Thermal characterization of ferronickel slag waste has been studied using TG / DTA, XRD, and SEM-EDX. The characterization of the initial samples of ferronickel slag was carried out TG / DTA to 1200°C. The result obtained is at a temperature of 800°C, there is an increasing mass and up to 4.68% at a temperature of 1200°C. At temperature of 807.4°C to 845.8°C, an exothermic reaction occurs. The increasing mass is due to the ferronickel slag which is originally in the form of metal, and then it was roasted to undergo an oxidation reaction so that the metal that has been formed, it returned into oxides. So that the weight of the sample mass increase. Samples of ferronickel slag added with sodium carbonate were also analyzed using TG / DTA. The results obtained are 2 endothermic peaks at temperatures of 90.6°C and 858.9°C with a total mass reduction of 49.3%. At a temperature of 90.6°C, there is a heavy loss caused by 2.38% loss of surface water. The XRD result of ferronickel slag is composed of enstatite (MgSiO3), forsterite (Mg2SiO4), fayalite (Fe2SiO4), and quartz (SiO2) structures. From the XRD analysis, the composition of silica oxide associates with magnesium and iron in the form of enstatite, forsterite, and fayalites is a very dominant composition. The roasting process of a mixture of ferronickel slag with sodium carbonate was carried out by heating at a temperature of 800-1000°C for 1 hour, and the sample result of roasting were analyzed using XRD. The result of roasting shows that the roasting process takes place more perfectly at higher temperature; it is indicated by the increasing phase intensity of SiO2 and the formation of sodium silicate (Na2SiO3). The result of SEM shows that the higher the temperature, the distribution of Na, Si, and O elements tend to cluster in the same place or spot, while the elements of Mg, Si, and O are less bonded.

Nickel industry is one of the most strategic industries because its widely used. Nickel slag as a by-product of nickel processing presents the potential for improving process efficiency. In this study aim to determine the effect of the addition of sodium sulfate additives and also the temperature in the reduction process of nickel slag. The research was preceded by preparation of nickel slag samples with crushing and sieving up to 200 mesh. The nickel slag is then reduced at 800°C, 900°C and 1000°C temperature without adding sodium sulfate and by adding sodium sulfate with 1 hour holding time. Furthermore, the results of the reduction is done XRD and AAS testing to see changes in the content of elements and compounds in nickel slag that has been tested. The results of the study explain that the content of the dominant impurities which is in the form of SiO2 decreases as the temperature of the reduction and iron from Fe-rich Forsterite compounds will be liberated and will bind to sulfur derived from sodium sulfate to form troilite (FeS). This results in an increasing content of valuable minerals present in the nickel slag.

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Nickel slag is one of the output from nickel ore smelting. In Indonesia itself, further utilization of valuable elements in it is needed to be processed. Nickel slag also has Fayalite (Fe2SiO4) content where nickel and copper are spread evenly on the iron matrix silica which then complicate the process of increasing nickel and copper content. The addition of Sodium Carbonate (Naoh) is used as a silica binder and as an alternative way to increase nickel and copper content. In this research, pyrometallurgy is done by coal as a reductor in 800°C, 900°C and 1000°C operating temperature and ratio between nickel slag and additive equal to 1:1, 1:2, and 2:1. Based on this study, it is obtained that with the increasing of temperature without additive, there is still found the presence of silica in a form of Fe-rich Forsterite (FeMgSiO4) and Olivine (NiMgSiO4). Whereas with the presence of additive in slag nickel pyrometallurgy with a different temperature and ratio, it is seen that there is a phase formation of Sdoium Magnesiosilicate (Na2MgSiO4), Magnesium Oxide (MgO) and Wustite (FeO) which proved the binding of silica and has liberate iron that helps the process of increasing nickel and copper content.

Проведено дослiдження з вилучення магнiю з феронiкелевого шлаку, обробленого зворотним вилуговуванням розчинами гiдроксиду натрiю (NaOH). Феронiкелевий шлак в основному складається з силiкату магнiю i силiкату залiза. Першим етапом дослiдження була пiдготовка феронiкелевого шлаку до подрiбнення за допомогою кульового млина до розмiру-200 меш. По-друге, прожарювання феронiкелевих шлакiв для видалення кристалiчної води i збiльшення пористостi для полегшення процесу вилуговування. Наступним кроком було зворотне вилуговування з використанням гiдроксиду натрiю (NaOH) для розчинення кремнезему. При розчиненнi кремнезему очiкувалося збiльшення вмiсту в залишку таких елементiв, як магнiй i залiзо. Змiнними в даному дослiдженнi з вилуговування феронiкелевого шлаку були час вилуговування, концентрацiя розчинника i температура вилуговування. Зворотне вилуговування феронiкелевого шлаку проводили зi змiною часу вiд 15 до 240 хвилин, температурою 30 °С, 70 °С i 100 °С, концентрацiями NaOH 9 М, 10 М i 11 М. Для вивчення вихiдних характеристик феронiкелевого шлаку i результатiв процесу вилуговування використовували рентгеноструктурний аналiз, рентгенофлуоресцентний аналiз i мас-спектрометрiю з iндуктивно-зв'язаною плазмою. Результати визначення характеристик зразкiв феронiкелевого шлаку методом рентгеноструктурного аналiзу показують, що в складi домiнуючих з'єднань присутнi форстерит (Mg 2 SiO 4), енстатiт (MgSiO 3) i фаялiт (Fe 2 SiO 4). Крiм того, результати також пiдтверджуються рентгенофлуоресцентним аналiзом i растровою електронною мiкроскопiєю. Кiлькiсний РФА аналiз показує, що феронiкелевий шлак мiстить 45,69 % SiO 2 , 29,32 % MgO i 16,5 % Fe 2 O 3. Результати растрової електронної мiкроскопiї показують, що Mg, Si, Fe i O зв'язуються разом, що вказує на присутнiсть силiкату магнiю i силiкату залiза. Найбiльший вiдсоток вилучення магнiю становить 73,10 % в умовах експериментальної температури 100 °С протягом 240 хвилин, концентрацiї розчинника 10 М i швидкостi перемiшування 300 об/хв. Збiльшення вiдсотка вилучення магнiю обумовлено розчиненням кремнезему в процесi вилуговування. Розчинення кремнезему пiдтверджується наявнiстю гiдроксиду магнiю i гiдроксиду залiза (II) в залишку, що показано рентгеноструктурним аналiзом. Це призвело до значного збiльшення вмiсту MgO в залишку до 42,8 %, як показав рентгенофлуоресцентний аналiз. Крiм того, растрова електронна мiкроскопiя показує, що Mg i O зв'язуються разом, що вказує на присутнiсть MgO. Також можна визначити, що MgO є домiнуючим Ключовi слова: феронiкель, шлак, форстерит, магнiй, кремнезем, вилуговування, зворотне вилуговування, гiдроксид натрiю, фiльтрат, залишок ,% вилучення

Graphene and silica are two materials that have wide uses and applications because of their unique properties. Graphene/silica hybrid composite, which is a combination of the two, has the good properties of a combination of graphene and silica while reducing the detrimental properties of both, so that it has promising future prospects in various fields. It is very important to design a synthesis method for graphene/silica composite hybrid materials to adapt to its practical application. In this review, the synthesis strategies of graphene, silica, and hybrid graphene/silica composites such as hydrothermal, sol-gel, hydrolysis, and encapsulation methods along with their results are studied. The application of this composite is also discussed, which includes applications such as adsorbents, energy storage, biomedical fields, and catalysts. Furthermore, future research challenges and futures need to be developed so that hybrid graphene/silica composites can be obtained with promising new application prospects.

Nickel slag is one of the results of the nickel ore smelting process which is still a waste and has not been used optimally. Considering the amount of nickel slag waste in Indonesia, the effort to utilize it into a more valuable product becomes very important. Therefore, in order to extract the precious metal content in nickel slag, this study aims to analyze the effect of adding sodium carbonate in the reduction process of nickel slag. In this study, the reduction process is carried out using coal as a reducing agent, where the variation of the reduction temperature is 800, 900, and 1000°C; while the variation of the ratio between nickel slag and additives is 1:1, 1:2, and 2:1. The XRD analysis results show that the temperature rise up to 1000 °C and the addition of sodium carbonate will increase the amount of sodium magnesiosilicate up to 29.4% and also hematite up to 25.1%. The same thing happened in samples with a ratio of 1:1 and 1:2 where the amount of sodium magnesiosilicate increased from 29.4% to 30.0% and hematite from 25.1% to 28.8%.