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Electric arc furnace dust (EAFD) which is considered hazardous waste, contains significant amounts of Zinc (Zn), iron (Fe), and some dangerous elements. Zn exists in the dust as Zinc Oxide (ZnO) and Zinc Ferrite (ZnFe2O3) which is difficult to be leached with traditional methods. The main objective of the suggested process is to recover Zn from EAFD by using a hybrid pyro/hydrometallurgical method. This method includes mixing cement dust and EAFD and heating the mixture in a pyrometallurgical treatment step to convert ZnFe2O3 to ZnO. This step is followed by leaching the treated dust with sodium hydroxide (NaOH) solution using different Solid/Liquid (S/L) ratios through different time intervals in a hydrometallurgical treatment step. Finally, Zn-metal can be recovered from the leached solution in an electrochemical step (electro-winning). About 82 % of the Zn originally presented in the EAFD sample was successfully extracted by using a treatment mixture of 2:1 cement dust: EAFD at 1000 °C for 2 hrs., then leaching with 2M NaOH solution with an S/L ratio of 1/20 for 6 hrs. at a stirring rate of 250 rpm.

nanoparticles are catching more attention due to their implementation as a filling material in a variety of fields. Nowadays, calcium carbonate nanoparticles have a large number of industrial applications replacing more expensive binders. Global warming and climate change, which are mainly caused by the increased concentration of carbon dioxide gas (CO2), turned to be a significant problem for our society. This research aims to develop an economic mineral carbonation process for the manufacture of nanoprecipitated calcium carbonate (NPCC), which can be considered also as an efficient way for the sequestration of CO2. The proposed research was divided into two stages, during the first stage a pure calcium chloride solution was carbonated, and the effect of different parameters (CO2 flow rate, ammonia amount, presence of additives, stirring rate, and ultrasonic waves) on the yield and the particle size of the produced particles was discussed. Then a synthetic Solvay wastewater sample was prepared and carbonated to study the effect of the presence of impurities on the particle size. The experimental results showed that increasing the amount of ammonia or the gas flow rate can affect the yield of the product while, increasing the stirring rate, the ammonia amount, or a suitable additive like glycerol have the effect to decrease the particle size. In the second stage, a process for ammonia recovery was modeled using Aspen Plus software v8.8 in order to make our process more economic.

Biodiesel is considered a renewable, green fuel as it is derived from renewable living resources like animal fats or vegetable oils. This research is utilized to investigate the possibility of using Solvay wastewater as a source of biodiesel catalyst, which is CaO. CaCl2 from Solvay wastewater reacts with CO2 to produce CaCO3. CaCO3 is then heated to produce pure CaO. Waste cooking oil, wastewater, and CO2, which are considered dangerous materials to the environment, are used to produce valuable products. This research has environmental and economic benefit benefits of using waste materials as a replacement for raw materials. The selected experimental parameters for the CaCO3 production step are stirring rate (500–1300) rpm, CO2 gas flow rate (900–2000) mL/min, amount of ammonia (15–35) mL, and glycerol volume (0–25) mL. The selected experimental parameters for the biodiesel production step are reaction time (2–6) h, methanol to oil ratio (9–15), catalyst loading (1–5) %, and reaction temperature (50–70) °C. The impact of reaction parameters on reaction responses was assessed using the response surface methodology technique. A formula that represents the reaction response as a function of all the independent factors has been created. The optimization of the process is done in two steps: the first one is for the CaCO3 process while the second one is biodiesel production optimization. The first optimization was done to get the CaCO3 with minimum particle size and yield. The second optimization was done to get the maximum amount of biodiesel using minimum energy and low reaction conditions. Process optimization resulted in another economic benefit for this research. The resulted biodiesel yield equals 95.8% biodiesel yield at 2 h reaction time, 15:1 molar ratio of methanol to oil, 56 °C reaction temperature, and 1% catalyst loading.