abolfazl danesh

The industrial data gathered from the control room of the Phase 2 plant and the initial processing of the data were utilized in the SIMKA software which determined 13 parameters affecting the consumption of media in semi-autogenous grinding. Based on the results, it was found that in multivariate analysis methods, the amount of filling increases with increasing input tonnage. The filling is directly related to input tonnage and power and is associated with ball charge, which increases with increasing ball charge. By increasing the level of the grinding load, the amount of mineral-mineral collision decreases, and the ball-ball collision increases, causing the consumption of grinding media. The simulation results clearly showed that in the face of the problems created, instead of changing the size of the balls and enlarging them, which leads to the breaking of liners and nets, it is recommended to increase the percentage of ball accumulation to its maximum (%15), particularly in hard feed. This study clearly shows that the effect of particle size is even greater than the effect of particle hardness.

Loss of copper minerals to tailings of the rougher and scavenger circuits is one of the challenges in copper concentration plants, which reduces the efficiency of the circuit. The goal of this research is to utilize mineralogy-based techniques to identify the cause of the loss of copper minerals to tailings of the scavenger circuit. Process mineralogy studies have been performed on the scavenger of the flotation circuit - the Sungun copper concentration plant (located in northwestern of Iran). First, the feed, final concentrate, and tailing, as well as the concentrate and tailing flows of each of the scavenger circuit cells were sampled at different time intervals. Then, chemical composition analysis, laser particle size distribution analysis, and optical microscopy studies were performed on them. According to the results, the presence and changes in the abundance of copper oxide minerals, which make up about 45% of copper minerals, is one of the main reasons for the copper loss to tailings. Also, fine-grained particles of copper sulfide minerals (d80~45 µm), and the interlocking of copper sulfide minerals, especially chalcopyrite, with pyrite and gangue minerals (silicate), are among the most important causes of increased copper grade in the scavenger circuit tailings. In addition, the malfunction of the scavenger circuit cells due to the simultaneous presence of sulfide and oxide minerals and their fineness is another cause of the lost to tailings.

Loss of copper minerals in the tailings of the rougher and scavenger circuits poses a significant challenge in copper processing plants, diminishing the circuit's efficiency. Part I of this paper identified the causes of copper mineral loss in the scavenger circuit tailings of the Sungun copper concentration plant, situated in northwestern Iran. Changes in feed composition, particularly the ratio of copper oxide to sulfide minerals, along with alterations in the mineralogical properties of the input feed to the scavenger circuit, emerged as pivotal factors contributing to the loss of copper minerals into the tailings. In line with these findings, the objective of the present paper (part II) is to optimize the scavenger circuit by proposing a solution to mitigate the loss of copper minerals to the tailings. Samples were collected from the feed, concentrate, and final tailings, as well as from each cell of the scavenger circuit, followed by comminution and flotation tests on each sample. The results indicate that redirecting the scavenger circuit tailings to the input of the rougher cells, owing to their higher copper grade compared to the tailings of the rougher circuit, can enhance the circuit's recovery by more than 4%. Additionally, employing a combination of sulfide and oxide collectors, along with sulfidation to float the copper oxide minerals in the scavenger circuit, resulted in an overall recovery increase exceeding 11%. Furthermore, adjusting the size of the air bubbles to capture fine copper mineral particles from the scavenger circuit cells proved to be an effective strategy for boosting recovery. Moreover, modifying the grinding circuit to liberate the minerals present in the scavenger circuit feed, predominantly the concentrate of the scavenger circuit itself, led to a recovery increase of approximately 5%. Considering the mineralogical characteristics of the scavenger circuit feed, derived from the tailings of the cleaner cells, implementing changes in the operating conditions of the cleaner circuit—such as employing hybrid bubbles (Nano and coarse bubbles) and utilizing sulfide and oxide collectors—significantly impacted the recovery of fine copper mineral particles and copper oxide minerals to the cleaner concentrate, thereby enhancing the scavenger circuit's performance.

Aflatoxin B1 is a type of mycotoxin produced by Aspergillus fungi during food production and storage. Aflatoxins have many toxic effects on the body that cause mutagens, teratogens and have high carcinogenic properties that cause cancer in the liver and other organs. Although conventional device methods for measuring aflatoxin B1 in food are sensitive and accurate, they have disadvantages such as high diagnostic time, high cost, the need for a trained user, and the creation of false positive results. Therefore, the development of new measuring methods has been prioritized by researchers. Among these measurement methods is the use of biosensors, which are fast, simple and more affordable and are used in the food industry today. In this work, a colorimetric optical aptasensor using gold nanoparticles with appropriate sensitivity and high selectivity was used to detect aflatoxin B1 in serum and buffer. For this purpose, gold nanoparticles were synthesized by reducing HAuCl4 by sodium citrate (with a size of 14.40 nm and a zeta potential of -27.5). In this method, the protective effect of DNA sequence on the surface of gold nanoparticles has been used in the presence or absence of aflatoxin with the intervention of salt and the characteristic of visual color change. The detection limit of this method was estimated to be 50 ng/L and its linear range was 200-28000 ng/L. As a result, the designed aptasensor can be used for quick identification and screening of this toxin in contaminated food.

Contamination of heavy metals in food, especially drinking water and groundwater, has become a serious problem for human health. These metals are mainly the constituent elements of nature widely distributed in the earth's crust, but significant amounts of them are also found in everyday goods. These elements are usually found in combinations with oxygen, chlorine, sulfur, and other anions that generally contain inorganic and organic compounds. Lead is one of the heavy metals with high toxicity that poses serious risks to the environment and humans. Recent advances in nucleic acid research have led to the identification of oligonucleotide sequences that bind with high affinity specifically to target molecules, including proteins. Such single-stranded sequences are called "aptamer" nucleic acids. Aptamers are synthetic single-stranded DNA or RNA sequences of 30 to 100 nucleotides, and their secondary and tertiary structures are folded to make them highly specific for binding to targets. The binding of aptamers to different targets, from a single cell to large chemical and biological molecules, is done with high affinity. This aptamer feature is used to detect lead. In this review article, the designed optical aptasensors for the detection of lead will be reviewed.

In this study, the feasibility of improving the flotation circuit performance of a phase 1 of Sungun copper plant was investigated. For this purpose, circuit performance was first monitored ., It was found that in the rougher stage the some copper exists in fractions greater than 106 and smaller than 38 microns was lost. Final concentrate analysis taken on different days showed that the copper grade decreased due to the iron content increasing. Mineralogical studies also confirmed the maximum presence of pyrite in the final concentrate. Field surveys of the flotation circuit showed that there are many technical problem in the circuit that affect on the flotation process. These drawbacks including the presence of thick tubes at the surface of the re-cleaner cell, the lack of a standard pattern of wash water distribution and jet spraying. Measurement of pH in different points of the circuit showed a decrease of pH below 11 and so hydrophobicity of pyrite caused. Measurement of operating variables in the circuit showed that the wash water rate and gas rate used in the circuit were higher and lower than the values suggested by the researchers and the designer, respectively. Due to the deficiencies identified in the performance evaluation phase, laboratory tests were designed and performed in two stages using mechanical flotation cell and column flotation cell. Adjusting the gas rate and the wash water rate at the laboratory scale at the intervals suggested by the researchers resulted in the increase in 3% grade and 10% recovery.