Certified reference material for iron or sulphur analysis

Abstract

The invention relates to a certified reference material used for iron or sulphur ore analysis and / or quality control. The reference material in question is produced from magnetite (Fe3O4) concentrate obtained from run-of-mine ore concentrate.

Description

[0001] DESCRIPTION

[0002] CERTIFIED REFERENCE MATERIAL FOR IRON OR SULPHUR ANALYSIS

[0003] Technical Field

[0004] The invention relates to a certified reference material used for iron or sulphur ore analysis and / or quality control. Said reference material is produced from magnetite (FeaC ) concentrate.

[0005] The State of the Art

[0006] Ores are deposits of one or more valuable minerals located in the Earth's crust, and metals such as copper, gold and iron, which are very important for industry and commerce, are considered the most valuable ore deposits. Before said minerals are used, they are subjected to ore analysis to understand whether the ore obtained is processable and productive. This analysis not only enables the determination of ore properties, but also proves both the safety of the raw material and the healthiness of the finished product. During these analyses, pure or matrix materials used for calibration, method validation, metrological traceability, and quality control studies (sufficiency testing, quality control cards) are defined as reference materials

[0001] . Reference materials are used to obtain the most accurate results about the quality and reliability of measurement results commonly obtained in analytical chemistry. In order for the reference material to be a certified reference material (CRM), its homogeneity and stability in accordance with its intended use must be proven, and metrological traceability must be provided for the values and uncertainties to be assigned using validated methods in the characterisation of the material [2], For this reason, reference material characterised by a metrologically valid procedure for one or more specified properties, together with a reference material certificate providing a declaration of metrological traceability and the value of the specified property, its associated uncertainty, is often preferred, and while reference materials are not expected to have a certificate, certified reference materials must have both the certificate and the certificate value. Although there are different certified reference materials for ores in the state of the art, the mineralogical properties and matrix structures of CRMs obtained from different geographies may differ. This difference may cause interference during analysis and therefore incorrect analysis results. In addition, difficulties in supply also extend the duration of analyses.

[0007] In a study conducted by Turan et al. [3], which is in the state of the art, the determination of total iron (Fe) amount, method validation and estimation of measurement uncertainty in the reference material production process for iron ore analyses are explained. The reference material described in the aforementioned study contains iron and can be used in iron ore analyses, but the use of said material in sulphur analyses is not included.

[0008] As a result, due to the negativities described above and the inadequacy of existing solutions on the subject, it has become necessary to make a development in the relevant technical field.

[0009] Brief Description and Aims of the Invention

[0010] In the invention, a certified reference material used for iron or sulphur ore analysis and / or quality control is explained. Said reference material is produced from magnetite (FeaC ) concentrate.

[0011] The aim of the invention is to provide a certified reference material that enables iron or sulphur ore analysis and / or quality control. In addition to the presence of FeaC (magnetite) in the structure of the material that is the subject of the invention, there is also FeS2 (pyrite). The total iron parameter is provided by the determination of all iron species in the structure, and the total sulphur is provided by the determination of the sulphur in the FeS2 structure.

[0012] Detailed Description of the Invention

[0013] The invention relates to a certified reference material used for iron or sulphur ore analysis and / or quality control. The reference material in question is produced from magnetite (FesC ) concentrate obtained from run-of-mine ore concentrate and comprises 65.71 % iron (Fe), 0.03% copper (Cu), 0.09% manganese (Mn), 0.26% carbon (C), 0.48% aluminum oxide (AI2O3), 0.68% calcium oxide (CaO), 0.29% magnesium oxide (MgO), 0.07% sodium oxide (Na2O), 0.08% potassium oxide (K2O), 0.06% titanium oxide (TiC ) and 0.68% sulphur (S).

[0014] The preparation method of the certified reference material that is the subject of the invention comprises the process steps of: i. grinding concentrated magnetite ore into 1800 g samples in a rod mill, ii. sieving the ground ore through a circular motion vibrating sieve with 0.106 mm holes, iii. grinding the ground ore remaining on the sieve in a rod mill, iv. sieving the ore, which is ground for the second time in the rod mill, through a circular vibrating sieve with 0.106 mm holes, v. combining ground ores sieved through circular motion vibrating sieve, vi. dividing the combined ores into 8 equal parts by weight with a vibrating feeder and bottle type divider, vii. obtaining 4 ore groups of 12 kg each by combining the ores divided into 8 equal parts in a non-consecutive manner, viii. obtaining 32 identical ore samples of 1 .5 kg each by dividing each of the 4 ore groups into 8 equal parts by weight, ix. obtaining 16 ore samples by combining the ore samples belonging to each ore group, divided into 8 equal parts by weight, in a non-consecutive manner within their own ore groups, x. obtaining 128 identical ore samples by weight by dividing each of 16 ore samples into 8 equal parts by weight, xi. obtaining 256 pieces of 375 g samples by combining 128 identical ore samples in a non-consecutive manner, xii. obtaining 512 samples of 80 g by dividing each of the 256 samples into 8 equal parts by weight and combining the divided ore samples within their own ore groups in a non-consecutive manner, and xiii. bottling the obtained samples.

[0015] Since it is thought that the certified reference material that is the subject of the invention is released below 80 microns, concentrated magnetite ore weighing approximately 48 kg was ground at 83 rpm at full charge by adding samples of approximately 1800 g each time with a laboratory type rod mill, and the resulting product was sieved through a circular vibrating sieve with a 0.106 mm sieve and the oversize was fed back to the rod mill. The material, which was oversize and fed back to the mill, was processed at 83 rpm and sieved again through a 0.106 mm sieve. After the sieving and grinding processes of the sample, grain size analysis was performed on a laser grain size analyser. It was determined that the d80 grain size was 66.6 microns. The main ore sample was loaded into the vibrating feeder and the bottle-type sample divider was numbered from 1 to 8. After the samples were divided into 8 pieces, samples 1 -3, 2-4, 5-7 and 6-8 were combined to form equal pieces of approximately 12 kg with the codes A - B - C - D. The obtained A-B-C-D samples were loaded into the bottle divider respectively and divided into 8 equal parts for sample A, and then, samples numbered 1 -3, 2-4, 5-7 and 6-8 were combined to form approximately 3 kg samples numbered A1 - A2 - A3 and A4. The sample coded A1 was divided into 8 pieces again and samples numbered 1 -3, 2-4, 5-7 and 6-8 were combined to obtain approximately 375 g samples coded A1 W - A1 X - A1 Y - and A1Z. Finally, the sample coded A1 W was loaded into the sample feeder and 8 products coded A1 W1 - A1 W2 - A1 W3 - A1 W4 - A1W-5, A1W-6, A1 W7 and A1W8, weighing approximately 80 g, were obtained. By performing the same procedures for each group, a total of 512 pieces of 80 g final product were obtained. These samples are fully representative of the population. The samples obtained were filled into 13.3 cl amber bottles and capped.

[0016] According to ISO Guide 35, unit homogeneity is controlled with the expression 3 / n . For the homogeneity study, 16 samples were randomly taken from 512 samples, 1 sample from each branch. The analysis of the 16 samples to be used was carried out under reproducibility conditions as described in ISO Guide 35 clause 7.5 [4], Additionally, since the repeatability standard deviation of the measurement method is expected to be small, ASTM E 246 [5] and ISO 2597-4 [6] methods were used for total Iron analysis. Similarly, studies were carried out within the framework of the ASTM E1915 [9] standard for the total sulphur parameter. According to ISO Guide 35, measurements should be made in such a way that a trend (deviation) in the measurements can be distinguished from a trend in the sample series. It has been documented that this can be achieved by measuring repetitions of the samples used in the homogeneity study in a random order. For this reason, the experimental sets detailed below were created and analyses were carried out in 3 repetitions. Repetition No. 1 : 1 -3-5-7-9-1 1 -13-15-2-4-6-8-10-12-14-16

[0017] Repetition No. 2: 16-15-14-13-12-1 1 -10-9-8-7-6-5-4-3-2-1

[0018] Repetition No. 3: 2-4-6-8-10-12-14-16-1 -3-5-7-9-1 1 -13-15

[0019] It was examined whether the data obtained as a result of the analysis studies showed normal distribution. It was observed that 14.93% of the total variation in the total iron parameter data was due to inter-sample variation and 85.07% was due to experimental error. It was concluded that 2.92% of the total variation in the total sulphur parameter data was due to inter-sample variation and 97.08% was due to experimental error (i.e. within-group variation). Residual analysis is performed for the validity of the ANOVA model. The assumption of normal distribution of residuals is checked. According to the Anderson-Darling test, the residuals are normally distributed (p- value=0.545>alpha=0.05). According to the evaluation results, it was seen that the values showed a normal distribution and there was no trend resulting from the filling of randomly selected bottles. Additionally, the data was subjected to outlier testing using Grubb's and Dixon methods. It was concluded that there were no outliers in the study results. Homogeneity assessments using ANOVA are described in clause 7.7 of ISO Guide 35 and annex B3. Accordingly, equations 1 and 2 given below should be used to calculate the standard deviation within the bottle (Swb) and between the bottles (Sbb).

[0020] Equations 1 : sif= -jMSa Equations 2:

[0021] MSa: within-bottle variance mean squares

[0022] MSb: between-bottles variance mean squares

[0023] The values obtained as a result of the calculations are stated in Table 1 .

[0024] Table 1. Data obtained according to equation 1 and equation 2

[0025] The results obtained in the studies were used to calculate the within-bottle standard deviation (Swb) and between-bottles standard deviation (Sbb) values. For the total iron parameter, the within-bottle standard deviation (Swb) was calculated as 0.35%, and for the total sulphur parameter, the within-bottle standard deviation (Swb) was calculated as 0.0080. Likewise, the standard deviation between bottles (Sbb) was calculated as 0.15% for the total iron parameter and 0.0064% for the total sulphur parameter. According to ISO Guide 35, the between-bottles standard deviation (Sbb) value calculated using the one-way variance approach can be considered equal to the uncertainty resulting from homogeneity.

[0026] Stability Studies

[0027] For the short-term stability study, 16 samples used in homogeneity studies were reanalysed. The absence of any change in the samples analysed for 4 weeks showed that the samples were stable.

[0028] Characterisation Study (Assigned value)

[0029] The results obtained from the studies were determined by using the formula below.

[0030] Y : Assigned value

[0031] Yi:Analysis results obtained from studies

[0032] P : Number of studies

[0033] CRM Uncertainty

[0034] The evaluation of the uncertainties arising at each stage of the study was made taking into account ISO IEC Guide 98-3. According to ISO Guide 35, CRM uncertainty is estimated with the following formula.

[0035] Ucrm : 7 Uchar +Ubb +Usts +Ults

[0036] U : uncertainty

[0037] Uchar : Uncertainty arising from characterisation

[0038] Ubb : Uncertainty due to homogeneity

[0039] Usts : Uncertainty arising from long-term stability

[0040] Usts : Uncertainty arising from short-term stability

[0041] The certified reference material that is the subject of the invention can be used in the mining and metallurgy sector; in all chemical laboratories providing iron or sulphur ore analysis and / or quality control services, for purposes such as determining the contents of ore concentrates, quality control studies, calibration, method development, method validation, providing metrological traceability, and measuring the performance of the analyst or device.

[0042] The certified reference material, which is the subject of the invention, was dissolved in acid and analysed for the total iron parameter in the same way as the ores to be analysed. Said material can be analysed by triple acid dissolution, quadruple acid dissolution, dissolution in microwave combustion system and atomic absorption spectrometry (AAS), inductively coupled plasma / optical emission spectroscopy (ICP- OES) after solubilisation by alkaline melting and volumetric analysis, and it can also be used as a solid in the X-Ray Fluorescence (XRF) device. It is suitable as a method to use induction infra-red devices for total sulphur analysis.

[0043] REFERENCES

[0044] [1] Fajgelj , A. (2000, June). Using certified reference materials in Analytical Chemistry

[0045] Researchgate. Retrieved May 4, 2023, from https: / / www.researchqate.net / Dublication / 236881773 Using Certified Referenc e Materials in Analytical Chemistry - Present Status Trends and Needs

[0046] [2] TMMOB Kimya Muhendisleri Odasi, (2013, Mayis). 1. Ulusal Laboratuvar

[0047] Akreditasyonu ve Guvenligi Sempozyumu ve Sergisi, Sdzel bildiri sunumlan [PDF file]. Available from http: / / www.turklab.org / wp- content / uploads / 2013 / ulag1 / U LAG2013sozlusunular.pdf

[0048] [3] Sezai §EN, F. T. (1970, January 1 ). Demir Cevheri analizleri igin Referans malzeme uretim Surecinde Toplam Demir (fe) miktan tayini metot validasyon ve olgum Belirsizliginin Tahmin edilmesi. Dokuz Eylul Universitesi Muhendislik Fakultesi Fen ve Muhendislik Dergisi.

[0049] [4] ISO GUIDE 35: Reference materials — General and statistical principles for certification,” (2016) https: / / www.iso.org / standard / 60281.html Accessed: Feb. 14, 2022

[0050] [5] ASTM E 246-01 : Standard Test Methods for Determination of Iron ores and Related

[0051] Materials by Dichromate Titration (2005) https: / / www.astm.org / e0246-21.html Accessed: Jan. 09, 2022

[0052] [6] ISO / TS 2597-4: Iron ores — Determination of total iron content — Part 4:

[0053] Potentiometric titration method (2019) https: / / www.iso.org / standard / 50478.html Accessed: Jan. 09, 2022

Claims

CLAIMS1. A certified reference material comprising 65.71% iron (Fe), 0.03% copper (Cu), 0.09% manganese (Mn), 0.26% carbon (C), 0.48% aluminum oxide (AI2O3), 0.68% calcium oxide (CaO), 0.29% magnesium oxide (MgO), 0.07% sodium oxide (Na2O), 0.08% potassium oxide (K2O), 0.06% titanium oxide (TiC ) and 0.68% sulphur (S).

2. The production method of the certified reference material according to claim 1 , comprising the process steps of: i. grinding concentrated magnetite ore into 1800 g samples in a rod mill, ii. sieving the ground ore through a circular motion vibrating sieve with0.106 mm holes, iii. grinding the ground ore remaining on the sieve in a rod mill, iv. sieving the ore, which is ground for the second time in the rod mill, through a circular vibrating sieve with 0.106 mm holes, v. combining ground ores sieved through circular motion vibrating sieve, vi. dividing the combined ores into 8 equal parts by weight with a vibrating feeder and bottle type divider, vii. obtaining 4 ore groups of 12 kg each by combining the ores divided into 8 equal parts in a non-consecutive manner, viii. obtaining 32 identical ore samples of 1 .5 kg each by dividing each of the 4 ore groups into 8 equal parts by weight, ix. obtaining 16 ore samples by combining the ore samples belonging to each ore group, divided into 8 equal parts by weight, in a non-consecutive manner within their own ore groups, x. obtaining 128 identical ore samples by weight by dividing each of 16 ore samples into 8 equal parts by weight,xi. obtaining 256 pieces of 375 g samples by combining 128 identical ore samples in a non-consecutive manner, xii. obtaining 512 samples of 80 g by dividing each of the 256 samples into 8 equal parts by weight and combining the divided ore samples within their own ore groups in a non-consecutive manner, and xiii. bottling the obtained samples.

3. The use of the certified reference material according to Claim 1 in the iron or sulphur analyses and / or quality control.

4. A certified reference material produced with a method according to Claim 2.

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