studied in this paper. The aim of this research is to develop a cleaner production in the field of the secondary lead metallurgy. Lead smelting process with the addition of flux (sodium(I)-carbonate) and reducing agents (coke, iron) has been followed. The modified smelting process with the addition of hazardous waste (activated carbon) as alternative reducing agents has shown positive results on the quality of the secondary lead, the generated slag and the process gases. Filtration efficiency of the gases, the return of baghouse dust to the process and use of oxygen burners have positive effect on the environment protection and energy efficiency. Optimization of the recycling process has been based on the properties of the slag. Stabilization of slag is proposed in the furnace with addition of waste dust from the recycling of cathode ray tube (CRT) monitors. Phosphorus compounds from dust reduce leachability of toxic elements from the generated slag. Reduction the slag amount and its hazardous character through the elimination of migratory heavy metals and valorization of useful components have been proposed in the patented innovative device - cylindrical rotating washer/separator

Stabilization/solidification process of alkali lead waste slag: influence of pretreatment and addition of selected additives

More than 90% of lead produced in Europe comes from secondary lead flows, of which 85% is attributed to waste lead-acid batteries (LAB). The main technological approach for LAB processing implies pyrometallurgy by which 100–400 kg of waste slag (WS) is generated per 1 ton of produced metallic lead. Due to recycling process parameters, generated WS has great potential for releasing toxic elements contributing to environmental pollution [1]. Namely, the most common flux in the recycling process is sodium-based (Na2CO3) when alkali lead waste slag (ALWS) is generated, characterized as hazardous due to its physical-chemical characteristics: high leachability, hygroscopic and pulverized nature and, ultimately, instability [2,3]. Therefore, ALWS treatment prior to disposal should be considered an integral part of waste LAB treatment systems. Immobilization of toxic elements contained in slag is crucial and can be achieved by stabilization/solidification processes (S/S) as one of the most widely used technologies in the treatment of heavy metal-containing wastes for final disposal or utilization. In this research, ALWS generated in the waste LAB recycling is used to determine the S/S process efficiency as a function of the added binder amount (cement, in the range of 5 – 10 %), pre-treatment (the removal of water-soluble compounds), and activator addition (MgO). The liquid to solid (L/S) ratio was 1/4 in all S/S experiments. The basic parameters for the effectiveness assessments were compressive strength (UCS) and pollutants leaching (Method 1311 Toxicity characteristic leaching procedure, TCLP). ALWS containing 3.5 Pb, 15.5 Na, 14.0 S, and 24.7 Fe was mixed with cement and water. The results of UCS showed that all produced solidificates exceeded the required value of 0.35 MPa [4], yet the mixture containing 7.5 % of the cement has the best mechanical properties (2.1 MPa). This sample was further analyzed and the TCLP results showed that the Pb concentration exceeds the limit values for stabilized slag (10.4 and 5 ppm, respectively). In the next set, ALWS was pre-treated by continuous rinser (30 ºC, 60 min, L/S 4). Obtained results of UCS (0.4 MPa) and TCLP (53.4 ppm) were unfavorable. The last set, besides the binder, included activator addition (MgO, 7.5 %) altogether with a high content of untreated ALWS (85 %). Analysis of the produced solidificates showed favorable and acceptable results (USC - 3.3 MPa, TCLP – Pb 4.5 ppm). Generally, in an alkaline slag-leaching solution lead precipitates as a complex mixture (PbO, Pb(OH)2, PbO×Pb(OH)2). Lead oxides are amphoteric and dissolve in an alkaline aqueous solution, leading to poor solidification. Also, lead present in surface coatings around cement grains prevents cement hydration. Simultaneously, the migration of lead to the surrounding water is promoted. The negative effect of the pre-treatment is a consequence of the sulfate ions absence, as well as the absence of the ettringite (Ca6Al2(SO4)3(OH)12×26H2O) and sulfate- AFm phases [5], which negatively affect the strength of the product. The addition of MgO benefits the S/S process through hydrotalcite-like phase formation ([M1- 2+M 3+(OH) ][A n-×mH O], M2+=Mg, Zn, Ni, Fe; M3+=Al, Cr, Fe; A=CO 2-, NO -, Cl-), a compound capable of metal adsorption, hence immobilization [6]. The conclusion is that, contrary to the pre-treatment process, the addition of MgO has an overall positive effect on the S/S process of ALSW, ensuring both mechanical and chemical stability. This ALWS solidificate, obtained through the S/S process by using MgO as an activator, is safe for disposal, according to environmental regulations

Tehnološki postupak tretmana otpadnih voda nastalih na proizvodnom kompleksu „EcoMet Reciklaža“ d.o.o. u Zajači

Tehničko rešenje pripada oblasti ekstraktivne metalurgije i zaštite životne sredine, a odnosi se na razvoj tehnološkog postupka tretmana otpadnih voda sa povišenim sadržajem metala, koje nastaju na proizvodnom kompleksu za proizvodnju sirovog, rafinisanog i legiranog olova, prerade sekundarnih sirovina na bazi olova i oksidnog olovnog koncentrata u Zajači. Inovativnost Novog tehničkog rešenja koje je izrađeno za Tehnološki postupak tretmana otpadnih voda nastalih na proizvodnom kompleksu „EcoMet Reciklaža“ d.o.o. u Zajači se ogleda u kombinovanoj primeni tehnike hemijskog taloženja metala u obliku hidroksida sa primenom prirodnog zeolita u tretmanu otpadnih voda prilikom čega dolazi do istovremene modifikacije zeolita Fe(III) jonima i efikasne adsorpcije zaostalih metala iz rastvora. Primena ovakve inovacije u prečišćavanju otpadnih voda dovodi do višestrukog poboljšanja tretmana: - Postiže se efikasno uklanjanje restvorenih metala na pH vrednostima nižim nego što je zahtevano metodom taloženja hidroksida. - Generišu se manje količine stabilnijeg sekundarnog mulja usled prisustva zeolita. - Koristi se isti reagens (so gvožđe(III)-hlorid, FeCl3) za modifikaciju prirodnog zeolita i koagulaciju već nastalih čvrstih čestica taloga. - Izbegava se upotreba skupih jonoizmenjivačkih smola koje bi u ovom slučaju bile neophodne zbog prisustva arsena i antimona u otpadnoj vodi. Takođe, primenom Novog tehničkog rešenja prevazilaze se nedostaci konvencionalnih metoda prečišćavanja otpadnih voda: - smanjena upotreba ekonomski neispaltivih reagenasa, - smanjenje broja procesnih koraka i nivoa prečišćavanja i - primena ekonomski isplativog minerala zeolita, dostupnog u R. Srbiji koji omogućava efikasno vezivanje velikog broja katjona i oksoanjona As i Sb

Stabilization/solidification process of alkali lead waste slag: influence of pre-treatment and addition of selected additives

More than 90 % of lead produced in Europe comes from secondary lead flows, of which 85 % is attributed to waste lead-acid batteries (LAB). The main technological approach for LAB processing implies pyrometallurgy by which 100–400 kg of waste slag (WS) is generated per 1 ton of produced metallic lead. Due to recycling process parameters, generated WS has great potential for releasing toxic elements contributing to environmental pollution [1]. Namely, the most common flux in the recycling process is sodium-based (Na2CO3) when alkali lead waste slag (ALWS) is generated, characterized as hazardous due to its physical-chemical characteristics: high leachability, hygroscopic and pulverized nature and, ultimately, instability [2,3]. Therefore, ALWS treatment prior to disposal should be considered an integral part of waste LAB treatment systems. Immobilization of toxic elements contained in slag is crucial and can be achieved by stabilization/solidification processes (S/S) as one of the most widely used technologies in the treatment of heavy metal containing wastes for final disposal or utilization. In this research, ALWS generated in the waste LAB recycling is used to determine the S/S process efficiency as a function of the added binder amount (cement, in the range of 5 – 10 %), pre-treatment (the removal of water-soluble compounds), and activator addition (MgO). The liquid to solid (L/S) ratio was 1/4 in all S/S experiments. The basic parameters for the effectiveness assessments were compressive strength (UCS) and pollutants leaching (Method 1311 Toxicity characteristic leaching procedure, TCLP). The conclusion is that, contrary to the pre-treatment process, the addition of MgO has an overall positive effect on the S/S process of ALSW, ensuring both mechanical and chemical stability. This ALWS solidificate, obtained through the S/S process by using MgO as an activator, is safe for disposal, according to environmental regulations

Positive synergistic effect of the reuse and the treatment of hazardous waste on pyrometallurgical process of lead recovery from waste lead-acid batteries

Modification and optimization of the pyrometallurgical process of lead recovering from the waste lead-acid batteries have been studied in this paper. The aim of this research is to develop a cleaner production in the field of the secondary lead metallurgy. Lead smelting process with the addition of flux (sodium(I)-carbonate) and reducing agents (coke, iron) has been followed. The modified smelting process with the addition of hazardous waste (activated carbon) as alternative reducing agents has shown positive results on the quality of the secondary lead, the generated slag and the process gases. Filtration efficiency of the gases, the return of baghouse dust to the process and use of oxygen burners have positive effect on the environment protection and energy efficiency. Optimization of the recycling process has been based on the properties of the slag. Stabilization of slag is proposed in the furnace with addition of waste dust from the recycling of cathode ray tube (CRT) monitors. Phosphorus compounds from dust reduce leachability of toxic elements from the generated slag. Reduction the slag amount and its hazardous character through the elimination of migratory heavy metals and valorization of useful components have been proposed in the patented innovative device - cylindrical rotating washer/separator. http://dx.doi.org/10.5937/metmateng1403171

Conteptual design for treatment of mining and metallurgical wastewaters which contains arsenic and antimony

This paper presents a preliminary design for treatment of mining and metallurgical wastewaters (MMW) from the basin of antimony “Zajača“, which contains high concentrations of arsenic and antimony. MMW have been investigated in laboratory, due to large difference in concentrations of pollutants. Metallurgical wastewaters were treated using iron (II)-sulfate and lime milk used to adjust the pH value at 7. After chemical treatment of metallurgical wastewater and its joining with mining wastewater, residual amount of arsenic in water was below maximum allowed concentrations, while the concentration of antimony, remained above the maximum allowed value. The final phase of purification process was performed using ion exchange resin. After treatment of MMW, they can be used as technical water in the smelting process of secondary raw lead materials

Olovna alkalna šljaka u inovativnom procesu reciklaže sa predtretmanom, stabilizacijom i solidifikacijom

Alkaline lead slag is a waste generated in the pyrometallurgical process of the recycling of materials based on lead with the addition of a sodium(I)-carbonate (Na2CO3) as a flux. The doctoral dissertation includes investigation of a combined process of recycling of lead materials from primary and secondary sources, as well as the possibility of pre-treatment, stabilization and solidification of the industrial sample of lead alkaline slag from the recycling process of spent lead acid batteries. In the first part of the research, the smelting process of lead materials in a short rotary furnace was examined in laboratory conditions. In the process, lead concentrate (primary raw material) and desumporized lead paste (secondary raw material) were used, after their detailed characterization including chemical and granulometric composition of the lead concentrate, as well as the chemical composition of the desumporized lead paste. The smelting process was tested in the function of the batch composition, temperature, rotation and process time in the furnace. The efficacy of the smelting process was estimated based on the achieved degree of extraction of lead from raw materials, physical and chemical properties (chemical composition, basicity, viscosity) and quantities of generated slag. The best result of the extraction efficiency of lead (98.38 %) was obtained in an experiment with combined smelting of lead concentrate (50 %) and desumporized lead paste (50 %). Slag is generated in the amount of 32 % in relation to the weight of the charge, with a content of 3.34% of lead. XRD analysis of the slag showed Na4Ca4 (Si6O18), Fe2SiO4 and FeO as the main phases (OH), less CaFe2O4, whereas FeO was the least present. Due to the use of relatively pure raw material in charge mixture, the amount of As in the generated slag was low (0.003 %). The viscosity of the generated slag was 60 P (kg/(m·s)) at 1100 ° C, which was satisfactory in terms of the good separation of the slag from the metal, and the calculated value of the basicity of 0.85 indicated its slightly acidic character. The second part of the study included the investigation of the pre-treatment process of the industrial sample of alkaline lead slag generated in the recycling process of spent lead-acid batteries. The water leaching of elements (Na, S, As, Fe, Pb) from the slag, in a reactior (discontinuous leaching) and in the innovative device, with a cylindrical-rotating washer-separator (continuous leaching) was examined. The research included the study of the possibility of removing of water soluble components from the slag, the maximum valorization of useful components, and the minimization of waste streams from the process. The starting slag is characterized. Its chemical composition, granulometric composition, mass change and slag granulation with time, solubility in water and treatment according to standard procedures (TCLP, EN 12457-2) are determined. The results of the characterization of alkaline lead slug pointed to its hazardous and specific nature (hygroscopicity, time delamination, solubility in water) and the content of toxic elements that potentially could affect the environment. Leaching degrees of Na, S and As from slag were dominant. The effects of L/S ratio, stirring speed and temperature were analyzed in the function of time. Maximum leaching degrees 95.78 % Na, 75.34 % S and 79.89 % As were determined for L/S = 20, w = 600 min-1, T = 333 K and 120 min. As kinetics was explained by the process of three-dimensional diffusion and activation energy of 15.55 kJ·mol-1. The kinetics of Na and S are explained by the two-degree diffusion model through a cylindrical layer of products, with activation energies of 18.71 kJ·mol-1 and 17.24 kJ·mol-1 respectively. The obtained results of the leaching test were used in the optimization of the patent process of the continuous pre-treatment of alkaline lead slag in the rotating-cylinder washer/separator (T = 313 K, L/S = 10, w = 200 min-1 with the setting of the retention time). In the continuous leaching process of 60 min, the maximum degree of leaching was determined Na 45 %, S 45 % and As 70 % as well as the degree of Na2SO4 utilization from the solution of 10 %, relative to the desulphurization phase of the paste. With pre-treatment of the slag in the discontinuous process, for the conditions of treatment: L/S=20, w =600 min-1, T = 333 K and 120 min, a reduction in mass of about 30% was achieved, and in the continuous process, for the elimination conditions L/S=10, w=200 min-1, T = 313 K, with adjusting retention time, about 20%. The metal-sulfide phase of the slag (fraction + 1mm) was returned to the smelting process in order to obtain useful metals. The phase of finer granulation (- 1mm) was characterized (TCLP test) as a hazardous type of waste, due to the Pb released (pH ~ 3) higher than MDK (5.00 mg·L-1) in strongly acidic conditions and further treated by stabilization/solidification process (S/S)...Olovna alkalna šljaka je otpad koji se generiše u pirometalurškom procesu prerade olovnih sirovina, sa dodatkom topitelja natrijum(I)-karbonata (Na2CO3). U izradi doktorske disertacije ispitivan je kombinovani proces prerade olovnih sirovina iz primarnih i sekundarnih izvora, kao i mogućnost predtretmana, stabilizacije i solidifikacije industrijskog uzorka olovne alkalne šljake iz procesa reciklaže istrošenih olovnih akumulatora. U prvom delu istraživanja analiziran je proces topljenja olovnih sirovina u kratkoj rotacionoj peći, u laboratorijskim uslovima. U procesu su korišćeni olovni koncentrat (primarna sirovina) i desumporizovana olovna pasta (sekundarna sirovina), posle njihove detaljne karakterizacije, ispitivanja hemijskog i granulometrijskog sastava olovnog koncentrata, kao i hemijskog sastava desumporizovane olovne paste. Topljenje je ispitano u funkciji sastava šarže, temperature, rotacije i vremena zadržavanja materijala u peći. Efikasnost procesa topljenja je procenjena na osnovu ostvarenog stepena ekstrakcije olova iz sirovina, fizičko-hemijskih osobina (hemijski sastav, bazicitet, viskozitet) i količine generisane šljake. Najbolji rezultat efikasnosti ekstrakcije olova (98,38 %) je ostvaren u eksperimentu sa kombinovanim topljenjem olovnog koncentrata (50 %) i desumporizovane olovne paste (50 %). Generisana je šljaka u količini od 32 % u odnosu na masu polaznih sirovina, sa sadržajem 3,34 % olova, u kojoj su metodom rentgenske difrakcije (XRD - X-ray diffraction) identifikovane faze Na4Ca4(Si6O18), Fe2SiO4 i FeO(OH), manje količine faze CaFe2O4, i najmanje faze FeO. Zbog korišćenja relativno čistih sirovina u pogledu primesa, količina As u generisanoj šljaci je bila niska (0,003 %). Viskozitet generisane šljake od 60 P (kg/(m·s)), na temperaturi 1100 °C, bio je zadovoljavajući u pogledu dobrog razdvajanja šljake od metala, a izračunata vrednost baziciteta od 0,85 je ukazala na njen blago kiseli karakter. Drugi deo istraživanja obuhvatio je ispitivanje procesa predtretamana industrijskog uzorka olovne alkalne šljake, generisane u procesu reciklaže istrošenih olovnih akumulatora. Ispitano je luženje elemenata (Na, S, As, Fe, Pb) iz šljake u vodi, u reakcionom balonu (diskontinualno ispiranje) i u inovativnom uređaju, cilindričnom-rotirajućem ispirač-odvajaču (kontinualno ispiranje). Istraživanje je obuhvatilo ispitivanje mogućnosti uklanjanja u vodi rastvornih komponenata šljake, maksimalnu valorizaciju korisnih komponenata i minimizaciju otpadnih tokova iz procesa. Polazna šljaka je detaljno karakterisana, određen je hemijski i granulometriski sasatav, promena mase i granulacije šljake sa vremenom, rastvorljivost u vodi i proces luženja elemenata po standardnim procedurama (Toxicity characteristic leaching procedure – TCLP, EN 12457-2). Rezultati su ukazali na opasnu i specifičnu prirodu olovne alkalne šljake, što se ogleda u higroskopnosti, formiranju praškaste forme sa skladištenjem u atmosferi vazduha, rastvorljivosti u vodi i sadržaju toksičnih i migratornih elemenata koji mogu ugroziti životnu sredinu. Proces luženja Na, S i As iz šljake u vodi je bio dominantan. Uticaji odnosa tečno:čvrsto (L/S), brzine mešanja rastvora (w) i temperature (T) na luženje elemenata iz šljake ispitani su u funkciji vremena. Maksimalne vrednosti stepena izluženja Na od 95,78 %, S od 75,34 % i As od 79,89 % su proračunata za L / S = 20, w = 600 min-1, T = 333 K i 120 min izvođenja eksperimenta. Analiza kinetičkih parametara procesa luženja As je ukazala na model tro-dimenzione difuzije, sa energijom aktivacije 15,55 kJ∙mol-1. Luženje Na i S je objašnjeno po modelu dvo-stepene difuzije kroz cilindričan sloj proizvoda, sa energijama aktivacije 18,71 kJ∙mol-1 i 17,24 kJ∙mol-1, redom. Rezultati dobijeni u diskontinualnom procesu ispiranja šljake sa vodom su korišćeni u optimizaciji patentiranog procesa kontinualnog predtretmana olovne alkalne šljake u inovativnom uređaju, cilindričnom-rotirajućem ispirač-odvajaču (T = 313 K, L/S = 10, w = 200 min-1 sa podešavanjem vremena zadržavanja). U procesu kontinualnog ispiranja od 60 min proračunati su maksimalni stepeni izluženja Na 45 %, S 45 % i As 70 %, kao i stepen iskorišćenja Na2SO4 iz rastvora od ispiranja do 10 %, u odnosu na fazu desumporizacije paste. Sa ispiranjem šljake u diskontinulanom procesu (L / S = 20, w = 600 min-1, T = 333 K i 120 min), ostvareno je smanjenje mase od oko 30 %, a u kontinualnom procesu (L/S = 10, w = 200 min-1, T = 313 K, sa podešavanjem vremena zadržavanja), oko 20 %. Krupnija frakcija šljake (+1 mm), bogata metal-sulfidnim komponetama (kamenac), vraćena je u proces topljenja, u cilju valorizacije korisnih metala. Sitnija frakcija šljake (-1 mm), karakterisana je u opasnu vrstu otpada po TCLP testu, zbog koncentracije Pb u kiselim (pH ~3) lužnim rastvorima iznad maksimalno dozvoljene koncentracije (MDK) (5,00 mg·L-1), i dalje korišćena u pocesu stabilizacije i solidifikacije (S/S)..

Alkaline lead in an innovative recycling process with pretreatment, stabilization and solidification

Olovna alkalna šljaka je otpad koji se generiše u pirometalurškom procesu prerade olovnih sirovina, sa dodatkom topitelja natrijum(I)-karbonata (Na2CO3). U izradi doktorske disertacije ispitivan je kombinovani proces prerade olovnih sirovina iz primarnih i sekundarnih izvora, kao i mogućnost predtretmana, stabilizacije i solidifikacije industrijskog uzorka olovne alkalne šljake iz procesa reciklaže istrošenih olovnih akumulatora. U prvom delu istraživanja analiziran je proces topljenja olovnih sirovina u kratkoj rotacionoj peći, u laboratorijskim uslovima. U procesu su korišćeni olovni koncentrat (primarna sirovina) i desumporizovana olovna pasta (sekundarna sirovina), posle njihove detaljne karakterizacije, ispitivanja hemijskog i granulometrijskog sastava olovnog koncentrata, kao i hemijskog sastava desumporizovane olovne paste. Topljenje je ispitano u funkciji sastava šarže, temperature, rotacije i vremena zadržavanja materijala u peći. Efikasnost procesa topljenja je procenjena na osnovu ostvarenog stepena ekstrakcije olova iz sirovina, fizičko-hemijskih osobina (hemijski sastav, bazicitet, viskozitet) i količine generisane šljake. Najbolji rezultat efikasnosti ekstrakcije olova (98,38 %) je ostvaren u eksperimentu sa kombinovanim topljenjem olovnog koncentrata (50 %) i desumporizovane olovne paste (50 %). Generisana je šljaka u količini od 32 % u odnosu na masu polaznih sirovina, sa sadržajem 3,34 % olova, u kojoj su metodom rentgenske difrakcije (XRD - X-ray diffraction) identifikovane faze Na4Ca4(Si6O18), Fe2SiO4 i FeO(OH), manje količine faze CaFe2O4, i najmanje faze FeO. Zbog korišćenja relativno čistih sirovina u pogledu primesa, količina As u generisanoj šljaci je bila niska (0,003 %). Viskozitet generisane šljake od 60 P (kg/(m·s)), na temperaturi 1100 °C, bio je zadovoljavajući u pogledu dobrog razdvajanja šljake od metala, a izračunata vrednost baziciteta od 0,85 je ukazala na njen blago kiseli karakter. Drugi deo istraživanja obuhvatio je ispitivanje procesa predtretamana industrijskog uzorka olovne alkalne šljake, generisane u procesu reciklaže istrošenih olovnih akumulatora. Ispitano je luženje elemenata (Na, S, As, Fe, Pb) iz šljake u vodi, u reakcionom balonu (diskontinualno ispiranje) i u inovativnom uređaju, cilindričnom-rotirajućem ispirač-odvajaču (kontinualno ispiranje). Istraživanje je obuhvatilo ispitivanje mogućnosti uklanjanja u vodi rastvornih komponenata šljake, maksimalnu valorizaciju korisnih komponenata i minimizaciju otpadnih tokova iz procesa. Polazna šljaka je detaljno karakterisana, određen je hemijski i granulometriski sasatav, promena mase i granulacije šljake sa vremenom, rastvorljivost u vodi i proces luženja elemenata po standardnim procedurama (Toxicity characteristic leaching procedure – TCLP, EN 12457-2). Rezultati su ukazali na opasnu i specifičnu prirodu olovne alkalne šljake, što se ogleda u higroskopnosti, formiranju praškaste forme sa skladištenjem u atmosferi vazduha, rastvorljivosti u vodi i sadržaju toksičnih i migratornih elemenata koji mogu ugroziti životnu sredinu. Proces luženja Na, S i As iz šljake u vodi je bio dominantan. Uticaji odnosa tečno:čvrsto (L/S), brzine mešanja rastvora (w) i temperature (T) na luženje elemenata iz šljake ispitani su u funkciji vremena. Maksimalne vrednosti stepena izluženja Na od 95,78 %, S od 75,34 % i As od 79,89 % su proračunata za L / S = 20, w = 600 min-1, T = 333 K i 120 min izvođenja eksperimenta. Analiza kinetičkih parametara procesa luženja As je ukazala na model tro-dimenzione difuzije, sa energijom aktivacije 15,55 kJ∙mol-1. Luženje Na i S je objašnjeno po modelu dvo-stepene difuzije kroz cilindričan sloj proizvoda, sa energijama aktivacije 18,71 kJ∙mol-1 i 17,24 kJ∙mol-1, redom. Rezultati dobijeni u diskontinualnom procesu ispiranja šljake sa vodom su korišćeni u optimizaciji patentiranog procesa kontinualnog predtretmana olovne alkalne šljake u inovativnom uređaju, cilindričnom-rotirajućem ispirač-odvajaču (T = 313 K, L/S = 10, w = 200 min-1 sa podešavanjem vremena zadržavanja). U procesu kontinualnog ispiranja od 60 min proračunati su maksimalni stepeni izluženja Na 45 %, S 45 % i As 70 %, kao i stepen iskorišćenja Na2SO4 iz rastvora od ispiranja do 10 %, u odnosu na fazu desumporizacije paste. Sa ispiranjem šljake u diskontinulanom procesu (L / S = 20, w = 600 min-1, T = 333 K i 120 min), ostvareno je smanjenje mase od oko 30 %, a u kontinualnom procesu (L/S = 10, w = 200 min-1, T = 313 K, sa podešavanjem vremena zadržavanja), oko 20 %. Krupnija frakcija šljake (+1 mm), bogata metal-sulfidnim komponetama (kamenac), vraćena je u proces topljenja, u cilju valorizacije korisnih metala. Sitnija frakcija šljake (-1 mm), karakterisana je u opasnu vrstu otpada po TCLP testu, zbog koncentracije Pb u kiselim (pH ~3) lužnim rastvorima iznad maksimalno dozvoljene koncentracije (MDK) (5,00 mg·L-1), i dalje korišćena u pocesu stabilizacije i solidifikacije (S/S)...Alkaline lead slag is a waste generated in the pyrometallurgical process of the recycling of materials based on lead with the addition of a sodium(I)-carbonate (Na2CO3) as a flux. The doctoral dissertation includes investigation of a combined process of recycling of lead materials from primary and secondary sources, as well as the possibility of pre-treatment, stabilization and solidification of the industrial sample of lead alkaline slag from the recycling process of spent lead acid batteries. In the first part of the research, the smelting process of lead materials in a short rotary furnace was examined in laboratory conditions. In the process, lead concentrate (primary raw material) and desumporized lead paste (secondary raw material) were used, after their detailed characterization including chemical and granulometric composition of the lead concentrate, as well as the chemical composition of the desumporized lead paste. The smelting process was tested in the function of the batch composition, temperature, rotation and process time in the furnace. The efficacy of the smelting process was estimated based on the achieved degree of extraction of lead from raw materials, physical and chemical properties (chemical composition, basicity, viscosity) and quantities of generated slag. The best result of the extraction efficiency of lead (98.38 %) was obtained in an experiment with combined smelting of lead concentrate (50 %) and desumporized lead paste (50 %). Slag is generated in the amount of 32 % in relation to the weight of the charge, with a content of 3.34% of lead. XRD analysis of the slag showed Na4Ca4 (Si6O18), Fe2SiO4 and FeO as the main phases (OH), less CaFe2O4, whereas FeO was the least present. Due to the use of relatively pure raw material in charge mixture, the amount of As in the generated slag was low (0.003 %). The viscosity of the generated slag was 60 P (kg/(m·s)) at 1100 ° C, which was satisfactory in terms of the good separation of the slag from the metal, and the calculated value of the basicity of 0.85 indicated its slightly acidic character. The second part of the study included the investigation of the pre-treatment process of the industrial sample of alkaline lead slag generated in the recycling process of spent lead-acid batteries. The water leaching of elements (Na, S, As, Fe, Pb) from the slag, in a reactior (discontinuous leaching) and in the innovative device, with a cylindrical-rotating washer-separator (continuous leaching) was examined. The research included the study of the possibility of removing of water soluble components from the slag, the maximum valorization of useful components, and the minimization of waste streams from the process. The starting slag is characterized. Its chemical composition, granulometric composition, mass change and slag granulation with time, solubility in water and treatment according to standard procedures (TCLP, EN 12457-2) are determined. The results of the characterization of alkaline lead slug pointed to its hazardous and specific nature (hygroscopicity, time delamination, solubility in water) and the content of toxic elements that potentially could affect the environment. Leaching degrees of Na, S and As from slag were dominant. The effects of L/S ratio, stirring speed and temperature were analyzed in the function of time. Maximum leaching degrees 95.78 % Na, 75.34 % S and 79.89 % As were determined for L/S = 20, w = 600 min-1, T = 333 K and 120 min. As kinetics was explained by the process of three-dimensional diffusion and activation energy of 15.55 kJ·mol-1. The kinetics of Na and S are explained by the two-degree diffusion model through a cylindrical layer of products, with activation energies of 18.71 kJ·mol-1 and 17.24 kJ·mol-1 respectively. The obtained results of the leaching test were used in the optimization of the patent process of the continuous pre-treatment of alkaline lead slag in the rotating-cylinder washer/separator (T = 313 K, L/S = 10, w = 200 min-1 with the setting of the retention time). In the continuous leaching process of 60 min, the maximum degree of leaching was determined Na 45 %, S 45 % and As 70 % as well as the degree of Na2SO4 utilization from the solution of 10 %, relative to the desulphurization phase of the paste. With pre-treatment of the slag in the discontinuous process, for the conditions of treatment: L/S=20, w =600 min-1, T = 333 K and 120 min, a reduction in mass of about 30% was achieved, and in the continuous process, for the elimination conditions L/S=10, w=200 min-1, T = 313 K, with adjusting retention time, about 20%. The metal-sulfide phase of the slag (fraction + 1mm) was returned to the smelting process in order to obtain useful metals. The phase of finer granulation (- 1mm) was characterized (TCLP test) as a hazardous type of waste, due to the Pb released (pH ~ 3) higher than MDK (5.00 mg·L-1) in strongly acidic conditions and further treated by stabilization/solidification process (S/S)..

Alkaline lead in an innovative recycling process with pretreatment, stabilization and solidification

Olovna alkalna šljaka je otpad koji se generiše u pirometalurškom procesu prerade olovnih sirovina, sa dodatkom topitelja natrijum(I)-karbonata (Na2CO3). U izradi doktorske disertacije ispitivan je kombinovani proces prerade olovnih sirovina iz primarnih i sekundarnih izvora, kao i mogućnost predtretmana, stabilizacije i solidifikacije industrijskog uzorka olovne alkalne šljake iz procesa reciklaže istrošenih olovnih akumulatora. U prvom delu istraživanja analiziran je proces topljenja olovnih sirovina u kratkoj rotacionoj peći, u laboratorijskim uslovima. U procesu su korišćeni olovni koncentrat (primarna sirovina) i desumporizovana olovna pasta (sekundarna sirovina), posle njihove detaljne karakterizacije, ispitivanja hemijskog i granulometrijskog sastava olovnog koncentrata, kao i hemijskog sastava desumporizovane olovne paste. Topljenje je ispitano u funkciji sastava šarže, temperature, rotacije i vremena zadržavanja materijala u peći. Efikasnost procesa topljenja je procenjena na osnovu ostvarenog stepena ekstrakcije olova iz sirovina, fizičko-hemijskih osobina (hemijski sastav, bazicitet, viskozitet) i količine generisane šljake. Najbolji rezultat efikasnosti ekstrakcije olova (98,38 %) je ostvaren u eksperimentu sa kombinovanim topljenjem olovnog koncentrata (50 %) i desumporizovane olovne paste (50 %). Generisana je šljaka u količini od 32 % u odnosu na masu polaznih sirovina, sa sadržajem 3,34 % olova, u kojoj su metodom rentgenske difrakcije (XRD - X-ray diffraction) identifikovane faze Na4Ca4(Si6O18), Fe2SiO4 i FeO(OH), manje količine faze CaFe2O4, i najmanje faze FeO. Zbog korišćenja relativno čistih sirovina u pogledu primesa, količina As u generisanoj šljaci je bila niska (0,003 %). Viskozitet generisane šljake od 60 P (kg/(m·s)), na temperaturi 1100 °C, bio je zadovoljavajući u pogledu dobrog razdvajanja šljake od metala, a izračunata vrednost baziciteta od 0,85 je ukazala na njen blago kiseli karakter. Drugi deo istraživanja obuhvatio je ispitivanje procesa predtretamana industrijskog uzorka olovne alkalne šljake, generisane u procesu reciklaže istrošenih olovnih akumulatora. Ispitano je luženje elemenata (Na, S, As, Fe, Pb) iz šljake u vodi, u reakcionom balonu (diskontinualno ispiranje) i u inovativnom uređaju, cilindričnom-rotirajućem ispirač-odvajaču (kontinualno ispiranje). Istraživanje je obuhvatilo ispitivanje mogućnosti uklanjanja u vodi rastvornih komponenata šljake, maksimalnu valorizaciju korisnih komponenata i minimizaciju otpadnih tokova iz procesa. Polazna šljaka je detaljno karakterisana, određen je hemijski i granulometriski sasatav, promena mase i granulacije šljake sa vremenom, rastvorljivost u vodi i proces luženja elemenata po standardnim procedurama (Toxicity characteristic leaching procedure – TCLP, EN 12457-2). Rezultati su ukazali na opasnu i specifičnu prirodu olovne alkalne šljake, što se ogleda u higroskopnosti, formiranju praškaste forme sa skladištenjem u atmosferi vazduha, rastvorljivosti u vodi i sadržaju toksičnih i migratornih elemenata koji mogu ugroziti životnu sredinu. Proces luženja Na, S i As iz šljake u vodi je bio dominantan. Uticaji odnosa tečno:čvrsto (L/S), brzine mešanja rastvora (w) i temperature (T) na luženje elemenata iz šljake ispitani su u funkciji vremena. Maksimalne vrednosti stepena izluženja Na od 95,78 %, S od 75,34 % i As od 79,89 % su proračunata za L / S = 20, w = 600 min-1, T = 333 K i 120 min izvođenja eksperimenta. Analiza kinetičkih parametara procesa luženja As je ukazala na model tro-dimenzione difuzije, sa energijom aktivacije 15,55 kJ∙mol-1. Luženje Na i S je objašnjeno po modelu dvo-stepene difuzije kroz cilindričan sloj proizvoda, sa energijama aktivacije 18,71 kJ∙mol-1 i 17,24 kJ∙mol-1, redom. Rezultati dobijeni u diskontinualnom procesu ispiranja šljake sa vodom su korišćeni u optimizaciji patentiranog procesa kontinualnog predtretmana olovne alkalne šljake u inovativnom uređaju, cilindričnom-rotirajućem ispirač-odvajaču (T = 313 K, L/S = 10, w = 200 min-1 sa podešavanjem vremena zadržavanja). U procesu kontinualnog ispiranja od 60 min proračunati su maksimalni stepeni izluženja Na 45 %, S 45 % i As 70 %, kao i stepen iskorišćenja Na2SO4 iz rastvora od ispiranja do 10 %, u odnosu na fazu desumporizacije paste. Sa ispiranjem šljake u diskontinulanom procesu (L / S = 20, w = 600 min-1, T = 333 K i 120 min), ostvareno je smanjenje mase od oko 30 %, a u kontinualnom procesu (L/S = 10, w = 200 min-1, T = 313 K, sa podešavanjem vremena zadržavanja), oko 20 %. Krupnija frakcija šljake (+1 mm), bogata metal-sulfidnim komponetama (kamenac), vraćena je u proces topljenja, u cilju valorizacije korisnih metala. Sitnija frakcija šljake (-1 mm), karakterisana je u opasnu vrstu otpada po TCLP testu, zbog koncentracije Pb u kiselim (pH ~3) lužnim rastvorima iznad maksimalno dozvoljene koncentracije (MDK) (5,00 mg·L-1), i dalje korišćena u pocesu stabilizacije i solidifikacije (S/S)...Alkaline lead slag is a waste generated in the pyrometallurgical process of the recycling of materials based on lead with the addition of a sodium(I)-carbonate (Na2CO3) as a flux. The doctoral dissertation includes investigation of a combined process of recycling of lead materials from primary and secondary sources, as well as the possibility of pre-treatment, stabilization and solidification of the industrial sample of lead alkaline slag from the recycling process of spent lead acid batteries. In the first part of the research, the smelting process of lead materials in a short rotary furnace was examined in laboratory conditions. In the process, lead concentrate (primary raw material) and desumporized lead paste (secondary raw material) were used, after their detailed characterization including chemical and granulometric composition of the lead concentrate, as well as the chemical composition of the desumporized lead paste. The smelting process was tested in the function of the batch composition, temperature, rotation and process time in the furnace. The efficacy of the smelting process was estimated based on the achieved degree of extraction of lead from raw materials, physical and chemical properties (chemical composition, basicity, viscosity) and quantities of generated slag. The best result of the extraction efficiency of lead (98.38 %) was obtained in an experiment with combined smelting of lead concentrate (50 %) and desumporized lead paste (50 %). Slag is generated in the amount of 32 % in relation to the weight of the charge, with a content of 3.34% of lead. XRD analysis of the slag showed Na4Ca4 (Si6O18), Fe2SiO4 and FeO as the main phases (OH), less CaFe2O4, whereas FeO was the least present. Due to the use of relatively pure raw material in charge mixture, the amount of As in the generated slag was low (0.003 %). The viscosity of the generated slag was 60 P (kg/(m·s)) at 1100 ° C, which was satisfactory in terms of the good separation of the slag from the metal, and the calculated value of the basicity of 0.85 indicated its slightly acidic character. The second part of the study included the investigation of the pre-treatment process of the industrial sample of alkaline lead slag generated in the recycling process of spent lead-acid batteries. The water leaching of elements (Na, S, As, Fe, Pb) from the slag, in a reactior (discontinuous leaching) and in the innovative device, with a cylindrical-rotating washer-separator (continuous leaching) was examined. The research included the study of the possibility of removing of water soluble components from the slag, the maximum valorization of useful components, and the minimization of waste streams from the process. The starting slag is characterized. Its chemical composition, granulometric composition, mass change and slag granulation with time, solubility in water and treatment according to standard procedures (TCLP, EN 12457-2) are determined. The results of the characterization of alkaline lead slug pointed to its hazardous and specific nature (hygroscopicity, time delamination, solubility in water) and the content of toxic elements that potentially could affect the environment. Leaching degrees of Na, S and As from slag were dominant. The effects of L/S ratio, stirring speed and temperature were analyzed in the function of time. Maximum leaching degrees 95.78 % Na, 75.34 % S and 79.89 % As were determined for L/S = 20, w = 600 min-1, T = 333 K and 120 min. As kinetics was explained by the process of three-dimensional diffusion and activation energy of 15.55 kJ·mol-1. The kinetics of Na and S are explained by the two-degree diffusion model through a cylindrical layer of products, with activation energies of 18.71 kJ·mol-1 and 17.24 kJ·mol-1 respectively. The obtained results of the leaching test were used in the optimization of the patent process of the continuous pre-treatment of alkaline lead slag in the rotating-cylinder washer/separator (T = 313 K, L/S = 10, w = 200 min-1 with the setting of the retention time). In the continuous leaching process of 60 min, the maximum degree of leaching was determined Na 45 %, S 45 % and As 70 % as well as the degree of Na2SO4 utilization from the solution of 10 %, relative to the desulphurization phase of the paste. With pre-treatment of the slag in the discontinuous process, for the conditions of treatment: L/S=20, w =600 min-1, T = 333 K and 120 min, a reduction in mass of about 30% was achieved, and in the continuous process, for the elimination conditions L/S=10, w=200 min-1, T = 313 K, with adjusting retention time, about 20%. The metal-sulfide phase of the slag (fraction + 1mm) was returned to the smelting process in order to obtain useful metals. The phase of finer granulation (- 1mm) was characterized (TCLP test) as a hazardous type of waste, due to the Pb released (pH ~ 3) higher than MDK (5.00 mg·L-1) in strongly acidic conditions and further treated by stabilization/solidification process (S/S)..

The process of interactive treatment of overburden and wastewater from a copper smelter for recovery of copper

Pronalazak jeste postupak interaktivnog tretmana dve vrste otpada koji nastaju tokom primarne proizvodnje bakra u cilju dobijanja bakra. Prvi je oksidna raskrivka nastala iskopavanjem sulfidne rude bakra, koja sadrži alumino-silikatne minerale (70-80%), karbonate alkalnih i zemnoalkalnih metala (10-20%), gvožđe (5-10%) i bakar (0,10-0,20%). Druga vrsta otpada je otpadna voda iz topionice bakra sa visokim sadržajem kiseline (pH<0,90), rastvorenog bakra (≥0,50 g/l) i procesnih nečistoća. Interaktivni tretman podrazumeva mešanje oksidne raskrivke i kisele otpadne vode u hidrometalurškom reaktoru pri čemu se interaktivni efekat ogleda u istovremenim procesima neutralizacije kiseline i luženja bakra. Tretirana otpadna voda (pH≥0,90 i koncentracija Cu ≥1,0 g/dm3), dobijena interaktivnim tretmanom, je pogodna za dobijanje bakra kao katodnog bakra procesom solvent ekstrakcije/elektrovininga. Interaktivnim tretmanom otpada se smanjuje njihov štetan uticaj na životnu sredinu, smanjuje količina odloženog otpada, smanjuje gubitak bakra kroz otpadne tokove i pri tom dobija rastvor pogodan za dobijanje bakra.Broj prijave П-2023/088