Magnesium Contamination Research Articles

Investigation of serpentine entrainment reduction in pentlandite flotation using eco-friendly sodium alginate in suspension dispersion systems

Magnesium silicates pose severe environmental issues in hydrometallurgical processes. Copper-nickel sulfide ores are the primary source for nickel production, but their increasingly complex properties make separation difficult, causing slimy magnesium silicate minerals to be entrained into the concentrate with the foam, leading to magnesium contamination. Studies have found that sodium alginate (SA), as an environmentally friendly polymer reagent, can effectively inhibit serpentine. This work investigates the effect of SA on the flotation behavior of pentlandite and serpentine in a sodium hexametaphosphate (SHMP) system. Sedimentation tests show that only a low dosage of SA can effectively settle serpentine, while excessive SA disperses serpentine. Flotation tests indicate that SA can further increase the difference in recovery rates between pentlandite and serpentine based on SHMP. Results from artificial mixed ore tests demonstrate that the recovery rate of serpentine decreases from 51.22 % to 37.37 % with the addition of SA, with minimal impact on the recovery rate of pentlandite. To explain the impact of the SA adsorption process on the mineral states, the following tests and analyses were conducted: TOC and QCM-D results indicate that SA mainly adsorbs onto serpentine, forming rigid adsorption at low dosages and flexible adsorption at high dosages. Zeta potential tests reveal changes in the surface potential of the minerals, explaining the transition from electrostatic attraction to electrostatic repulsion between pentlandite and serpentine. FTIR and XPS results show that SA chemically reacts with the Mg and Si sites on the serpentine surface through its -COO- groups. In summary, in the SHMP system, the use of gel adsorption and the chemical interaction of SA to coagulate and depress serpentine reduces its entrainment into the concentrate, achieving efficient separation of pentlandite and serpentine. However, high dosages of SA do not yield satisfactory results.

Separation of sphalerite and dolomite using sodium alginate as an environmentally friendly depressant in a carbonate-hosted Pb-Zn ore system

Magnesium in zinc concentrate causes serious environment problems during hydrometallurgical processes. In the flotation of carbonate-hosted Pb-Zn ore, the separation of dolomite is critical to obtain high-quality zinc concentrate. In this study, fine-grained dolomite was found to be more floatable than coarse-grained dolomite, and it was the main cause of magnesium contamination. Entrainment dominated the flotation of fine-grained dolomite. The environmentally friendly sodium alginate (SA) was successfully used to depress dolomite, and the adsorption mechanism was found to be SA molecules chelating with Ca sites on the surface of the dolomite. The adsorption of SA enhanced dolomite hydrophilicity and increased the particle size due to flocculation, which reduced the entrainment. SA depressed sphalerite during flotation, but the Cu2+ ions enhanced butyl xanthate (BX) adhesion and inhibited the depressive effect of SA. Thus, sphalerite maintained good floatability. Overall, dolomite was selectively depressed by SA during the flotation of sphalerite, and the content of magnesium in the zinc concentrate decreased significantly from 3.65% to 2.37%. This study used SA as a dolomite depressant and obtained a higher quality zinc concentrate when floating a carbonate-hosted Pb-Zn ore, indicating its potential for commercialization and widespread industrial application.

Pilot scale recovery of phosphorus as calcium phosphate from nitrified UASB effluent of a potato processor and subsequent reuse in the wet process for phosphoric acid production

In the frame of the sustainable use of phosphorus, a pilot scale experiment ran for more than one year on the effluent of an upstream anaerobic sludge blanket reactor (UASB) of a potato processor to recover phosphorus as calcium phosphate. Calcium phosphate may be mixed with phosphorous ore and as such used in phosphoric acid production. The effluent was first nitrified and - at neutral pH - adding calcium ions from calcium chloride in a ratio of about 4 or 8 relatives to phosphate-P, resulted in 80 % respectively 90 % phosphorous recovery as calcium phosphate. In the P-reactor a brown colour developed, a colour that remained in the precipitates. After ultrafiltration of the nitrified UASB effluent the recovered precipitates still contained organic material. The phosphorous content of the recovered precipitates expressed as P2O5, was 35–40 m%; the precipitates also contained 4–8 m% calcium carbonate. Except for the criteria for organic material (best 1.67 m% TOC vs 0.40 m%)) and magnesium (0.56 m% as MgO vs 0.11 m%), the precipitates fulfilled all the criteria for phosphorous ore. In a two-step calcination process milled colored precipitate was converted over a light grey (600 °C) to a pure white product (900 C°). This calcination enhanced the crystallinity of the precipitates. A mixture of non-calcinated precipitates (total 30 kg) was used for phosphoric acid production. Both the acid and the isolated calcium sulphate were colored but fulfilled most other chemical criteria. Not the magnesium contamination but either the contamination with organic material appeared to be a problem.

Caracterização química do solo em uma área de recuperação de um depósito de metalurgia de zinco

Ore processing generates a large amount of sterile and waste from purification and concentration processes. This material, in contact with the environment, can cause major environmental impacts. CMM-Votorantim at Três Marias benefits silicate and sulphide Zn ores. The tailings from one stage of the process are deposited in an area called PH9 on the banks of the São Francisco River and subsequently removed and placed in a waterproofed settling basin. The area of the old deposit presented problems in the process of environmental recovery and, therefore, it became opportune to investigate chemically the level of contamination there. The area has 14.4 ha and is located in the municipality of Três Marias / MG with a slope towards the bed of the São Francisco River. The soil samples were collected in two cross profiles, one North - South and the other East - West, totaling 29 georeferenced points with a distance of 20 m. A soil sample was collected at each point. After preparation at the Soil Laboratory of Unimontes, Campus Janaúba - MG, the samples were analyzed in the ICP OES laboratory of the NGqA of the CPMTC of UFMG - Campus Belo Horizonte. Total and available concentrations of calcium, magnesium, aluminum, iron, manganese, copper, zinc and organic matter, together with pH were determined. For the graphical representation, we opted for a grouping the results in pH ranges versus concentrations. The results show that the area has magnesium contamination, thus causing severe structural degradation of the soil. The concentrations of the other elements in the PH9 area are within the limits allowed for land use in agricultural activity, but approaching the upper limit allowed.

Synthesis, characterization and properties of an anionic polymer for water-based drilling fluid as an anti-high temperature and anti-salt contamination fluid loss control additive

An anionic polymer P (ANAN) of acrylamide, N-vinyl-2-pyrrolidone and 2-acrylamide-2-methylpropanesulfonic acid was synthesized through free radical polymerization and initiated by 2,2′-Azobis (2-methylpropionamide) dihydrochloride as an anti-high temperature and anti-calcium and magnesium contamination fluid loss control additive for water-based drilling fluid. The P (ANAN) was characterized by 13C-NMR and 1H-NMR, FTIR, elemental analysis and GPC analysis. The fluid loss tests were carried on different WBDFs. The results showed that this polymer can resist 4.5 × 105 ppm of Cl−1, 4 × 105 ppm of Ca2+ contamination at low pH environment caused by acid gas invasion in drilling fluid at 180 °C. The fluid loss control mechanisms of P (ANAN) were investigated by Zeta potential analysis, particle size distribution analysis and mud cake quality analysis. The thermal stability was investigated by TGA analysis. The results illustrate that the P (ANAN) exhibits a stronger interaction with clays and higher-temperature resistance, and it can improve the colloidal dispersion property obviously for drilling fluid under salts, calcium and magnesium contamination and even under circumstances of acid gas invasion conditions. Due to its superior fluid loss control properties, the P (ANAN) can be a promising polymer for water-based drilling fluid in deep and ultra-deep well drilling applications.

Magnesium Removal from Concentrated Nickel Solution by Solvent Extraction Using Cyanex 272

The refinery of mixed hydroxide precipitate (MHP) from nickel laterite processing by acidic re-leaching will generate a concentrated nickel solution containing some magnesium difficult to remove. Fluorite precipitation method is often used for nickel purification from magnesium contamination, causing serious risk of environmental pollution. Solvent extraction technology has obvious advantages in metal separation and purification which has been widely used in nickel cobalt industries. Magnesium separation from nickel in a synthetic re-leach solution by solvent extraction using Cyanex 272 (bis (2, 4, 4-trimethylpentyl) phosphinic acid)) and its analogue of P 507 (2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester) was studied. It was found that the separation factor of magnesium over nickel reached higher than 200 at pH 5.5, which is much better than that of P507 with the maximum separation factor of 88 at pH 5.0. The conditions including equilibrium pH, organic concentration and A/O ratio for metal extraction and separation of Mg and Ca from nickel with Cyanex 272 in a concentrated synthetic nickel solution were optimized. A five-stage counter-current batch continuous test was carried out with Cyanex 272 under optimized conditions. More than 99% of the magnesium was removed from the synthetic solution containing 3.4 g/L Mg and 106 g/L Ni using 0.5 M Cyanex 272, leaving only 38 mg/L Mg in the purified nickel solution, which is suitable for the electrowinning.

Magnesium Contamination in Soil at a Magnesite Mining Area of Jelšava-Lubeník (Slovakia)

Magnesium contamination in soil at a magnesite mining area of Jelšava-Lubeník (Slovakia) and their effect to the soil characteristics were determined. Soil samples were collected in the area Jelšava – Lubeník with specific alkaline pollutants, it is one of the most devastated regions of Slovakia and with the alarming degree of environmental damage. Magnesite air pollutants are a mixture of MgO and MgCO3 due to which a soil reaction can move above pH 8. Production of clink accompanies the enormous emissions of dust particles of MgO into the air and the leakage of gaseous compounds, mainly SO2 and NOx. The total content of heavy metals in soils (Pb, Zn, Cr, Mn, Mg) were determined by atomic absorption spectrometry and X-ray fluorescence spectrometry. Soil reaction was determined in solution of 0.01 M CaCl2. The research showed that the investigated sites are mostly strongly alkaline. Based on the obtained results, it can be stated that the contents of Pb, Zn is below the level of toxicity but for Cr, Mn and Mg, it does not apply. Their significant exceedance points contamination in which we can take into account the harmfulness and toxicity.

Magnesium Contamination in Soil at a Magnesite Mining Region of Liaoning Province, China.

Magnesite is the world's most important source material for magnesia refractory production, and Haicheng City in Liaoning Province, China has been called "the magnesium capital of the world." However, magnesite mining in these areas has caused serious environmental problems. Field investigations have shown that the soil profile of many sites in the mining region are contaminated by magnesium, and the magnesium-enriched crusts that have formed on the soil surface have affected ecologically important soil functions, particularly reduced water penetration rate. Laboratory experiment revealed that anionic polyacrylamide and calcium dihydrogen phosphate can be used to improve soil condition, and have positive effects on soil function. The findings of this study are of significance in the magnetite mining areas, providing clear options for the remediation of soils that should be carried out immediately.

Comparative Study of Blood Collection Tubes and Thromboplastin Reagents for Correction of INR Discrepancies

International normalized ratio (INR) discrepancies were noted between clinical laboratories using various prothrombin time (PT) systems. We studied the influence of different commercial blood collection tubes and different PT systems on INR measurements. INRs of fresh patient samples were determined by 3 laboratories, each using different PT systems. In the first part of the study, samples were drawn with Vacutainer tubes and in the second part with Monovette tubes. In the first part of the study, the maximum bias for all patients amounted to 0.46 INR (14%), and in the second part, to 0.14 INR (4.9%). The maximum bias for all patients could be reduced further by local system calibration using frozen pooled plasma specimens. The sodium citrate solutions in the blood collection tubes were contaminated with magnesium ions (approximately 2.7 mmol/L and 0.3 mmol/L in the Vacutainer and Monovette, respectively). INR discrepancies could be explained largely by this influence of blood collection tubes. The maximum allowable magnesium contamination in sodium citrate anticoagulant solutions should be less than 1 mmol/L.

The use of in situ powder X-ray diffraction in the investigation of dolomite as a potential reversible high-temperature CO2 sorbent

We report the use of gas sorption experiments and in situ powder X-ray diffraction to study the use of dolomite (MgCa(CO3)2) as a potential reversible high-temperature CO2 sorbent. When dolomite is treated in inert atmosphere at 900 degrees C it decomposes into separate CaO and MgO rich phases and dolomite is never reformed pon CO2 sorption. Gas sorption studies show that the calcined dolomite can go through several cycles of CO2 sorption/desorption in a reversible manner, however, the sorption capacity diminishes with each cycle. Only calcium seems to be involved in the CO2 sorption, while MgO acts as a carrier for the calcium phase. Some evidence of magnesium contamination of the calcium phase was found. BET and SEM measurements were carried out to find differences in the surface area/particle morphology that may explain similarities in the sorption capacities of dolomite and calcite (CaCO3).

Effect of magnesium contamination in evacuated blood collection tubes on the prothrombin time test and ISI calibration using recombinant human thromboplastin and different types of coagulometer

The purpose of the present study was to assess the effect of two types of evacuated blood collection tube on the prothrombin time and international sensitivity index (ISI) of Recombiplastin, a recombinant human thromboplastin. Vacutainer tubes were compared with Venoject II tubes. Magnesium contamination was detected in the sodium citrate solutions contained in the Vacutainer tubes with concentrations ranging from 1.1 to 1.5 mmol/l. In contrast, magnesium ions could not be detected in the Venoject II tubes. The prothrombin ratio was decreased by contamination with magnesium ions and, hence, the ISI was increased. The magnitude of the effect of magnesium contamination on the ISI was influenced by the type of coagulometer and increased in the order: ACL Advance (3%), ACL-300 (4%), Electra-1000 (6%). The ISI bias is transmitted to the international normalized ratio (INR). In the case of the Electra-1000, the INR bias would be approximately 6% at INR 3.0 if the two types of blood collection tubes would be used without distinction. In a secondary study, the effect of magnesium contamination on the prothrombin time was assessed with the current World Health Organization international reference preparation for recombinant human thromboplastin (rTF/95). Magnesium chloride added to patients' blood (0.2 mmol/l) induced 2.3% reduction of the INR determined with rTF/95 and the manual technique. Conclusion The magnitude of the influence of blood collection tubes contaminated with magnesium on ISI and INR determined with recombinant human thromboplastin depends on the coagulometer.

Prothrombin Time Ratio Is Reduced by Magnesium Contamination in Evacuated Blood Collection Tubes

Magnesium ions were detected in sodium citrate solutions in several lots of evacuated blood collection tubes. The mean concentrations ranged between 1.3 and 1.6 mmol/L. Magnesium was also present in the rubber stoppers of the blood collection tubes and could be leached into the citrate solution. It was shown that magnesium added to citrated plasma shortened the prothrombin time of both coumarin and normal plasma. The effect of magnesium was relatively greater on coumarin than on normal plasma resulting in reduced prothrombin time ratio. Shortening of the prothrombin time was also observed when magnesium chloride was added to dialysed plasma, i.e., in the absence of citrate. These results indicate that magnesium contamination can interfere with accurate INR determination in the control of oral anticoagulant therapy.

Sepiolite from Kramat Pulai, Perak

Meerschaum (sepiolite), believed to be the first reported occurrence in Malay­ sia, is studied by chemical, DTA, optical and X-ray methods. It occurs as a white fibrous mineral in the forms of stringers, veins and films along irregular fractures in the marble host rock from an abandoned quarry. Although meerschaum is a high value industrial mineral, used for making smoking pipes and cigarette holders, this occurrence is too small to warrant any serious investigation. However, the quarry operators in the area should be made known ofits possible economic importance for two reasons. Firstly big veins may be profitably exploited. Secondly it is a source of magnesium contamination for high-calcium limestone users. The reported meerschaum is believed to be formed by hydrothermal activity.

Ore texture and magnesium contamination in ores from Pine Point, N.W.T., Canada

Strict magnesium limits on zinc concentrates pose problems in processing Mississippi Valley type ores where dolomite is the host rock. Mill feed and zinc concentrates from Pine Point Mines Ltd. (N.W.T., Canada) were examined during a period of high magnesium contamination. The feed revealed three zinc-bearing textures: colloform, blocky and disseminated. The first two were related to simple locked particles observed in the concentrate, i.e. locked particles with one approximately planar dolomite/sphalerite boundary. Magnesium contamination contributed by simple locked particles decreased with size, approaching zero at about 37 μm. The third texture was related to complex locked particles in the concentrate, i.e. particles showing fine (−25 μ) associations. These particles contributed a size-independent magnesium level in the concentrate. In the fine size classes (−53 μm) of the concentrate magnesium levels were higher than accounted for by locking. The excess was attributed to entrainment. For the concentrate analyzed is it estimated that overall magnesium contamination was contributed 40% by simple locking, 20% by complex locking and 40% by entrainment.